Dies when warm

I have a 95 Cherokee with the 4.0. I was driving down the highway yesterday and it just died. I ended up trubble shooting and finding no spark. I changed the cps, cap, rotor, plugs, wires, coil, pick-up coil, starter relay, fuel filter, o2 sensor and I cleaned all the grounds. When I got back to the jeep today it started right up and ran fine. I went threw and changed out the parts and took it for a test drive after letting it sit and idle for a bit. I made it about 3/4 of a mile and it started missing and bucking again and when I parked in the driveway it shut down. I dont know where to go from here. The only codes that I am getting are 12, 11 and 55. 11, Im back to the ignition. Do you have and sugestions? Thanks

I was looking at the distributor and found that the shaft had some play in it from side to side. It is more than I have seen before so I think im going to replace it and see if it fixes my problem. Could there be anything else that im missing :dunno: ?

I'd sign up for alldata, check the reference voltage to the cam position sensor or the sync sensor (I think it's now called) in the distributor. The five volt current test is a good indicator of the general health of many other sensors, they share a power supply. If there is a short someplace it may show up as low voltage at the sync sensor.
A MAP sensor will sure enough make it run like crap, stall and die at idle. But form the sound of things, it may be a loose wire and/or a bad connector. You almost have to do a visual inspection of the connectors, plugs and harness. Pins backing out of the connectors, rub throughs on the harness, wires cooking on the manifold and oil leaking into the connectors is fairly common.
The O2 sensor should throw a code if it's really bad. It often appears as a check engine light while driving. The check engine light may go out, them come back on again.
Many of the sensors are bypassed during hard acceleration or near full throttle, this can also be an indicator. Some only work after the engine is warmed up.
I had a bad CPS and replaced it with a new one, which was also right at the edge of the allowable tolerances. It would screw up every time the motor hit a certain temperature. New doesn't necessarily mean good.
I don't envy you trying to figure this one out, it sounds like a hard one.

redneck said:

too much power to the TPS. It is meant to be between .80 and .83 volts from what I have found. I put the volt tester to it and came up with 4.XX volts. driver that I need. :banghead: :explosion :badpc: !!!1 :flamemad:

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NO NO NO ...you mis read that... its meant to be 4.XX volts (mines 4.8)
The after-TPs voltage is meant to be .830 or so, being 80% +/- 3% of the voltage coming into the TPS. Give or take. I just wanted to let you know your voltage is fine there.....
so 4.8 x .830=3.98v out of the TPC at idle.

Theres another very new thread about the very same issue right now..check it out..and try your Crankshaft position sensor

Do you have a vacuum leak? Or maybe EGR problem?

98stocker, I have looked over the vacuum lines and it dose not look like I have a problem. However, when I removed the line on the manifold that runs to the brake booster the idle jumps about 700 rpm and when I cover the hole or replace the line to the manifold it dies.
Wallyman, I replaced the CPS the first time when I had no spark and it brought it back to life. I have spark now but it will hiccup and sputter when I give it throttle. Once it is fully warmed up it will run worse and die. Going to the TPS, it still threw a code after took it off and cleaned the connectors.

If you can hold the throttle plate open (just a crack), just a little and it runs OK, then let the throttle plate go and it dies. It often means the IAC is stuck closed.
Test the MAP with the plug connected, I've used a paper clip to go into the back of the connector to get a good contact. Pins "A" "B" and "C", "A" is ground, check with an ohm meter to see if your ground is OK. "B" is output, with the ignition on and the motor not running it should be 4-5 volts. "B" with the motor running at idle and engine warm should give you 1.5-2.1 volts. "C" is supply (or reference) voltage and should be around 5 volts.
I always use the ground at the plug ("A") and not a chassis ground. If you put two paper clips in the back of the connector, be sure they don't touch each other.
I usually cut a little slot/lengthwise slice with an exacto knife and test straight to the wire core myself and reseal the slice with a dab of silicon. It is sometimes hard to get good conductivity through the back of the connector, especially if you are alone and need three hands.
A bad MAP will make a motor run like crap and you usually can't get the RPM's up very high. It feels like it has no power at all.
A sticky IAC (closed), will not idle and may stall, but will run fine with the throttle open. If the IAC sticks open to any degree you may have a really high idle.
In many of the sensor tests, you will notice the base voltage is right around five volts. If one sensor shorts partially, it can suck down the 5 volt power to other sensors. Even a short in the CPS can cause this.
Test your die electric grease with an ohm meter. I don't use the stuff on sensor connections.
Check the wires to your CPS real good. Make sure you don't have a burn or rub through anyplace.
I usually check the wiring, the grounds and clean the connectors before I even think of sensor tests or replacement.
I use a top quality contact spray and one of those little round nylon bristle tooth brushes for cleaning between your teeth and scrub the pins clean. Put the connector back together again dry.
The MAP test I suggested is for a 96, I'm guessing your 95 is much the same.

Disconnect the battery for half an hour, take it for a test drive. Moderate stop and go, then hit the highway and try for a constant 40-50 MPH after the motor warms up (above 150 or so). When I say constant I don't mean exact, fluctuate it 10-20 MPH.
Under your MAP there is a little rubber elbow, take a look. They don't often mess up, but can be damaged with solvents or oil over time.
Best guess, you have a sensor with a partial short, that is daisy chaining the system into random sensor failures (or periodically out of normal envelope). Maybe a damaged wire, the rear O2 sensor is a likely spot for a burn through and/or short.
You have a pin partially backed out of a connector or poor contact someplace or a harness problem. I had a fatigued wire for the CPS, that was under the insulation. It had been wiggling around for a decade and finally wore all the way through the copper, but didn't affect the plastic covering. Gave em fits trying to find it.
Possible you have already fixed the problem and the computer is trying to operate off of old input info, hasn't been run long enough to reprogram.
A vacuum test could tell you if you have a mechanical problem and or the timing is off. It's sometimes hard to tell the difference between a fuel problem (faulty sensor or fuel system), a timing problem from a faulty sensor input or even a compression problem.
A faulty MAP will often make it run way rich, even after it is at operating temperature. A faulty O2 sensor will often make it run lean, but is only really apparent after it is at operating temperature. A faulty TPS can affect the timing, making it pop during acceleration or have flat spots.

I took the throttle body off yesterday and cleaned it. While I was at it I changed the throttle position sensor, the MAP sensor and the idle air control valve. I put it all back together and I still have the same problem. It starts and jumps to 1700 rpm and then comes down to idle. Once it gets going it has a slight miss at idle and as soon as you give it any throttle it misses like crazy. I took it around the block and it would hesitate off idle and then ping and miss after that. I figured it sounded like timing and since I put a new distributor in I decided to mess with that first. I brought the motor to top dead center so i thought. I put the mark on the harmonic balancer on the 0 degree mark then lined the rotor up with where plug one is on the cap. I went to start it and absolutely nothing happened. That concerns me greatly. I believe that that’s how you set up the distributor. I ended up just messing around with the distributor and the jeep finally fired again when I put the motor TBC the way I believe you do and then lined the rotor up with the number 2 cylinder and it fired right up. Again, it was running the exact same way. I do not know what to look for next or what to do. I have about $300 invested into the Cherokee now and I still can not drive it not to mention the money to tow it back to my house from up state. I need the jeep this week, it’s my daily driver. I am down to $60 and a non drivable jeep. Here is the final list of what I have put into it; plugs, wires, cap, rotor, pick-up coil, distributor, coil, CPS, MAP sensor, TPS, IAC, oxygen sensor, starter relay, fuel pump relay, fuel filter and a cleaned throttle body. It is no longer throwing codes but still running like crap. Where do i go from here? I am at a total loss. I really need any and all help I can get.
Thanks

I think your real problem may be the intake manifold air temperature sensor. It can be tested with a multi meter. Also it sounds like you do not have the distributor lined up properly. I will back in about 90 minutes and ad more here. Gotta run right now to the store. Meanwhile seach here for the real instructions in a prior thread for setting the distributor properly. It should end up with the rotor pointing at about 5 O'clock ( but I need to check that on your year, 95 model first) at the number one plg at TDC as I recall.

Also, send me PM with your email .

What should the volts be on the Air Charge Temperature Sensor? Dose it effect the motor enough not to run?

I'm back. You can test the map sensor (which rarely goes bad), the Intake air temperature sensor, and the coolant temperature sensor by disconecting them and testing the resistance at various temepratures to se if they look right.

I started a thread last year that has a lot if good info in it at:

http://www.naxja.org/forum/showthread.php?t=899397&highlight=idle+speed+wanders

http://www.naxja.org/forum/showthread.php?t=905849&highlight=idle+speed+wanders

I would stop buying parts and start runing Multi meter tests to track down the real problem. Check the ohms resistance (jeep power off) between the battery negative post and the engine (valve cover or engine block) and scratch a clean spot on the engine or valve cover to get a good conact. It should read less than one ohm, if not you still have a ground wire conection problem somewhere. Do the same between the engine and firewall and the firewall and the battery negative post. All should about or less than 1 ohm.

Check the resistance at various temepratures of the two temperature sensors, one in the thermostat housing and the other in the intake manifold.

Try disconecting the TPS and start the car. Let me know if runs OK that way. Do not press the throttle with the TPS disconnected.

Also post some details regarding your experience.

Does it run after start up if your hold the throttle open some or does it die anyway??? That answer will help us pick between the IAC and the ballast resistor. If the ballast resistor goes bad, the engine will start and then die. If the IAC is bad (hanging up) in the closed position it will idle too slow and die unless you hold the throttle open wider than the idle stop does. IAC can sometimes be cleaned and oiled and start working OK again.

Also read over the pdf I sent you about the relearn procedure and problems with idles and poor performance during the computer relaern procedure, which could also be part of your problem since you have changed so many parts and barely run it since then. I would disconnect the battery for 5 minutes, reconnect it to clear the memory of all the old bad sensor data it has and is still using!

Get back with us with on any results you get as it occures.

redneck said:

What should the volts be on the Air Charge Temperature Sensor? Dose it effect the motor enough not to run?

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Disconnect the sensor, set the meter to ohm lowest scale, check the resistance between the two sensor wires. Use the table in the pdf I sent you, or reference the data in the threads I just posted below. At 70 F should have about 3,400 ohms, 160 F it should be 450 ohms. You will need a temperature sensor to verify the actual tempuratures. 100F is 1,600 ohms, and 40 F is 7,500 ohms. Colant temperature should have the values at the same temperatures.

Recheck those grounds next also, I spent two years and a gizzilion dollars on inneeded parts before I finally admited how sensitive these engine computers are to an 18 ohm ground path that should be one ohm or less! Also dirty, loose conectors on the wiring harness can add to the resitance ground path problem sending bad data to the engine computer thus causing high and low idle problems that come and go, seemingly randomly as conectors heat and cool and the contacts resitance increases and decreases.

Well I also think you may have the new distrubutor installed with the timing off by one gear tooth on the distributor / camshaft gear tooth.

I was trying to find an easy pictoral instruction to post a link for you but I have not found one. There are some links with text versions of how to fiddle with the oil pump / gear tooth, rotor pre-position line up .....to get it lined up while the engine is at TDC, but they all looked a bit confusing even to me and I have done it before (fought the battle). As you know by now the shaft rotates while the distributor drops in place so you must pre-back rotate it so that ends up aimed at plug number one on the distributor cap (5 O'clock) once the distributor has dropped all the way in. This is due to the rotation of the curved helical gear on the distributor shaft lining up and meshing with the cam shaft as you drop it into place.

Just go by the final locked (tabbed) position of the rotor cap and the number one plug on it as the place you want the rotor cap to point to when the distributor is finallly locked into place. I know the 1987 Renix is at five O'clock inspite of what the Haynes and ALLDATADIY web sites show. They show it at 6 o'clock for all the 4.0's, so may be it is six o'clock for yours. Anyway, if you just use the tabbed locked in position of the cap and distributor for cylinder/plug wire #1 you can't go wrong.

Anyway, if I am right you need to back it out and reinstall it one tooth forward or reverse of where you have it now to get the basic (non-electronic) timing correct. and others have had it off one tooth, and your some of your performance problems.

I suspect you have the timing off one tooth, and also have an IAC and or MAT (Manifold temperature or Intake Maiflod Temperature sensor ) problem, or some remaining loose connections and or ground problems.

Correction, ALLDATADIY.com shows it as 6 o'clock in a picture, but lists it as 5 o'clock in the text so 5 o'clock is correct for yours and mine (85-96 at least). If your rotor is pointing at the number one plug wire in the cap at 5 o'clock when the engine is at TDC then you do have it installed right!

Ecomike,
Since this all started last weekend I got it to run and then not to die when warm. It came back to life the first time with a new CPS but did not come back running properly. The problem is that instead of it running perfect then missing and dying when warm like before it now has an unsteady idle with hiccups. Once you apply throttle it kicks, sputters and pings all the way threw the rpm. When I disconnected the TPS and started it up it ran worse with a constant shutter. I just replaced the IAC without any change. When I replaced the IAC and TPS I disconnected the battery over night to reset the computer. I have about 20 min of idle time on the motor since then. I unfortunately do not have an ohms meter, I only have a volt meter. I put the volt meter on the Air Charge Temperature Sensor and when I first fired it up it showed 2.6 volts and after 3 min it was putting out 1.9 volts. I hope that helps. It seems to be working. I’m going to put the distributor back in TDC position but I find it disconcerting that I didn’t get anything with it there but when I put TDC to the #2 cylinder it fired right up.

One other long shot, try disconnecting the O2 sensor (as a test only) and restart the engine. If it runs better, check the wiring harness for a short, and check that the O2 sensor is not installed backwards on the connector or that the connectors are not reversed.

I have had both of these happen to me, and one guy had his connector attached to the O2 sensor backwards from the factory. Any one of these makes it run like sh$t.

I am still thinking something is off the distributor timing. can you explain exactly what you did with the @ TDC and #1 TDC.

You do know there is an exhaust and a compression stroke for #1 TDC and that you must have it on the compression stroke of #1 TDC for it to work!