cherokee headache please help

ok well where do i start. my 93 jeep cherokee just shut off on me today and won't start back up. in thye last few month i have replaced the coil, wires, plugs, waterpump, tps, cps, cap, and rotor. my problem was that when i had the vehicle in neutral it was idling around 500-600 rpm and it will drive fine untilll i come to a stop. when i come to a stop my jeep idles really low and sometime cuts completely out. today i was driving to emissions and it did the same thing, it cut out. but now it won't start back up. i have spark and i have fuel pressure. please someone tell me what i can do, i can't afford to throw any more parts at it.

oh yeah i also replaced the fuel regulator that wasn't working so what do i do now please comeone help me

More than a few things can cause problems like that. One you can check that doesn't really cost anything is the IAC. Take the top off the TB and spray some oil (PB Blaster or whatever) into the IAC opening.
Your motor may be flooded, first try starting it with about 1/8-1/4 pedal and see what happens. Then hold full pedal and let it crank for a long 10 count and try 1/8 pedal again.
Check and see if you are getting good spark.

sorry but what is the IAC

iam also getting a lot of condesation coming out of the tailpipe when i start it

IAC - Idle Air Controller.

This seems to be a common and very plausible answer. You can also remove the IAC and scrub it with some cleaner and a toothbrush.

I would have also shot from the hip at a badly clogged or faulty EGR valve, except I doubt that this would cause your problem of the jeep not starting alltogether, but you haven't lived until you've seen it all.

Check the vaccum line running to the MAP sensor for leaks, cracks or splits. Check the sensor readings of the MAP sensor - consult your Chilton guide and use a multimeter. I can post you the chilton procedure for testing the MAP sensor if you wish.

My last resort to explaining this behaviour is an obscure-ass wire somewhere that cracked and eventually lost continuity in your wiring harness somewhere. This is the ultimate pain in the butt but is also the least likely explanation I can think of.

I have to take a second to frown at your diagnostic process, however. Many of the parts you replaced could have been tested by any monkey owning a multimeter. Hell you could buy a cheap multimeter for 15 bucks at almost any parts store.

No EGR on the 93.

IF you are not having any other problems at all (are you?) then the IAC is probably sticking, or the port it regulates is clogged, both are common sources of idle problems. Search here under "Idle Air Controller" for prior threads that have pictures and blow by blow removal, location and cleaning tips. If the problem persists after cleaning the IAC, then you need to check the wiring to the IAC.

If you are having any other problems, like poor power under load or acceleration, or runs rough all the time at all rpms, etc., we need to hear them! Do you have any intake & exhaust leaks?

8Mud, on the Renix jeeps WOT shuts off the fuel injectors and allows maximum air flow to dry out a flooded engine, so is the 93, OBD-I generation different? I ask regarding your 1/8 to 1/4 pedal comments below.

but how would i go about checking the map sensor

Forget the MAP sensor for now, like I said based on the only problems you posted so far, you need to focus on the IAC. Your problem is not with the MAP sensor, other engine sensors, or even the CPS right now.

You need four things to start the engine, engine rotation, fuel, spark (all of which you have, and since you have spark, you having spark timing as well so the ECU and ECU sensors including the CPS are all OK) so ALL that leaves to be missing is AIR. Try puting the gas peddle to the floor, called WOT, Wide Open Throttle, UIAM, that will cut off the ECU fuel injector power on a 93, just like it does the 87-90 models, cutting off fuel and thus allowing the flooded engine to dry out and start in less than 30 seconds. If that works clean the IAC and the throttle body, and re-oil the IAC. That should solve your problem unless the wiring to the IAC or the IAC itself is bad, which is very unlikely.

The IAC (Idle Air Controller, or Idle Air Stepper Motor as it is sometimes called) is next the TPS, on the throttle body.

what should the voltage to the iac be at with key on

i tried starting it with wot and it tries to start took out the iac and cleaned it and oiled it and the same result. as soon as it let off throttle it bogs down. how do i test voltage at the iac.

ok i got it to run and i took out iac again but is that rod supposed to be screwed all the way in because it was half way out when i took it out. shoul;d i screw this back down or not?

ok again it won't start after cleaning the iac and adjusting it back to where it was suppose to be. it had started once now i have so intermittent problem how do i check the hall effects sensor on the ditributor. if that is not working properly will i still get spark.

Sounds like you are just about there. There is no voltage to the IAC except when the ECU wants to adjust the idle, and then it is only a split second DC pulse to the motor. Jeep made a tool for testing it once, but I have yet to run across one. Most of us clean it, and then if all else fails replace it. The new ones have a warning against moving the pentle (end part) on the shaft beyond certain limits and warnings not to force it. It should only be moved by rotating the pentle. IT should NOT be fully extended when re-installed, other than that I think the ECU cycles it to locate the closed reference position.

By the way, I forget, but did you ever check for OBD-I codes in the computer????

yeah im not getting any codes out of it. and it won't start even with 1/2 1/4 or full throttle or no throttle.

even though i just put a new cps sensor in what is procedure to check this part i bought it from pepboys i would like to double check

cmichaud84 said:

ok again it won't start after cleaning the iac and adjusting it back to where it was suppose to be. it had started once now i have so intermittent problem how do i check the hall effects sensor on the ditributor. if that is not working properly will i still get spark.

Click to expand...

The synch sensor in the distributor tells the ECU when to inject fuel. The CPS tells the ECU when to send the spark.

Bad CPS, no spark,

Bad Synch sensor in distributor, no fuel.

If you have spark, its not the CPS!!!!

Sounds like you need to back up some. You got it to start sort of at WOT earlier. So it sounds like something is coming and going, working one minute then not the next.

Recheck to see that you have a good spark. Take a spare spark plug, install it one of the plug wires, then ground the end to the block. have some one crank the engine and you watch the spark. Gap the test plug at .050, it it will spark at 0.050 you have good volatge and spark. If no spark then the CPS wires to the ECU may be bad.

Then get a small hose, 24" long (apx), 1/4 ID or smaller, place one end near your ear, the other end near the fuel injector(s), one at a time while someone cranks the engine, to listen for a metalic tick as the fuel injector opens and closes. NO TICK, means no fuel which means no signal from the ECU if none of them tick, in which case I would suspect the distributor Synch sensor inside the distributor is bad, or wiring to the distributor.

Not sure, but I would think OBD-I computer would throw a code for a bad CPS???

Recheck and make sure the fuel pump is running and is delivering the proper fuel pressure, all the time! Mainly just make sure there is fuel pressure and make sure the fuel pump is always turning on while the engine is cranked. It should also turn on and a run for a few seconds when the switch is turned to run only, not start. IF not, there may be a bad connection or dying relay in the fuel pump circuit. You mentioned replacing the fuel pressure regulator, what was wrong with it, i.e. how did you test it?

The 93 may have used a ballast resistor on the fuel pump. If so it could be bad, in which case it would start the pump (in bypass mode) for a few seconds, but not run the pump as the engine is cranked.

Sounds like the same problem my 91 is having. I finally got tired of replacing parts so off to the shop it went. As soon as I find out somthing I will post it up.