[devzw3jeep]

1994 ZJ 5.2L Intermittent Hesitating and Stalling!

Im going to try to write this with the most information to help solve my issue and also without confusion. Some of you may already know about this problem I have been having but I still can't fix it and I miss my Jeep running good Alright here we go:

Symptoms:
-[Intermittent] Stalls when accelerating (most of my stalling is this way)
-Hickups when accelerating or asking for power (Happens most of the time when I drive)
-Has sometimes hickuped at constant speed around 45mph
-Sometimes takes 1 to 5 minutes to crank up if parked or stalls. (Rarely; usually starts right back up)

Temporary cure: (worked 2 times for about 3 to 5 days)
-first time: -Sprayed TB cleaner in TB and Intake Manifold (3 days cure)
-second time: -Took off and completley cleaned TB and again sprayed TB cleaner in Intake Manifold. Also replaced MAP sensor. (5 days cure; 140 miles)

Things I think could be wrong: (acording to internet and research)
-Bad or Corroded wires or plugs
-PCM (computer)
-Crank Position Sensor
-Cam Sensor
-Intermittent fuel pump? was just replaced in 2009 by last owner (have receipt lol)
-EGR
-Ignition Coil
-Spark plugs, wires, or distributer cap?

Already Replaced:
-IAC valve
-MAP sensor
-Fuel filter
-Used Fuel injector cleaner
-Checked TPS and worked correctly

Things To Consider:
-I still have all Electrical power when it stalls and hesitates
-Just a dead stop or sharp off-on when stalling or hickuping (not sputtering)
-Runs extremely smooth and normal when not acting up
-Has almost never happened at night; only mornings (60 degrees; 4 mile journey) and Daytime (65-99 degrees; usually 4 mile distance but sometimes more) [At night it is also around 60 degrees]
-Is still having the same great gas mileage a jeep gets [lol] (hasnt worsened)

I would replace all of tht but just like everyone else in todays economy, I dont have the money to. Does anyone have any idea what could be troubling me for a month or so now? It seems to be getting mildly worse. Please Help Thanx

 

[JayH]

Does it ever happen in the first two-three minutes of starting it up and driving it away? Or is it always after it has warmed up to normal operating temps?

You didn't say whether you'd checked the fuel pressure with a gauge?

I'd be looking at air/fuel mixture before spark.

 

[devzw3jeep]

It happens once its up to normal running temp. And now tht it got down to 50 degrees here in lancaster california, It hasnt done it to me for 2 days now. I have checked fuel pressure and was running 39psi. I have a question, if the fuel regulater was out, could it cause these issues? because when I tested my regulator (by removing the vaccum and watching the gauge) the pressure remained at 39 the entire time and I heard it is supposed to be around 31? I just dont see how heat could effect the air and fuel mixture?

 

[JayH]

I don't know what fuel pressure is supposed to be, or how it's properly tested, but if it's not within specs then sure bad regulator = bad mixture.

After the engine warms up she enters closed-loop operation where the electronic engine controls (and sensors) work to deliver the exact amount of fuel needed per volume of air and test the results based on the the amount of leftover O2 in the exhaust. Until she warms up, the fuel is delivered at a preset rate.

Given your temporary fixes, I'd be looking more closely at the TPS, and the O2 sensor.

 

[rexxiboy90807]

Have you by any chance disconnected the battery for more than 10mins or so prior to this problem happening? I do not wish to elaborate until you have an answer.
Thanks

 

[devzw3jeep]

I have done the battery disconnect AFTER the problem because I thought that could fix the problem but unfortunately it didn't lol. And just recently I have been trying some things, I took off the vacuum of both the blow by valve and the EGR and plugged the holes. Because then I wont get the black in my manifold. Which has been working for 2 days now even though its only a temp fix. I think maybe the O2 sensor or EGR could be a cause?

 

[RE2Master]

You have a failing PCM that they know about but refuse to tell you. This is how it is here even for new people wanting to buy a 93-98 model GC no matter what package it is. The PCM is the #1 culprit for stalling, charging, and performance problems due to a faulty soldered mainboard. Whoever saild OBD2 was a godsend is a blatant fool as all OBD2 does is GUESS to what it THINKS is wrong in order for you to dump more money into a vehicle. How you can say it is a MFG installed scammer aide for dealerships and garages to make more money off you than needed for a repair. PLUS if the PCM has problems then nothing will show as error on the OBD2 as it controls it. Replace the PCM, on eBay for $250 shipped and pre programmed for your vehicle and you will notice a positive increase in everything. If a certified tech tells you I am wrong, find out first if they are Chrysler or Jeep certified and not dual, if anything doing with Mopar certification tell them to shut up. Good luck fixing your Jeep.

 

[Dominic]

Your symptoms sound a little worse then mine but I would check all your plugs and wires carefully. A few years ago I had a crack in a brand new spark plug wire boot and it was arcing and causeing stumbling at speed. I have also had a cracked spark plug that caused similar syptoms.