Renix CPS ? No spark

[Ecomike]

Ebay has Google beat to hell and back on this one!

http://motors.shop.ebay.com/__?_from=R40&_trksid=p3841.m39.l1313&_nkw=weather%20pack%20connector&_sacat=&rvr_id=186538265958&MT_ID=335&crlp=2748497271_9887&tt_encode=raw&geo_id=491&keyword=weather+pack+connector&adgroup_id=1082786181

and a tool!

http://cgi.ebay.com/ebaymotors/ws/e...o=CRX&its=S%2BI%2BSS&itu=SI%2BISS%2BUCI&otn=4

Not sure I need the tool, but if I was doing a bunch of them, I would want it. I have similar crimpers around (3 o4 kinds), including Molex, so I may wait and see if I really need the tool. Probably get away with pliers and solder. I ordered 14 weather packs for 87 and 89, roundtoit work/

 

[Ecomike]

OK, now I have a problem! Still not running. New CPS installed. Pulled the HV coil.

The two pins, input voltage I presume, read 2.0 ohms, with a meter impedence of .06, so a net resistance across the HV coil input of 1.4 ohms. I got exactly the same reading on the 2-3 year old coil off of my 87 jeep. So that side looks normal.

I checked from the input side to the HV output and got 4000 ohms. I expected a short, or infinite? So I check the working coil off the 87 Jeep (2-3 year old coil) and it reads 7000 ohms?

What am I missing here?

Can the ignition switch be the problem?

Brand new CPS bad?

??????

 

[Ecomike]

Power off, coil removed from both, the no spark 89 jeep ICM output connectors, reading ohms across the 2 conectors read 13,000 ohms, but the newer ICM (2-3 years old), reads 151,000 ohms across those two pins. That is with both ICMs still connected to the ECU and wiring harness.

Edit: OK, I isolated the ICM, no wires connected, no coil, and I get 20 MegOhms versus 8 MegOhms (reversing the leads, seems their is a diode in the ICM circuits) on the 89 giving me trouble, and infinite resistance, over range, versus 3 MegOhms on the new 87 ICM. No doubt I am seeing some variability from diodes here? But does the data tell me anything usefull? Not sure but I think the meter maxes out at 50 megOhms. Frankly anything over one MegOhm to me is near infinite resistance, so I am not sure that difference means anything useful.

???????

 

[Ecomike]

Well this got REAL INTERESTING this evening.

I checked the CPS on the 87 (running jeep), and it only had .28 volts AC coming out of the CPS on it. A 4 year old CPS, about 50,000 miles. Pretty much the same as the brand new CPS I just installed on the 89!!!

I even pulled out my FET Analog meter, calibrated it and used it to retest both CPS sensors, and I got a range that started at .20 volts and ran up to .28 to .30 volts max and held .28 volts on both while cranking both, with both meters!!!! I had the ICM disconnected during the tests on both.

So I decided to check the fuel pressure. Had 38 PSIG just switching power on, no cranking. And leak down. Pressure held at 38 for 5 minutes. So then I tried to start it again (battery was recharged by then). I had forgotten to reconnect the 3 vacuum lines at the manifold that I disconnected to make room for the fuel hose from the gauge to the fuel rail. So I got thinking maybe the TPS was screwed up, before I realized the vacuum hoses were the issue.

I had 29 PSIG minimum on deceleration, 39.5 with no vacuum to the fuel regulator. And steady 39 PSIG with no vacuum at 4000 rpm, and while running hard from 1000 to 4000 rpm, back and forth a solid steady 39 PSIG. I had a fuel pump electrical issue weeks ago, that was solved by cleaning the connections at the fuel pump.

So I shut it down and tested the TPS. I had .71 volts at idle, engine off, power on. So I reset the TPS. Got it to .815 V at idle. Stress tested and cycle tested it about 20 times. TPS seems to be OK.

Not long ago we were fighting with a bad IAC, and bad New IAC....and at one point I had bent the idle stop ear a tiny bit to compensate for high/low idles, and had gotten use to do that recently. Only I forgot that it also changes the idle minimum low voltage to the ECU, which confuses the ECU over time, as it stores the last average min voltage of the ECU in some kind of history data file. So I started and stopped the jeep about 8 times tonight to clear out the old data as much as possible.

It never died, and actually started running better, less peak to peak variation in the high to low engine RPM in park, drive, and with various engine loads like AC running. Not sure I am entirely out of the woods yet. I plan to install new spark plugs and wires next. I got rid of most of the idle miss already, probably with the new cap and rotor.

And maybe the new CPS is helping, but I have no where near the .5 volt minimum someone posted earlier here as the absolute minimum needed??????? In fact I have barely .28 volts average while cranking on both working jeeps!!!

I did not test it while running, as that may take a scope, or a higher volatge setting due to the ECU DC volatge across the CPS (which I was not aware of till I found it with a meter earlier this week???????).

Is it possible that the ECU sets up a DC current across the CPS, which sets up a larger magnetic field than the CPS alone, that is then perturbed by the flexplate tooth as it passes close to the CPS sensor end? If so is that where the larger signal comes from? The .8 volt that others have mentioned? Or do they just force the CPS sensor closer to the flexplate teeth? I find it hard to believe the ECU can read a .28 Volt signal well enough with all the resistance issues going on in a 20 year old wiring system, but I have two of them running right now with just a .28 volt AC signal while cranking?

Some of the other data I collected below on the ICM and HV coils should be useful in the future to others!!!!!!!

Oh, and my CPS wires are NOT soldered!!! LOL.

 

[Ecomike]

More interesting data. The jeep is still running, and running fine, inspite of only .28 AC volts peak on the bare, mounted CPS (The new one). The old one was the 1989 Renix OEM CPS. Had the Renix name on it even!!!! It was down to .180 AC Volts output while isolated from the wiring harness.

So I tested the running jeep new CPS, while the engine was running, back probed the CPS, and it read 1.62 to 1.68 AC volts on the digital multi meter!!!! IIRC the ECU feed to the CPS power on, engine off, is 5 volts DC.

This just gets more and more interesting as I get more data.


Then I tested the one yellow wire, 2 wire connector, single lead connector on the left side of the ICM (2-wire connector (one wire used) "B"--ECU square wave input ignition coil input according to Joe), which is the signal to the ICM for firing the spark (?), and it read 1.2 AC volts, and .8 DC volts on the digital multi meter with the engine running and the new CPS (the new CPS that only gave me .28 volts AC mounted, but disconnected from the ECU harness, while cranking!!!!

Oh, and the 87 (4 year old CPS) and the new CPS read 225 ohms, at 70 F, while the 1989 Old Renix CPS read near 300 ohms.

here is my old CPU data, before replacing the CPS from the older post:

ICM:

3-wire connector:

"A"--12 volts from B Latch relay. I have 12.5 at the battery, and 11.5 V at A

"B"--ground, dipstick tube. .05 ohms

"C"--tach signal. maximum of .180 MV, There but looks VERY weak! NOTE that .180 MV (.180 V) was all I was getting out of the old CPS (or CKP as the manual calls them)

2-wire connector (one wire used):

"B"--ECU square wave input ignition coil input. 4.8 V power on, 5.1 V while cranking, but no signs of wave signal, solid DC it looks like!

 

[McQue]

Hi Mike... not sure what kind of meter you are using but the typical low cost analog meter is only good for measuring true 60 cycle AC voltage. They are built and calibrated to indicate the RMS value of a 60 cycle symmetrically shaped SINE wave that truly goes negative and positive in equal amplitude above and below ground or 0 volt reference.
Trying to read an alternating DC square wave at some unknown frequency with an AC voltmeter will not give you any semblance of an accurate voltage reading, but you might be able to use it as a reference if you have previously charted signal measurements when things are working and use them to compare against when things aren't working and you are troubleshooting a problem. Cheap analog meters that have low impedance input spec will load a signal down, give you incorrect OHM readings, and are really only good for reading straight DC voltages or true 60 HZ AC voltage, and general resistance readings.
So, if you really want to SEE what is going on, you need a scope.

I picked up a used one on Ebay $50.00 plus shipping. It only has 2 channels and is rated at 20mhz but t is more than enough for automotive. You might want to consider looking around for one, the way you like to dig into circuits and such.

 

[Ecomike]

Hi Mike... not sure what kind of meter you are using but the typical low cost analog meter is only good for measuring true 60 cycle AC voltage. They are built and calibrated to indicate the RMS value of a 60 cycle symmetrically shaped SINE wave that truly goes negative and positive in equal amplitude above and below ground or 0 volt reference.
Trying to read an alternating DC square wave at some unknown frequency with an AC voltmeter will not give you any semblance of an accurate voltage reading, but you might be able to use it as a reference if you have previously charted signal measurements when things are working and use them to compare against when things aren't working and you are troubleshooting a problem. Cheap analog meters that have low impedance input spec will load a signal down, give you incorrect OHM readings, and are really only good for reading straight DC voltages or true 60 HZ AC voltage, and general resistance readings.
So, if you really want to SEE what is going on, you need a scope.

I picked up a used one on Ebay $50.00 plus shipping. It only has 2 channels and is rated at 20mhz but t is more than enough for automotive. You might want to consider looking around for one, the way you like to dig into circuits and such.

FET stands for Field Effect Transistor. Mine is a Micronta, circa 1970's, high end of the market back then ($50 in 1976 was lot of money!), the cadilac of meters at the time, high impedance. My digital meter is high impedance also. I got the same readings with both meters, which was very encouraging. Others and it seems at least that one time Jeep was using the AC setting on the meters to read a reference AC voltage signal across the CPS wires while electrically isolated and while cranking the engine. But I am wondering if people over the years have not corrupted the test procedure and therefore the old reference data.

I have four scopes, that I never use, LOL. Too much touble. One is 1950's Heathkit tube job!

I have not done the math, but the number of teeth times cranking RPM , and times the engine idle RPM would give us the frequency. We don't really care about the real number, only the reference numbers using standard high impedance meters for measurment, which is what we are doing for now.

I don't think I want to get sidetracked into a meter / measurement discussion right now, not on this thread. I am more curious as to why people seem to think they need .5 to .8 volts output on the bare CPS, when mine is only showing .28 volts (new CPS, and 6 year old CPS) and is running both jeeps with same output, on an 87 and 89 jeep?

 

[Ecomike]

OK, I am getting desperate here!!!!!!!! HELP!!!

Am I the only one left on with a running Renix jeep?

I need some other Renix Renegades here to check and post their CPS (or CKP) cranking, while disconnected from the harness, and running engine (reconnected to the harness) AC Voltage readings, like I did below.

Back probing the ICM signal wires while running would also be very interesting.

Anyone? What if I say PLEASE!????:laugh:

 

[joe_peters]

Fighting the flu--I will try and get mine checked tomorrow.

1990 4.0 so we should be close.

 

[Ecomike]

I had two hard starts last two trips, warm engine 2 days ago. Did not start it yesterday. Today, after 30 F overnight cold snap, we got back to maybe 50 F today, I tried to start the 89 after dark tonight, so it was maybe 45 F, and no signs of ignition in five tries, all 5 were good 10-12 seconds of cranking each Cranking, cranking speed was fine. I have a new CPS, new plugs, wires and cap on it already, and it was idling much smoother and steadier than it ever has. I had adjusted the TPS last week.

I may now need to adjust the throttle body, now that other things are fixed, and then reset the TPS again. Uncle Bob made several throttle body adjustments in the past on this one. In addition to still needing other's CPS voltage data on working Renix Jeeps, I need a run down on resetting the factor settings on the throttle body, this includes bending the ear stop and adjusting the screw inside the side of the throttle body. I am thinking the throttle body may be too far out of adjustment now with everything else back to specs. My reason for this, is that it idles in park at exactly 1000 rpm now. It sets at 700 rpm in drive. It may be getting too much air bypassing the IAC? Not sure that is enough to keep it from starting?

I will test all the other sensors when I get time and a little warmer weather in day light here, with out rain!

 

[Ecomike]

Well I got around to retesting my 89 Renix that is once again a non starting problem. CPS was just replaced last week, also plugs, wires, cap and rotor, TPS calibrated, and it ran for 5-6 days before the gremlins returnedhasta.

Old CPS was reading 295 Ohms when pulled (now reads 235 ohms?), and was the OEM 1989 sensor (Renix logo on it!, LOL). Old CPS (CKP) was giving me .18 V on the AC meter(s) tests, new CPS (CKP) was and is still giving me .28 V AC while cranking, but now reads 935 to 852 Ohms (repeated test between cranking, before and after, tested it twice, reversed the test leads even, the resistance changed!) on the bare new sensor. Ambient outdoors is about 60 F. I tested the meter, got .5 ohms grounding the leads to each other, and got 67.8 ohms with a 68 ohm calibration, fixed resistor (which previously tested as 68.4 with the same meter a month ago).

Now as if that is not enough to make me scratch my head, I was getting 5 volts DC to CPS from the ECU, power on. Now I get nothing?, and both wiring harness leads from the ECU that connect to the CPS, are reading 5 meg ohms to the jeep ground and that is with power on or off, and while cranking!!!!!

Guess I got lucky as this was the first sensor test of the day to debug the new problem. I checked the MAP sensor and it is has a good ECU ground, pin A and a good 5 volt signal pin C from the ECU with power on, so the ECU is getting power with ignition switch on!!!

It really sucks when you are considered a Renix expert, and Renix has you scratching your head! Time to look at the electrical charts, pin numbers, wiring, ECU, what PITA!

Any ideas people? I am starting to suspect the ignition switch maybe getting funky, as I have noticed a few times that when I stop cranking and the switch spins to run, the engine catches as fires then, but not sure if it can cause this current problem. Unfortunately, it is 100% will not start now problem.

Where is Joe when I need him?

 

[Ecomike]

Just found my hand written note from earlier today, that I forgot. It showed a pin to pin reading of the CPS harness wires loose, of 9.3 K ohms, power off.

So perhaps the CPS circuit in the ECU is isolated from the vehicle ground, that would explain why the two leads read 5 meg ohms versus the vehicle ground, but I thought one of them read grounded to the vehicle ground last week. Guess I need to check the other running Renix to see what is what.

 

[Ecomike]

Lots of new data. The numbers on the non running 89 changed and it ran today, even restarted. It was warm and humid today.

First off the working 87 Wagoneer, that has no start or run problems:
Note: Unless otherwise noted, voltages were at idle!
87 Jeep:
Power off:
CPS connected to harness: 238 ohms
Bare CPS: 244 ohms
CPS harness wires loose pin to pin: 9.29 K ohms

Power on (engine off):
CPS harness wires loose pin to pin: 0.00 V AC, 0.00 V-AC

Power on, Cranking, engine not running:
CPS disconnected from Harness while cranking: .28 V AC

Engine running, CPS connected (back probed):

At first I was getting .44 V AC at idle and 1.0 V AC at 2500 RPM first 5 minutes. Later I noticed that back probing was giving me trouble, and checked the numbers again, Once I got solid contact back probing I got 1.2 V AC at idle and 2.8 V AC at 2500 RPM, but with poor contact back probing I was seeing .44 volts AC. So my good reading once I got good contact was 1.2 to 2.8 V AC on the CPS with running engine. So that is now confirmed!

So the contacts are little iffy on the back probing. Technique seems to be an issue. I need to get some of those wire piecing clips Tiny pin pierces the insulation that make this a lot easier.

ICM connection data 87:

Power on, Engine off:
Left lone yellow wire: 5 V DC
Next yellow wire, left on Conn #2: 12 V DC
Black middle wire: 0.00 V
Green right wire: 0.2 V DC

Power on, Engine running:
Left lone yellow wire: .57 V DC, .96 V AC
Next yellow wire, left on Conn #2: 14 V DC, .131 V AC
Black middle wire: 0.06 V AC, .03 V DC
Green right wire: 14 V DC, wandering AC signal, unstable signal Note the 89 had 5 V AC here!)

-------------------------------------------------------
89 Jeep (the one with nomad gremlins on board!)

Today I got totally different readings!!!!! And it started today!!! And ran!!! And now I can not make it die unless I turn it off the old fashioned way!

Power off:
Bare CPS: 352 ohms (this is a new CPS)
CPS harness wires loose pin to pin: 9.33 K ohms (was 5 meg ohms last time!)

Engine running, CPS connected (back probed):
1.5 V AC at Idle
2.7 V AC at 2500 RPM

TPS voltage at idle:
.85 V

ICM connection data:

Power on, Engine off:
Left lone yellow wire: 5 V DC
Next yellow wire, left on Conn #2: 12 V DC
Black middle wire: 0.00 V
Green right wire: .2 V DC

Power on, Engine running:
Left lone yellow wire: .57 V DC, .96 V AC
Next yellow wire, left on Conn #2: 14 V DC, .13 AC
Black middle wire: 0.3 V DC, .16 V AC
Green right wire: 12.5 V DC, 5 V AC!!!

89 engine RPM was back down about 200 rpm on average versus last 2-3 weeks. Maybe dirty loose weather back connectors, IAC connectors, or who knows what, but Idle is not as stable as it was last week, and is down about 200 rpm net.

 

[cruiser54]

Mike, have you ever removed the ECU, unplugged it, and used a pick to tighten up the individual connectors in the ECU harness so they grab the ECU pins more tightly? Then, flush the connector and pins with a good quality electronics cleaner before plugging it all back in? A good friend and persistent tech did this as a last resort in trying to solve a situation like yours and it fixed it.

 

[Ecomike]

Mike, have you ever removed the ECU, unplugged it, and used a pick to tighten up the individual connectors in the ECU harness so they grab the ECU pins more tightly? Then, flush the connector and pins with a good quality electronics cleaner before plugging it all back in? A good friend and persistent tech did this as a last resort in trying to solve a situation like yours and it fixed it.

No, not on the 89, but yes on the ECU and TCU on my 87. Experience on the 87 tells me it is likely other connections or wiring loom issues that are the problem, as the ECU and TCU connectors seem to be a different, much tighter breed than the under the hood weather packs. I need to look under the dash and make sure there is no spliced stuff there going bad, as the old 89 CPS was soldered under the hood, the weather packs there on the CPS were gone! They may have done some splice soldering under the dash I don't know about that has gone bad on the CPS wires to the ECU.

 

[Ecomike]

So, since I have one, 87, that holds about 750 rpm in park, drive, with and with out loads like AC on, I suspect that is normal? But this 89 has always run about 200 rpm faster in park, than in gear? The idle speeds up a tiny bit, maybe 25 rpm when AC clutch turns on, so that part is OK. Could the 89 idle be programmed differently?

Right now, after the last adjustments I made tonight, 89 idles in park at 975 rpm, till hot, and idles at about 750 in park hot. Drops 200 RPM in gear, D or R, hot or cold. I has been that way since I bought it 3 years ago.

The 87 use to idle all over the place, till I had it fixed (LOL), till I solved all the problems it had!!!!

I can see high idle issues that an ECU and IAC can not compensate for, like vacuum leaks. I could see an O2 sensor lying to the ECU saying I am too rich, cut back on the IAC air feed, and thus undershooting and overriding the 750 RPM idle target. That is why I think my O2 may be involved, but if anything this jeep runs a little lean, it gets incredible gas mileage, which is backwards to my prior statement, and the O2 sensor would not affect starting. Not starting is what started (LOL) this little party.

I am thinking of installing a new B+ latch relay, just in case it is part of the occasional no start restart problem, not resetting the IAC every time, and flooding or starving the A/F mixture at a critical restart time. The relay works most of the time, I watched it work on the meter several times today, but it may be on its last legs?

One consistent item is the starting rpms runs up to 2200 to 2700 RPM first 3-4 seconds, like it has too much fuel already.

Now that I have refreshed all the grounds and sensor contacts (MAT, MAP, TPS and CPS so far) and new plugs, wires and rotor & cap, it purrs like a kitten again. The old idle miss is finally gone so all the work has payed off there.

IIRC, my 87 has the same idle speed in park as it does in D, 750 RPM. The 89 is dropping about 200 to 250 RPM going from park to D. I have no vacuum leaks in either jeep. I am wondering if the O2 sensor on the 89, or something I have forgotten can be causing this?

I ran the 89 today, live TPS voltage about 3 hours, about 12 on off start, stop cycles, with AC, head lights, blower on max, all loads maxed out, and D and R on AW4, and spend hours, cycle testing combinnations trying to make the jeep die. It would not. The idle TPS voltage stayed steady, +/- .05 V DC Max variation from cranking idle to running idle, and only .02 V running as I switched accessories on and off, head lights Max AC..!

Then after cleaning all the sensor grounds and contacts, and engine and body grounds, and a dozen restarts with no problem, I tried starting with head lights on, and it failed to start ( I was trying to see if I could make it now start again).:bawl: Then it failed to start with head lights off second, 3rd, 4th...5th try still no start. So I hooked the V meter up to the CPS to watch AC Volts while cranking and it started right up, never could get it to not start again. I even turned on the Radiator fan and head lights while cranking and it started twice!

Joe_peters say my sh*t is haunted! I think it is electron Pirates!:skull2: loose in the wiring. :eyes:

 

[Ecomike]

OK, I figured out part of the idle issue. The 87 has a slipping transmission, and TC, so there is little to no load on the engine in D lately. I have decided to replace the B+ latch relay next, as it maybe on its last legs.

 

[cruiser54]

Mike, there is a difference in ECUs from 1987 to 1990. That's where they picked up the HP through the Renix years, with more aggressive timing and fuel curves along with some "stabilizing" of the idle. Throttle response was better, especially right after a shift with the automatic. They're interchangeable and all now supercede to the 1990 ECU.

Have you added any grounds to this Jeep or just refreshed the ones you have?

 

[Ecomike]

So if I want to stock up on ECU's I want the 1990?

I replaced the grounds with better ones and added one long ago. I have tested all the engine, body, battery grounds and + connections, they are all great (last night) my worst reading was 16 MV (0.016 V) from the firewall ground connector to the negative post on the battery, with head lights on, e-cooling fan and AC on max and AC fan on high. With those accessories all off it drops to .001 V, 1 MV.

I have one 12 V+ from the battery to the starter solenoid-relay that I need to replace, but it is still OK. It is the one that carries 12-14 to everything but the starter. I plan to test it when I have help for starting voltage drop, versus the battery, but since it started with the E-cooling fan on (manual override) and the head lights on, I don't see how I could have a voltage drop issue there related to starting. And I have had no charging, battery alternators issues for 3 years since I bought it and first repaired everything.

I need to still do a crank test of the ground, and clean the dipstick ECU sensor ground again, but I could find no indications of a TPS ground fault (all though I have a back up, additional ground on it directly to the battery), so while I doubt it is an ECU ground issue at the dipstick, the ECU ground connector is not the same as the starter ground connector, so I do need to verify (clean) that one again. IOW, I guess it is still a potential suspect.

 

[cruiser54]

Yes, stock up on 90 ECUs. Even 89s were better than 87 to 88s.