What could cause rough running, and

What could cause rough running, and stalling when engine is up to operating temp + some time?

1996 Caravan, 3.0 3 spd auto trans. Van has run fine for the last 3 years that I've owned it. The slowly developed hesitation, and stalling. At first it would only happen occasionally, then progressively became worse. Engine would die and not restart immediately. Would always take 1 - 2 minutes to restart, like computer was resetting itself. Though stalling issue progressively became worse, the other issues remained constant. Would always start and run fine till operating temp reached, and then about 15 to 20 minutes it would hesitate and stall. Never start immediately, but always after 1 - 2 minutes.

Replaced fuel filter, sprayed throttle body with carb cleaner, (no change in symptoms) and had codes checked. Came up will code MIL 11 or Generic Code P1391 (Intermittent loss of either camshaft or crankshaft position sensor). Replaced camshaft position sensor. Symptoms remain, but Van will now start immediately, and if given more fuel when hesitation is noticed will remain running. Still showing code 11 or 1391 when codes checked.

The constant symptom is still temp related. Always starts, and runs fine until at operating temp plus 15 to 20 minutes. Then hesitation. Now if given some fuel at hesitation it will smooth out and run fine for a bit, then hesitation again, and so on. If stall occures it will restart immediately and run fine for a short time then the same symptoms repeat.

I really need some help. Local mechanic hasen't a clue, except to throw parts at the car. Any one else have this?

Thanks
Ron

What could cause rough running, and stalling when engine is up to operating temp + some time?

1996 Caravan, 3.0 3 spd auto trans. Van has run fine for the last 3 years that I've owned it. The slowly developed hesitation, and stalling. At first it would only happen occasionally, then progressively became worse. Engine would die and not restart immediately. Would always take 1 - 2 minutes to restart, like computer was resetting itself. Though stalling issue progressively became worse, the other issues remained constant. Would always start and run fine till operating temp reached, and then about 15 to 20 minutes it would hesitate and stall. Never start immediately, but always after 1 - 2 minutes.

Replaced fuel filter, sprayed throttle body with carb cleaner, (no change in symptoms) and had codes checked. Came up will code MIL 11 or Generic Code P1391 (Intermittent loss of either camshaft or crankshaft position sensor). Replaced camshaft position sensor. Symptoms remain, but Van will now start immediately, and if given more fuel when hesitation is noticed will remain running. Still showing code 11 or 1391 when codes checked.

The constant symptom is still temp related. Always starts, and runs fine until at operating temp plus 15 to 20 minutes. Then hesitation. Now if given some fuel at hesitation it will smooth out and run fine for a bit, then hesitation again, and so on. If stall occures it will restart immediately and run fine for a short time then the same symptoms repeat.

I really need some help. Local mechanic hasen't a clue, except to throw parts at the car. Any one else have this?

Thanks
Ron


Sounds like the fuel filter is clogged. HAs it been replaced lately? :sunglasse

yes, replacing the fuel filter was the first thing I did.

Throttle position sensor, EGR valve, Air temp sensor, Idle air control valve, clogged Catalytic converter.

They may not throw a code, either, since it runs fine sometimes, it will automatically clear the so called stored codes, especially if your battery is weak (comes up with a 12 all the time).

Also, it may just need "combustion service" which sounds like BS, but it fixed mine once!

:)
slantsixness

"combustion service"? What do you mean?

I too am uncertain to what "cumbustion service" is???

Mine - a '95 Plymouth Voyager with the same set-up has a similar problem as indicated in my post of 7/10/04: 'Erratic Idle..........'

I noticed that you sprayed the Throttle body with carb cleaner!!
I have always heard not to - due to various plastics that are used within are affected by the chemical [ie; IAC unit 'pintle seat' newer versions are green in color (being plastic) and does deteriorate with carb cleaner causing a rough surface and pits] therfore I've never used it on any throttle body. I replaced mine with one from a Junk Yard (Man's Mall) that is all metal (can't trust the plastic one!).
You may wish to as well - New ones can cost a lot ($75.+) but in the Man's Mall maybe $5.

I have NO Codes coming up to point my way!
At first with mine the IAC unit is what I concentrated on [Carbon/dirt build-up around the seat in any throttle body (TBI) usually creates an 'Up-down' idle fluctuation] cleaned it - no help, replaced it with a metal one - still no help (a little bit though).
I now believe it to be strickly an electronic malfunction of somekind?
I have checked all 'grounds' for good contact and their presence - still no help! [aluminum is not as good of conductor as steel - so all straps (OEM) should be intact]
My next step is the O2 sensor, being that the problem is created at normal operating temperature (N.O.T.)[O2 sensors begin to operate when they reach about 660 degrees (N.O.T.) and basically runs everything else] and I will once again pay a visit to the Man's Mall and acquire 2-3 of these to replace.
[The O2 sensor has fine thermal wires within its caseing and if it has been subjected to excessive water or gas can deteriorate but still pass its minute voltage - checking good]

To all this, we may be able to help each other out here along with the aid of other AF members and conquer this problem!

In hope that I've helped!?
Rich

"Combustion service" cleans out the plenum, and supposedly the valves and combustion chambers in the engine.

Look, it's what the dealer said to do under warranty. It worked. They would have a better description than what I think is just "smoke and mirrors".

I've used carb cleaner on my whole systems, and never hurt the IAC, or any other sensor. How much are you using to damage the "so called" "plastic" parts, which are not plastic. Glad bags are plastic. Straws are plastic. The IAC is a composite. Most of the sensors are composites. And "Legal" carb cleaner wont hurt them.

Really. And it really is just that simple.

Clean it (the plenum and associated areas) and your "woes" will go away.

Whens the last time you changed the spark plugs? Jacked up plugs will cause hesitation, missing, and you could really fuck your entire engine up.

going through the forum, I notice a common theme. I have the same prob. only up to normal operating temp, my codes that keep popping up are p0403, and p1391. First is EGR fault, second is camshaft pos. sensor. I changed the EGR assembly and had the same problem, pulled it and put in the old. You said you changed the camshaft pos. sensor, alot of threads are saying it's the crankshaft pos. sensor as the fix. Have you tried this also?

(I also did the fuel filter, and new coil to no avail.)

On the 3.0 Mit engine, you probably have a vacuum leak or blown head gasket. That engine is junk, has always been junk, don't know why people say they are great, unless they like to work on engines every other week.

the early 3.0's had some issue but the later 3.0's mid to late 90's are actually pretty good than having to replace the timing belts . Have 120000 on mine and it still runs good . Could be a fuel pump problem , has the pressures been measured after it has been warmed up ?