winterbeater
NAXJA Forum User
- Location
- Royal Oak, Michigan
Wires from PCM to injectors? Or (hopefully not) PCM issues.
-
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Cylinder misfire, vacuum leaks and . . . ?
- Thread starter SuzysJ
- Start date
MJR
NAXJA Forum User
- Location
- Costa Mesa, CA
I don't know if you have checked the following or not but here's a few ideas.
I'd suggest looking at the cam sensor/oil pump drive to see if it's moved at all. You can look at where the hold down clamp is for any signs. Assuming the clamp is tight if you see a mark/shaving/gouge in the aluminum where the clamp sits then it's moved most likely. We did have some problems with the cam sensor/oil pump drives seizing up. Movement can be a early warning sign to failure. The only way I know of to adjust the cam sensor sync is with a factory scan tool. One goes into the "set sync" screen to look at it and set it. Do not rely on the normal sensor screen to tell you it's in sync, you must check it in the "set sync" screen. Set it as close to 0* as possible.
I'd also suggest doing a cylinder leak down test. This will help you determine whether or not you have a mechanical problem. We have also seen problems with the exhaust valves getting pitted around the sealing surface.
I'd suggest looking at the cam sensor/oil pump drive to see if it's moved at all. You can look at where the hold down clamp is for any signs. Assuming the clamp is tight if you see a mark/shaving/gouge in the aluminum where the clamp sits then it's moved most likely. We did have some problems with the cam sensor/oil pump drives seizing up. Movement can be a early warning sign to failure. The only way I know of to adjust the cam sensor sync is with a factory scan tool. One goes into the "set sync" screen to look at it and set it. Do not rely on the normal sensor screen to tell you it's in sync, you must check it in the "set sync" screen. Set it as close to 0* as possible.
I'd also suggest doing a cylinder leak down test. This will help you determine whether or not you have a mechanical problem. We have also seen problems with the exhaust valves getting pitted around the sealing surface.
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
I'm sorry to be so long in thanking you for your advice. I should be getting some $$ freed up in the next month or so to do some long-delayed work, and I very much appreciate this bit of further depth. We'll be keeping the Jeep long enough for me to trace out any and all problems I can find.
I love a smooth-running stock vehicle that age and miles haven't defeated. This ones a baby compared to the last one that was a DD at 33-years.
.
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
Time to go back through this again. 2001 XJ Auto/2WD @ 136k miles
At that time (above) replaced spark plugs, an injector and went to dealer for vacuum/emissions hose harness (to canister). Running and symptoms are similar enough to simply continue thread.
Still have not done more diagnostic as earlier planned. Bigger things got in the way (moved house again; jobs, etc). Still, have replaced power steering pump recently; battery; and drive belt yet earlier.
Had the Auto-Z Actron Scanner on it again yesterday and got the expected cylinder misfire codes plus coolant sensor code (what I expected as still running a bit rough, mpg reduced, and dash coolant gauge showing low).
Am going to replace Champ plugs with the recommended NGK ZFR5N (have gone 14k miles in the past 21-months) and the coolant temp sensor.
Will do compression test. (Leak down test plus any dealer tool use [cam sensor re-set] will have to wait a week or so).
With age/miles am thinking that replacing the coil rail would be good to replace if engine doesn't smooth out some.
The multifunction/turn signal switch is also kaput.
.
At that time (above) replaced spark plugs, an injector and went to dealer for vacuum/emissions hose harness (to canister). Running and symptoms are similar enough to simply continue thread.
Still have not done more diagnostic as earlier planned. Bigger things got in the way (moved house again; jobs, etc). Still, have replaced power steering pump recently; battery; and drive belt yet earlier.
Had the Auto-Z Actron Scanner on it again yesterday and got the expected cylinder misfire codes plus coolant sensor code (what I expected as still running a bit rough, mpg reduced, and dash coolant gauge showing low).
Am going to replace Champ plugs with the recommended NGK ZFR5N (have gone 14k miles in the past 21-months) and the coolant temp sensor.
Will do compression test. (Leak down test plus any dealer tool use [cam sensor re-set] will have to wait a week or so).
With age/miles am thinking that replacing the coil rail would be good to replace if engine doesn't smooth out some.
The multifunction/turn signal switch is also kaput.
.
- Location
- MilkyWay Galaxy
I am reading this thread for the first time. Regarding the comment above, I discovered that OBD-II is programmed to shut off fuel to any cylinder that has too many miss fires, something like 200 miss fires in a certain time period. Then it shuts off fuel to that injector, which leads to even worse engine missing. So testing, requires resetting the PCM!!!! The program code is intended to protect the Cat converters from too much raw fuel.
- Location
- MilkyWay Galaxy
It may not be a lean issue. Crank it up at night and see if the exhaust manifold glows, after resetting the PCM!!!!!
IF it was a lean issue, it would probably over heat the cooling system!!!!
- Location
- MilkyWay Galaxy
"The four bolts holding the fuel rail were removed after disconnecting battery"
Disconnecting the battery may have reset the PCM into relearn mode, and may be why it ran smooth again!!!!! It may not be the new injector that fixed it!!!!
Disconnecting the battery may have reset the PCM into relearn mode, and may be why it ran smooth again!!!!! It may not be the new injector that fixed it!!!!
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
Thanks All (you're posting faster than I can respond).
The past few thousand miles have seen a close to 16-mpg average (corrected) for mixed city; a couple of mpg low. Have several things going on, just not in a position to throw stuff out and replace which I would "normally" do (one reason I keep this: simple, and cheap), but too much other happening past couple of years.
Your suggestion is now on the list as an ECM re-set TSB for misfire in a post farther above was also noted.
Drivers of this vehicle also report occasional no-start (wait, then it will start) so I'm suspecting yet more, as in this post.
Time to be thorough.
The past few thousand miles have seen a close to 16-mpg average (corrected) for mixed city; a couple of mpg low. Have several things going on, just not in a position to throw stuff out and replace which I would "normally" do (one reason I keep this: simple, and cheap), but too much other happening past couple of years.
Your suggestion is now on the list as an ECM re-set TSB for misfire in a post farther above was also noted.
Drivers of this vehicle also report occasional no-start (wait, then it will start) so I'm suspecting yet more, as in this post.
Time to be thorough.
- Location
- MilkyWay Galaxy
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
Disconnecting the battery may have reset the PCM into relearn mode, and may be why it ran smooth again!!!!! It may not be the new injector that fixed it!!!!
Batt has been disconnected numerous times for other reasons. Not saying wrong, but not quite new either.
The 2001 head, casting number 0331 (IIRC) is well known for cracking too!!!
Aware of this. No overheat problems noted, (nor ever any loss of coolant). Vacuum leak repair took care of early post indications of hot running (and shimming hood).
To re-cap, today will be compression test, spark plugs (plus boots) and coolant temp sensor. May try coil rail later this week. Dealer diagnostic tools will wait a bit.
Will start to look at CPS stuff as in older posts above, and in new link just above.
Anything else?
.
Batt has been disconnected numerous times for other reasons. Not saying wrong, but not quite new either.
The 2001 head, casting number 0331 (IIRC) is well known for cracking too!!!
Aware of this. No overheat problems noted, (nor ever any loss of coolant). Vacuum leak repair took care of early post indications of hot running (and shimming hood).
To re-cap, today will be compression test, spark plugs (plus boots) and coolant temp sensor. May try coil rail later this week. Dealer diagnostic tools will wait a bit.
Will start to look at CPS stuff as in older posts above, and in new link just above.
Anything else?
.
Last edited:
- Location
- MilkyWay Galaxy
If you are loosing coolant now as well, it is probably a cracked head. IIRC, Check the passenger side for the casting number, 0331 is the bad one, it was 2001 year XJs.
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
No, no coolant loss. Hoses, clamps, thermostat all replaced when purchased 5/6 years ago. Coolant replaced yet again a couple of years ago. Not ever any loss. I may replace thermostat today to get back to a 195-F unit, have a 185-F unit in there to have covered the great distance son was away when in officer training at that time; a slight loss of temp meant some mpg loss.
- Location
- MilkyWay Galaxy
Is it still running hot? If so do the night time inspection for glowing exhaust. It would indicate a burned valve.
If the #1 injector was truly bad, and if it was stuck open, leaking fuel, it might have made the exh manifold glow red (running rich), causing the excess under hood heat, with out over heating the engine coolant system, and caused the initial miss firing. IF so, then the excess fuel may have washed the cylinder oil off causing excess wear on that cylinder wall/rings. So if compression is now a little low there, it will lead to miss fires, and eventually the PCM will shut down that fuel injector, yet again.
I had that problem with my sons Ford a few years back (also had some loss of valve sealing in the oil seals later but it was not the initial problem, and tiny cracks in the head. I used a combination of Restore in the engine oil and coolant block crack sealer (light duty, the Bars leaks brown pellets in the coolant system).
http://www.restoreusa.com/?gclid=CM30qYLCoqwCFcx-5Qod5Cce1A
It got him another 30,000 miles and a year before we finally had to do a head job for a leaking oil seal on the valve stem, not for the cracked head, low compression. The Restore brought the #1 compression back up from about 80 to 105 Psi. The oil seal on the valve stem got worse and forced to head work, before the sealed cracks and washed walls got to him.
In your case it the compression is a little low on #1 now, I would try Restore till you have time to do the repairs.
If the #1 injector was truly bad, and if it was stuck open, leaking fuel, it might have made the exh manifold glow red (running rich), causing the excess under hood heat, with out over heating the engine coolant system, and caused the initial miss firing. IF so, then the excess fuel may have washed the cylinder oil off causing excess wear on that cylinder wall/rings. So if compression is now a little low there, it will lead to miss fires, and eventually the PCM will shut down that fuel injector, yet again.
I had that problem with my sons Ford a few years back (also had some loss of valve sealing in the oil seals later but it was not the initial problem, and tiny cracks in the head. I used a combination of Restore in the engine oil and coolant block crack sealer (light duty, the Bars leaks brown pellets in the coolant system).
http://www.restoreusa.com/?gclid=CM30qYLCoqwCFcx-5Qod5Cce1A
It got him another 30,000 miles and a year before we finally had to do a head job for a leaking oil seal on the valve stem, not for the cracked head, low compression. The Restore brought the #1 compression back up from about 80 to 105 Psi. The oil seal on the valve stem got worse and forced to head work, before the sealed cracks and washed walls got to him.
In your case it the compression is a little low on #1 now, I would try Restore till you have time to do the repairs.
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
Okay, started on the easy stuff:
Compression Test: (cold motor)
1 - 161#
2 - 161#
3 - 154#
4 - 157#
5 - 157#
6 - 155#
Installation of:
[6] ea; NGK ZF5RN spark plugs
[6] ea; Spark Plug Coil Rail Boots w/inserts
[1] ea; Temperature Switch; Coolant Sensor
Took it for a mild drive (53-mph, highway; 33-miles; 1800 or 2,200-rpm) and, with switching trans from OD to Direct and back, with and without tailwind, saw good mpg on overhead, but dash coolant temp gauge never rose as high as it should. Turned on A/C and headlights, but, short of running in Second (as done several weeks ago) temps did not rise to op temp.
Idle was slightly smoother, no other problems noted, but it's not yet where it should be.
Thermostat will be replaced with factory spec temperature piece next.
.
Compression Test: (cold motor)
1 - 161#
2 - 161#
3 - 154#
4 - 157#
5 - 157#
6 - 155#
Installation of:
[6] ea; NGK ZF5RN spark plugs
[6] ea; Spark Plug Coil Rail Boots w/inserts
[1] ea; Temperature Switch; Coolant Sensor
Took it for a mild drive (53-mph, highway; 33-miles; 1800 or 2,200-rpm) and, with switching trans from OD to Direct and back, with and without tailwind, saw good mpg on overhead, but dash coolant temp gauge never rose as high as it should. Turned on A/C and headlights, but, short of running in Second (as done several weeks ago) temps did not rise to op temp.
Idle was slightly smoother, no other problems noted, but it's not yet where it should be.
Thermostat will be replaced with factory spec temperature piece next.
.
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
Forgot to add:
The Champion R12 stock spec spark plugs looked like what you'd expect for 14k miles: some reddish coloration from additives, no especial gap wear noted, and only a light carboned buildup on shell face. Did see some crud on outer shell where it appears the valve cover gasket is now leaking on 5 & 6.
Coolant looks/smells normal.
Engine oil is darker than usual for this type, miles and use, but no particular fuel smell (my imagination could go either way).
Vacuum gauge diagnosis after coolant temp problem solved (or found); plus will test fuel pressure per links above as well as CPS. Coil rail still a possibility.
Think I'm going to add some MMO to this OCI, as am out of LC-20 at present. May have some valve stick according to exhaust sound after highway drive.
.
The Champion R12 stock spec spark plugs looked like what you'd expect for 14k miles: some reddish coloration from additives, no especial gap wear noted, and only a light carboned buildup on shell face. Did see some crud on outer shell where it appears the valve cover gasket is now leaking on 5 & 6.
Coolant looks/smells normal.
Engine oil is darker than usual for this type, miles and use, but no particular fuel smell (my imagination could go either way).
Vacuum gauge diagnosis after coolant temp problem solved (or found); plus will test fuel pressure per links above as well as CPS. Coil rail still a possibility.
Think I'm going to add some MMO to this OCI, as am out of LC-20 at present. May have some valve stick according to exhaust sound after highway drive.
.
- Location
- MilkyWay Galaxy
I am lucky if I have 120 psi compression on my 87.
278,000 miles.
Sounds like you have most of the problem fixed.
278,000 miles.
Sounds like you have most of the problem fixed.
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
There is a layer of problems to address. Just to be sure that the baseline is good. It runs, but not nearly as well as it should (using the original mpg as control). Then, more service and parts as necessary.
The current thermostat is a #436X-series 180F ROBERTSHAW "Balanced Sleeve" piece (Sold now as Mr. Gasket; see also EVANS COOLING), what used to be the best thermostat, by far. Gotten old, I guess, as it's open all the time. Time to replace.
I used a cold stat to alleviate any potential hot running that my son might experience (forestall radiator problems, etc). But, now that hood is shimmed upwards -- and cowl weatherstripping removed on non-intake side -- engine runs cool. Underhood heat is no longer exaggerated. And, the vehicle is back under my control.
I'll try today to source:
Stant 45359 SuperStat Thermostat - 195 Degrees Fahrenheit
AFAIK what is the best currently available locally.
Once this is in and op-temp back to OEM, then other problems should stand out more clearly.
.
The current thermostat is a #436X-series 180F ROBERTSHAW "Balanced Sleeve" piece (Sold now as Mr. Gasket; see also EVANS COOLING), what used to be the best thermostat, by far. Gotten old, I guess, as it's open all the time. Time to replace.
I used a cold stat to alleviate any potential hot running that my son might experience (forestall radiator problems, etc). But, now that hood is shimmed upwards -- and cowl weatherstripping removed on non-intake side -- engine runs cool. Underhood heat is no longer exaggerated. And, the vehicle is back under my control.
I'll try today to source:
Stant 45359 SuperStat Thermostat - 195 Degrees Fahrenheit
AFAIK what is the best currently available locally.
Once this is in and op-temp back to OEM, then other problems should stand out more clearly.
.
Last edited:
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
Okay, time to update:
Had mini-fuse #17 blow in PDC. Underhood light was toast some time ago and never replaced (thanks, son). Cover came off and switch caught, shorted circuit. No dash or radio.
Drained off a quart of oil and added [1] quart of MMO. Drove XJ up on wheel stands, and just pulled themostat housing loose to clean. Replaced now-ancient ROBERTSHAW 330-195 (I thought it was 180F), as I had bought this piece for a Chevrolet back in the late 1980s. I estimate use at 10-years total and just over 100k miles. Cracked body and stuck open. One worn out thermostat. Used a STANT SUPERSTAT 195F from NAPA. Need to clean system (time and miles). but it looks fine. Just refilled with distilled for now.
Took for a drive and at the 20-mile midpoint, ran up through the gears hard. Could say I felt the engine run a bit looser. A bit smoother. Starting is also a bit smoother. Almost unnoticeable, but good enough to make me believe it is real. With no gauges engine seemed to get all the way up to op temp.
(Confirmed short was underhood light. Dash/radio back to good).
Second order of business was to replace combination turn signal/flasher unit behind left knee bolster below steering wheel on kickpanel. NAPA was good for an EP-27 ($18). Wife had complained of turn signals being in-op at times.
Third was to chase grounds. A thread/title search showed these locations (most of which I had done six years ago when this XJ purchased):
[1] Under/behind air cleaner housing
[2] Firewall to rear of engine valve cover
[3] Three connections to block on passenger side
[4] Removed spare tire and trim, found two just ahead of taillights.
Headlights run off of a custom-built harness installed six years ago, but dash dimmer seems weak. All external lamps replaced six years ago and sockets cleaned and treated with No-Alox. New battery re-treated with No-Alox after terminal cleanup.
While doing the #1 grounds above I didn't think to jumper the computer case to ground and simply unfastened it and laid it aside (no electrical disconnect, just removed mounting fasteners). Computer controlled cars are still new to me, did not own one as my DD until a few years ago. Duh!?
So I now have a record number of codes. XJ runs no differently. Have never had any of these codes before:
OBD-CODES.com
PO130
02 Sensor Circuit Malfunction (Bank I Sensor 1)
Potential Symptoms
Depending if the problem is intermittent or not, there may be no symptoms other than MIL (malfunction indicator lamp) illumination. If the problem is constant, then symptoms may include one or more of the following:
MIL illumination
Engine runs rough, missing or stumbling
Blows black smoke from tail pipe
Engine dies
Poor fuel economy
Causes
Usually the cause of P0130 is a bad oxygen sensor, however this isn't always the case. If your o2 sensors haven't been replaced and they are old, it's a good bet that the sensor is the problem. But, It could be caused by any of the following:
Water or corrosion in the connector
Loose terminals in the connector
Wiring burnt on exhaust components
Open or short in the wiring due to rubbing on engine components
Holes in exhaust allowing unmetered oxygen into exhaust system
Unmetered vacuum leak at the engine
Bad o2 sensor
Bad PCM
Possible Solutions
Using a scan tool, determine if the Bank 1, sensor 1 is switching properly. It should switch rapidly between rich and lean, evenly.
1. If it does, the problem is likely intermittent and you should examine the wiring for any visible damage. Then perform a wiggle test by manipulating the connector and wiring while watching the o2 sensor voltage. If it drops out, fix the appropriate part of the wiring harness where problem resides.
2. If it doesn\'t switch properly, try to determine if the sensor is accurately reading the exhaust or not. Do this by removing the fuel pressure regulator vacuum supply briefly. The o2 sensor reading should go rich, reacting to the extra fuel added. Reinstall regulator supply. Then induce a lean condition by removing a vacuum supply line from the intake manifold. The o2 sensor reading should go lean, reacting to the enleaned exhaust. If the sensor operates properly, then the sensor may be okay and the problem may be holes in the exhaust or an unmetered vacuum leak in the engine (NOTE: Unmetered vacuum leaks at the engine are almost always accompanied by lean codes. Refer to the appropriate articles for diagnosing an unmetered vacuum leak). If the exhaust does have holes in it, it's possible that the o2 sensor may be misreading the exhaust because of the extra oxygen entering the pipe via those holes
3. If none of this is the case and the o2 sensor just isn't switching or acts sluggish, unplug the sensor and make sure there is 5 Volt reference voltage to the sensor. Then check for 12V supply to the o2 sensor's heater circuit. Also check for continuity to ground on the ground circuit. If any of these are missing, or aren't their proper voltage, repair open or short in the appropriate wire. The o2 sensor will not operate properly without proper voltage. If the proper voltages are present, replace the o2 sensor.
PO135
Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
This code refers to the front oxygen sensor on Bank 1. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.
Symptoms
You will likely notice poor fuel economy the illumination of the MIL.
Causes
A code P0135 may mean that one or more of the following has happened:
O2 Heater element resistance is high
Internal short or open in the heater element
O2 heater circuit wiring high resistance
open or short to ground in the wiring harness
Possible Solutions
Repair short or open or high resistance in wiring harness or harness connectors
Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)
PO136
Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
Essentially the same as P0137, a P0136 code refers to the second oxygen sensor on Bank 1. The O2 oxygen sensor produces a voltage between .1 mV and .9 mV. The ECM monitors O2 sensor voltage and determines if exhaust is lean or rich. O2 sensor voltage is high when exhaust is rich and low when exhaust is lean. The ECM monitors this voltage and increases or decreases fuel injector pulsewidth according to engine fuel/air ratio. If the ECM detects low HO2Sensor voltage for an extended period, it will set P0136 Conditions required to set: HO2 sensor voltage is low for longer than 2 minutes (minutes depend on model of vehicle. Could be up to 4 minutes)
Symptoms
There may be no visible symptoms to the driver. Poor fuel mileage, possible misfire, depending on O2 sensor position when sticking.
Causes
A code P0136 may mean that one or more of the following has happened:
Faulty O2 sensor leak in exhaust close to O2 sensor
Short to voltage on O2 signal circuit
Open in circuit resistance caused by corrosion in connector
Possible Solutions
Replace the second oxygen sensor on bank 1
Repair open or short in signal circuit
Clean corrosion from connector
PO155
02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
This code refers to the front oxygen sensor on Bank 2. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0155. See also: P0135 (Bank 1).
Potential Symptoms
You will likely notice poor fuel economy the illumination of the MIL.
Causes
A code P0155 may mean that one or more of the following has happened:
O2 Heater element resistance is high
Internal short or open in the heater element
O2 heater circuit wiring high resistance
open or short to ground in the wiring harness
Possible Solutions
Repair short or open or high resistance in wiring harness or harness connectors
Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)
PO443
Evaporative Emission Control System Purge Control Valve Circuit
The Evaporative Emissions System (EVAP) allows fumes from the gas tank to enter the engine to be burned, rather than vented into the atmosphere as an emission. The purge valve solenoid is supplied switched battery voltage. The ECM controls the valve by operating the ground circuit, opening the purge valve at specific times allowing these gasses to enter the engine. The ECM monitors the ground circuit as well, watching for faults. When the purge solenoid isn't activated, the ECM should see a high voltage on the ground circuit. When the solenoid is activated, the ECM should see the ground voltage pulled low, close to zero. If the ECM doesn't see these expected voltages, or senses an open in the circuit, this code is set.
Potential Symptoms
P0443 trouble code symptoms could be just an malfunction indicator lamp (MIL) illumination. There may be no drivability problems at all. But, it's also possible to have a lean condition or a rough running engine if the purge valve is stuck open. Usually though, these symptoms are accompanied by other EVAP codes. Another symptom may be excessive pressure in the gas tank in the form of a "whooshing" sound when the cap is removed, indicating a purge valve that isn't working at all or stuck closed.
Causes
To cause a P0443, there has to be a problem with the purge control CIRCUIT, not necessarily the valve. Usually they are a unit housing the valve and the solenoid as an assembly. Or it could be comprised of a separate solenoid with vacuum lines to a purge valve. That said, it could be any of the following:
Bad purge solenoid (internal short or open)
Wiring harness chafing or rubbing another component causing short or open on control circuit
Connector worn, broken or shorted due to water intrusion
Driver circuit inside powertrain control module (PCM) is bad
Possible Solutions
1. Using a scan tool, command the purge solenoid to activate. Listen or feel for a clicking coming from the purge solenoid. It should click once, or on some models it may click repeatedly.
2. If it doesn't click with scan tool activation, unplug the connector and examing the solenoid and connector for damage, water, etc. Then check for battery voltage on the feed wire with the key on. If you have battery voltage, then ground the control side manually using a jumper wire and see if the valve clicks. If it does, then you know the solenoid is working properly but there is a problem with the control circuit. If it doesn't click when you manually ground it, replace the purge solenoid.
3. To check for a problem on the control circuit (if the solenoid tests okay and you have voltage to the solenoid) plug the solenoid back in and remove the control circuit (ground) wire from the ECM connector (If you're unsure how to do this, do not attempt). With the ground wire removed from the ECM, turn the key on and then manually ground the Purge valve control wire. The solenoid should click. If it does, then you know there is no problem with the control wire to the solenoid and there is a problem with the ECM purge solenoid driver circuit in the ECM. You'll need a new ECM. However if it doesn't click, then there must be an open in the wiring between the ECM and and the solenoid. You must find it and repair it.
P1491
Rad Fan Control Relay Circuit
PO705
P0705 Transmission Range Sensor Circuit malfunction (PRNDL Input)
I assume that if I can clear these codes they may not come back?
Other than this seem to be back to earlier baseline. Still not running as smoothly as I would like (not as well as our 60th Anniversay '01 XJ which we had from new until 95k when an red light runner totalled it at four years), but now much better than before what with engine running closer to proper op-temp (still just below 200F). With the hood shimmed up and the partial removal of the cowl weather strip greatly increasing the radiatior airflow, I am thinking of finding a hotter thermostat (205F).
Then again, I may get hold of a TUPY rebuild first . . . .
.
Had mini-fuse #17 blow in PDC. Underhood light was toast some time ago and never replaced (thanks, son). Cover came off and switch caught, shorted circuit. No dash or radio.
Drained off a quart of oil and added [1] quart of MMO. Drove XJ up on wheel stands, and just pulled themostat housing loose to clean. Replaced now-ancient ROBERTSHAW 330-195 (I thought it was 180F), as I had bought this piece for a Chevrolet back in the late 1980s. I estimate use at 10-years total and just over 100k miles. Cracked body and stuck open. One worn out thermostat. Used a STANT SUPERSTAT 195F from NAPA. Need to clean system (time and miles). but it looks fine. Just refilled with distilled for now.
Took for a drive and at the 20-mile midpoint, ran up through the gears hard. Could say I felt the engine run a bit looser. A bit smoother. Starting is also a bit smoother. Almost unnoticeable, but good enough to make me believe it is real. With no gauges engine seemed to get all the way up to op temp.
(Confirmed short was underhood light. Dash/radio back to good).
Second order of business was to replace combination turn signal/flasher unit behind left knee bolster below steering wheel on kickpanel. NAPA was good for an EP-27 ($18). Wife had complained of turn signals being in-op at times.
Third was to chase grounds. A thread/title search showed these locations (most of which I had done six years ago when this XJ purchased):
[1] Under/behind air cleaner housing
[2] Firewall to rear of engine valve cover
[3] Three connections to block on passenger side
[4] Removed spare tire and trim, found two just ahead of taillights.
Headlights run off of a custom-built harness installed six years ago, but dash dimmer seems weak. All external lamps replaced six years ago and sockets cleaned and treated with No-Alox. New battery re-treated with No-Alox after terminal cleanup.
While doing the #1 grounds above I didn't think to jumper the computer case to ground and simply unfastened it and laid it aside (no electrical disconnect, just removed mounting fasteners). Computer controlled cars are still new to me, did not own one as my DD until a few years ago. Duh!?
So I now have a record number of codes. XJ runs no differently. Have never had any of these codes before:
OBD-CODES.com
PO130
02 Sensor Circuit Malfunction (Bank I Sensor 1)
Potential Symptoms
Depending if the problem is intermittent or not, there may be no symptoms other than MIL (malfunction indicator lamp) illumination. If the problem is constant, then symptoms may include one or more of the following:
MIL illumination
Engine runs rough, missing or stumbling
Blows black smoke from tail pipe
Engine dies
Poor fuel economy
Causes
Usually the cause of P0130 is a bad oxygen sensor, however this isn't always the case. If your o2 sensors haven't been replaced and they are old, it's a good bet that the sensor is the problem. But, It could be caused by any of the following:
Water or corrosion in the connector
Loose terminals in the connector
Wiring burnt on exhaust components
Open or short in the wiring due to rubbing on engine components
Holes in exhaust allowing unmetered oxygen into exhaust system
Unmetered vacuum leak at the engine
Bad o2 sensor
Bad PCM
Possible Solutions
Using a scan tool, determine if the Bank 1, sensor 1 is switching properly. It should switch rapidly between rich and lean, evenly.
1. If it does, the problem is likely intermittent and you should examine the wiring for any visible damage. Then perform a wiggle test by manipulating the connector and wiring while watching the o2 sensor voltage. If it drops out, fix the appropriate part of the wiring harness where problem resides.
2. If it doesn\'t switch properly, try to determine if the sensor is accurately reading the exhaust or not. Do this by removing the fuel pressure regulator vacuum supply briefly. The o2 sensor reading should go rich, reacting to the extra fuel added. Reinstall regulator supply. Then induce a lean condition by removing a vacuum supply line from the intake manifold. The o2 sensor reading should go lean, reacting to the enleaned exhaust. If the sensor operates properly, then the sensor may be okay and the problem may be holes in the exhaust or an unmetered vacuum leak in the engine (NOTE: Unmetered vacuum leaks at the engine are almost always accompanied by lean codes. Refer to the appropriate articles for diagnosing an unmetered vacuum leak). If the exhaust does have holes in it, it's possible that the o2 sensor may be misreading the exhaust because of the extra oxygen entering the pipe via those holes
3. If none of this is the case and the o2 sensor just isn't switching or acts sluggish, unplug the sensor and make sure there is 5 Volt reference voltage to the sensor. Then check for 12V supply to the o2 sensor's heater circuit. Also check for continuity to ground on the ground circuit. If any of these are missing, or aren't their proper voltage, repair open or short in the appropriate wire. The o2 sensor will not operate properly without proper voltage. If the proper voltages are present, replace the o2 sensor.
PO135
Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
This code refers to the front oxygen sensor on Bank 1. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.
Symptoms
You will likely notice poor fuel economy the illumination of the MIL.
Causes
A code P0135 may mean that one or more of the following has happened:
O2 Heater element resistance is high
Internal short or open in the heater element
O2 heater circuit wiring high resistance
open or short to ground in the wiring harness
Possible Solutions
Repair short or open or high resistance in wiring harness or harness connectors
Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)
PO136
Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
Essentially the same as P0137, a P0136 code refers to the second oxygen sensor on Bank 1. The O2 oxygen sensor produces a voltage between .1 mV and .9 mV. The ECM monitors O2 sensor voltage and determines if exhaust is lean or rich. O2 sensor voltage is high when exhaust is rich and low when exhaust is lean. The ECM monitors this voltage and increases or decreases fuel injector pulsewidth according to engine fuel/air ratio. If the ECM detects low HO2Sensor voltage for an extended period, it will set P0136 Conditions required to set: HO2 sensor voltage is low for longer than 2 minutes (minutes depend on model of vehicle. Could be up to 4 minutes)
Symptoms
There may be no visible symptoms to the driver. Poor fuel mileage, possible misfire, depending on O2 sensor position when sticking.
Causes
A code P0136 may mean that one or more of the following has happened:
Faulty O2 sensor leak in exhaust close to O2 sensor
Short to voltage on O2 signal circuit
Open in circuit resistance caused by corrosion in connector
Possible Solutions
Replace the second oxygen sensor on bank 1
Repair open or short in signal circuit
Clean corrosion from connector
PO155
02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
This code refers to the front oxygen sensor on Bank 2. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0155. See also: P0135 (Bank 1).
Potential Symptoms
You will likely notice poor fuel economy the illumination of the MIL.
Causes
A code P0155 may mean that one or more of the following has happened:
O2 Heater element resistance is high
Internal short or open in the heater element
O2 heater circuit wiring high resistance
open or short to ground in the wiring harness
Possible Solutions
Repair short or open or high resistance in wiring harness or harness connectors
Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)
PO443
Evaporative Emission Control System Purge Control Valve Circuit
The Evaporative Emissions System (EVAP) allows fumes from the gas tank to enter the engine to be burned, rather than vented into the atmosphere as an emission. The purge valve solenoid is supplied switched battery voltage. The ECM controls the valve by operating the ground circuit, opening the purge valve at specific times allowing these gasses to enter the engine. The ECM monitors the ground circuit as well, watching for faults. When the purge solenoid isn't activated, the ECM should see a high voltage on the ground circuit. When the solenoid is activated, the ECM should see the ground voltage pulled low, close to zero. If the ECM doesn't see these expected voltages, or senses an open in the circuit, this code is set.
Potential Symptoms
P0443 trouble code symptoms could be just an malfunction indicator lamp (MIL) illumination. There may be no drivability problems at all. But, it's also possible to have a lean condition or a rough running engine if the purge valve is stuck open. Usually though, these symptoms are accompanied by other EVAP codes. Another symptom may be excessive pressure in the gas tank in the form of a "whooshing" sound when the cap is removed, indicating a purge valve that isn't working at all or stuck closed.
Causes
To cause a P0443, there has to be a problem with the purge control CIRCUIT, not necessarily the valve. Usually they are a unit housing the valve and the solenoid as an assembly. Or it could be comprised of a separate solenoid with vacuum lines to a purge valve. That said, it could be any of the following:
Bad purge solenoid (internal short or open)
Wiring harness chafing or rubbing another component causing short or open on control circuit
Connector worn, broken or shorted due to water intrusion
Driver circuit inside powertrain control module (PCM) is bad
Possible Solutions
1. Using a scan tool, command the purge solenoid to activate. Listen or feel for a clicking coming from the purge solenoid. It should click once, or on some models it may click repeatedly.
2. If it doesn't click with scan tool activation, unplug the connector and examing the solenoid and connector for damage, water, etc. Then check for battery voltage on the feed wire with the key on. If you have battery voltage, then ground the control side manually using a jumper wire and see if the valve clicks. If it does, then you know the solenoid is working properly but there is a problem with the control circuit. If it doesn't click when you manually ground it, replace the purge solenoid.
3. To check for a problem on the control circuit (if the solenoid tests okay and you have voltage to the solenoid) plug the solenoid back in and remove the control circuit (ground) wire from the ECM connector (If you're unsure how to do this, do not attempt). With the ground wire removed from the ECM, turn the key on and then manually ground the Purge valve control wire. The solenoid should click. If it does, then you know there is no problem with the control wire to the solenoid and there is a problem with the ECM purge solenoid driver circuit in the ECM. You'll need a new ECM. However if it doesn't click, then there must be an open in the wiring between the ECM and and the solenoid. You must find it and repair it.
P1491
Rad Fan Control Relay Circuit
PO705
P0705 Transmission Range Sensor Circuit malfunction (PRNDL Input)
I assume that if I can clear these codes they may not come back?
Other than this seem to be back to earlier baseline. Still not running as smoothly as I would like (not as well as our 60th Anniversay '01 XJ which we had from new until 95k when an red light runner totalled it at four years), but now much better than before what with engine running closer to proper op-temp (still just below 200F). With the hood shimmed up and the partial removal of the cowl weather strip greatly increasing the radiatior airflow, I am thinking of finding a hotter thermostat (205F).
Then again, I may get hold of a TUPY rebuild first . . . .
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Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
The PCM isn't grounded through the case. You shouldn't have had a problem unbolting it. I would reset the codes and see if they come back. If they do I would look at the wiring harness to the PCM
SuzysJ
NAXJA Forum User
- Location
- corpus christi, texas
Thanks for the reply. I did remove the grounds from the two attach points on the harness behind the case (clean metal, and re-attach) yesterday prior to that question. In other words, neither case nor harness grounds were always connected to ground for a while. Battery was completely disconnected.
Will look at harness. The high underhood heat problem rears its head (move it, touch it, and you've bought it . . . . )
Today, after trying to clear codes on my own (disconnect battery, turn on ignition and headlights for a 1/2-hr), but with MIL still on, I then went for a 15-mile drive the long way to the parts store. No A/C or other turned on. Trans would not shift into OD, no matter the shifter position. After getting off of highway (a 55-mph trip on a 78-F morning) and idling at stoplight, had a buzzing noise from behind dashboard near A-pillar start. Did not hear elec fan start. Temp gauge did not get to 210F. That "buzzer" quit after a mile. All gauges nominal, MIL light on as before. No pressure build-up behind gas cap.
Once there had these codes: (five codes versus seven)
PO130 o2
PO136 o2
PO443 purge valve
PO705 trans range
P1491 elec fan
(#'s 135 and 155 have fallen away for now)
After code check, picked up noid light and fuel pressure gauge to test that system set. Less than 1/4-mile and MIL was back on.
Have now done a vacuum test. At idle have a steady 18", which lowers to 16" after a minute or so. At high idle have 21". Jeep doesn't like to idle smoothly, get's rougher and engine slows. Loads up a bit. Sound like it will quit, but it "catches" and is kept from dying. I think the vacuum leak problem from earliest post was corrected with parts installed, so am checking that off as done.
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