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98 Stumbling when cold

B

bvillebud

NAXJA Forum User
Location
Berryville
I have a 98 with about 125K miles. When starting out with the engine cold (mornings, after work, etc.) the car will sputter and stall between 1K and 2K RPM’s for a minute or two until it is warmed up. Once warm the Cherokee runs perfectly. The car won’t throw a code (which is making me crazy) and I have replaced:

Fuel pump
Fuel filter
Coolant temperature sensor
Throttle position sensor
Idle air control
Plugs
Wires
Distribution cap & rotor
Coil

I am at my wit's end and would be eternally grateful for some insight on this problem!
 
I don't know if this could be your problem and I'm sure someone with more expertise will chime in but I had a similar problem on a Toyota Celica I have. It ended up being a crack in the rubber intake boot that was flexing as the engine moved. When cold, the crack was more prevalent and it would duplicate the symptoms you're describing. Once warm, the rubber would expand eliminating the leak. I would check all your hoses and vacuum connections to make sure you don't have a leak somewhere
 
Clean the throttle body out.
 
bvillebud said:
will do, but wouldn't it happen all the time if it were a TB?
Click to expand...
Nope, could be crud around the idle air controller or the map. Best way to do it is remove the throttle body and take into the workbench, remove the sensor and give it a real good scrubbing with a good decarboning stuff. I say remove the sensors because they are plastic and some of the carb/injector cleaner eats plastic.
 
Well I'm back. I replaced my TB with a bored TB, and it is still stumbling at around 1100 RPM when cold. So what the heck is next?? Could the MAP be going bad? Again this only happens in the fist minute or two when cold. No codes, & I'm getting tired of replacing parts.
 
bvillebud said:
Well I'm back. I replaced my TB with a bored TB, and it is still stumbling at around 1100 RPM when cold. So what the heck is next?? Could the MAP be going bad? Again this only happens in the fist minute or two when cold. No codes, & I'm getting tired of replacing parts.
Click to expand...

Disconnect the battery and touch the two DISCONNECTED cables together or let it sit for 30 min. Then reconnect and take it for a 45 min drive. It will force the ECU to relearn it's settings, worth a try and costs nothing, I've seen some odd problems solved this way.
Just so we are clear on this, DISCONNECT THE BATTERY, put duct tape over the two battery connections, remove it from the vehicle, put the battery in the kitchen, then go back out to the jeep and touch the negative and positive battery leads to each other, go retrieve the battery from the kitchen and put it back in.

I'm just covering all my bases here, some may figure they can do the same thing by just laying a long enough wrench across the battery to accomplish the same thing. DON'T DO THAT... :D :D :D :D :D
 
No dice,

Maybe it is time for a trip to the stealership, but I can't see how they are going to do anything different...


RichP said:
Disconnect the battery and touch the two DISCONNECTED cables together or let it sit for 30 min. Then reconnect and take it for a 45 min drive. It will force the ECU to relearn it's settings, worth a try and costs nothing, I've seen some odd problems solved this way.
Click to expand...
 
This will sound really off the wall, but I experienced a similar problem with my 98...it turned out to be a vacuum leak with the brake booster, which also had a tendency to "self-seal" after warming up. Strangely, my 89 also did this back in the day and I never thought to look there until I woke up one sub-freezing morning to find my brake pedal would barely move...I had recently done some deep diving and the vacuum leak filled my booster can with water, which then froze nicely.
The dealership will probably end up charging you a fortune replacing all the other things you mentioned having replaced. Unless you get one who's really sharp with the pro scanner, most of those guys generally chase their tails. ( my apologies beforehand if anyone takes offense, but thats been my experience every time).

Rich
 
I thinik I have found the issue. I was under the hood with the engine running and suddenly the EGR valve line (at rear of the valve cover with the line going to the intake manifold) went flat (vacume). I think the EGR is going on me.
 
Don't think '98 has an egr. Have you checked the Inlet Air Temp sensor? And make sure that the front tube goint into the valve cove is clear. If this blocked up, it could make the other hose "go flat".
 
Thanks winter - I finally feel like I'm getting somewhere. OK so where is the inlet air temp sensor? I'll check the front tube tomorrow am.

winterbeater said:
Don't think '98 has an egr. Have you checked the Inlet Air Temp sensor? And make sure that the front tube goint into the valve cove is clear. If this blocked up, it could make the other hose "go flat".
Click to expand...
 
so, I subscribed to the thread, having the same problem, and this afternoon, as I only had a few minutes, I pulled the ol' 'seafoam' trick. So far, so good. betsy is an 88, but she still stumbles out of the gate. After I let it cool down, the hesitation got better (or worse, how you look at it) and is alot more responsive to my ever gentle gas foot. might be worth a try...
 
Has anyone had any success w/this? Last time I had similar symptoms replacing the o2 sensor fixed the problem. I thought replacing it would have fixed my problem again but it didnt this time.
 
i have the same problem with my 94XJ Sport. No egr valve and today i tried 3 different brand new idle air control valves, all of which as soon as i started the jeep would only hold an idle of 3200RPM or higher!!

my stall/stumble problem only occurs when the jeep is cold. after warmed up its fine. The cps was replaced 2 days ago. (different story, crank no start, u all know the deal...)

there is a sensor on the intake manifold closest to the firewall, it probably is the air temp sensor, im not sure since i havent looked into it yet. it will be next to be replaced, then map.
 
good luck! I've replaced my water temp sensor, AIC, TPS, coil, plugs, cap, rotor, Crank PS (code thrown), any vacume hoses that looked suspect, fuel pump & filter (code thrown), O2 sensor (code thrown), seafoam'ed the intake and STILL have the problem with no codes thrown.

Getting a little tired of the stumbling thing.
 
no is there a "how to" on a manifold leak check. I have a giant compressor (80 gal 220v) maybe that would be a little safer?

I'm leaning toward replacing injectors also but they are bucks; but I keep chasing this thing spending $$ like crazy with no fixes. It is getting frustrating.
 
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