Warm engine restart rough idle stall

[badandy]

Okay guys...thinking cap time

Car 1988 CSX-T
Shel-Game Cal, +40's, 3 bar map, 255 pump...otherwise 100% stock engine (for now hehehe)...all mods are bolt on's currently (exhaust, intercooler, under drive, yadda, yadda...you guys know the spill)

This problem has only recently started occurring...no changes to the car have been made modifications wise. The problem occurs no matter what the gas or what the weather...purely dependent on if I cut off the car and restart it before the engine cools down.

Car starts up cold and drives fine...when I get back in the car and the engine is still warm...and I restart...it idles terribly belching black smoke out the back like it's running extremely rich. If I try and rev it it will just idle back down and stall out...same if I try and drive it. The only fix I have found is to give a little help with the throttle blade which will send the revs higher ='s no problem.

I'm not losing fuel pressure after shut down...and if the engine gets cool again it starts normal. I've been thinking maybe CTS but I have not seen any codes...I've also thought about vapor lock but I would think that would create a no start situation? When this situation happens I usually just shut the car off and try restarting it a few times and eventually it acts as if the idle speed motor catches the idle before it drops and I'm all good.

Anyway...the car runs fine otherwise.

Any Ideas?

[magtec]

any codes? i had one that did something similar, warm starts were rough and it only ran on a couple cylinders when it did start. after about a minute it would smooth out and idle like nothing was wrong. never got around to fixing it before the car was pastured. it always threw an EGR code (32, i think).

[badandy]

any codes? i had one that did something similar, warm starts were rough and it only ran on a couple cylinders when it did start. after about a minute it would smooth out and idle like nothing was wrong. never got around to fixing it before the car was pastured. it always threw an EGR code (32, i think).

No codes...and that's EXACTLY how it acts! I've never had any of my cars exhibit this before...I have heard of it though. My guess would be that due to there being no codes it has to be a mechanical situation (like a leaky injector for example). I've done a TON of searching the subject on this board and the one that used to be cool Those that had the problem never did come back and say what the fix was...that is if they ever fixed it.

[MiniMopar]

Could be a leaky injector or it could be high fuel pressure due to the big pump. Have you check the static pressure in vacuum? Some people have trouble with the regulator/return line not flowing fast enough for the 255.

It could also be a problem with the cal. Getting the startup fuel right can be a bit tricky.

[badandy]

Could be a leaky injector or it could be high fuel pressure due to the big pump. Have you check the static pressure in vacuum? Some people have trouble with the regulator/return line not flowing fast enough for the 255.

It could also be a problem with the cal. Getting the startup fuel right can be a bit tricky.

Injectors hold good pressure after shutdown...checked that already as that was my first thought.

I upgraded my return line to 5/16 and have very little restriction there.

Static pressure in vacuum is around 42-43 psi...as I was one of those people

I was suspecting the cal too but didn't have this problem after the cal swap initially.

Thanks for the suggestions

[magtec]

i forgot to mention that the car that i experienced this problem with had an '85 TI with '87 electronics. everything was pretty much stock. one thing i did notice is that the problem was more pronounced during the warm months. seemed less severe (and possibly didn't happen at all, can't quite remember) during the colder months. it also always threw a code for the air charge temp sensor (code 23, iirc). i replaced the sensor and it still threw the code, so i imagine there was a wiring problem. there may have been some bad grounds, too.

[badandy]

i forgot to mention that the car that i experienced this problem with had an '85 TI with '87 electronics. everything was pretty much stock. one thing i did notice is that the problem was more pronounced during the warm months. seemed less severe (and possibly didn't happen at all, can't quite remember) during the colder months. it also always threw a code for the air charge temp sensor (code 23, iirc). i replaced the sensor and it still threw the code, so i imagine there was a wiring problem. there may have been some bad grounds, too.

My problem is definately more pronounced in the warmer weather...and less when it's cold...which won't be fun come this summer if I don't track this down.

My air charge temp sensor has been deleted in the cal code.

I ordered up one of those ground wire kits from Cindy awhile back and installed it...should be good there.

Note of interest:

If I floor the gas and start it I have no problems...also, aside from not losing fuel pressure I know it's not an injector leakdown issue because if I shut down and restart immediately I have the problem...which wouldn't be enough time for it to flood itself with fuel.

Strange one here folks

[badandy]

I'm wondering if I need to take a look at the TPS values?...although I can't see where that would cause a starting problem as that should only cause a driveability issue.

I have noticed that a "stock" cal tends to rev up a little more once it fires up and then settle to an idle.

[MiniMopar]

I'm wondering if I need to take a look at the TPS values?...although I can't see where that would cause a starting problem as that should only cause a driveability issue.

I have noticed that a "stock" cal tends to rev up a little more once it fires up and then settle to an idle.

That's a sign that it too is getting more fuel than expected after startup.

[t3rse]

after you shut it off, pull the plugs and smell for gas

[badandy]

after you shut it off, pull the plugs and smell for gas

Will do, I have suspected it was fat to start with. I have the same issues as others with +40's flowing more than what they are rated. I will also drop my pressure back down and drive it and see if it repeats the issue.

[MiniMopar]

I have two sets of "+40s". One set I bought in '99 the other set I bought a few years ago. The newer set flows more like 58pph, based on how much fuel I had to pull out to get the same A/F at WOT when I swapped them.

[88_pacifica]

hmmm... is the FP rising excessively when cranking and then lowers when starting, but then reaching a normal rate when running? Basically, by cranking the motor is it sending a higher 'voltage' when warm or even a more pronounced amount to the pump? When was the filter last was changed? I would be curious to see if while cranking over if the rate of the FP rises dramatically. As for fuel related issues and black smoke, I would only see that the volume is large, but I would be interested in seeing what the injector pulse widths were as well on startup...

[badandy]

hmmm... is the FP rising excessively when cranking and then lowers when starting, but then reaching a normal rate when running?...

I don't have an in cabin fuel pressure gauge but will try and get someone to watch for me while I test that theory

Basically, by cranking the motor is it sending a higher 'voltage' when warm or even a more pronounced amount to the pump? When was the filter last was changed? ...

When a brand new tank and the 255 pump was installed at the same time.

I would be curious to see if while cranking over if the rate of the FP rises dramatically. As for fuel related issues and black smoke, I would only see that the volume is large, but I would be interested in seeing what the injector pulse widths were as well on startup...

I will either need a friend for a set of eyes/hands or a starter switch.

I bumped the fuel pressure down about 10 psi and warmed the car up by driving easily...watching the CEL for knock. Once the car was warm I immediately shut it down and cranked it back up...same thing happened. The RPM's just don't climb above 1,000. It's like the idle speed motor doesn't want to work at all...choking the car out. Once again...if I floor it and crank I'm good to go.

It has to be something that wouldn't set a code. I'm suspecting the idle speed motor after warm startup myself. Maybe I need to do the idle motr reset proceedure?

[MiniMopar]

You might want to check the minimum air adjustment:

http://www.knizefamily.net/minimopar...l#minairadjust

However, it still sounds like the calibration is putting too much fuel in. I had this happen, now that I think about it, on my first Shadow...a bone stock 87 T1. It didn't throw any codes, but the problem went away after replacing BOTH temp sensors (coolant and charge). I think the coolant sensor was out of range, but not enough to trip the code. It gave me trouble when cold, not hot, but it's worth a shot. Early T1s ate charge air temp sensors often.

[88_pacifica]

It has to be something that wouldn't set a code. I'm suspecting the idle speed motor after warm startup myself. Maybe I need to do the idle motr reset proceedure?

Shelgame is good and I notice his cals are typically not mentioned as problematic. In this case though I would compare the fuel tables before I started throwing money at the problem. We all KNOW that is the typical answer, but rarely the right one... I will be curious to see what comes of this.

The only other opinion I would have is not a common problem on TD's and that is that there is a gasket leak at the manifold. However, usually there is a strong fuel smell and the symptoms are lean issues and not flooding issues. Keep us posted...

[badandy]

*I think* that the cal is indeed rich at idle to start with...or I have a set of those higher flowing +40's that we have discussed previously...but I honestly don't believe that is the problem with this issue because it was not a problem after going cal/3bar/+40's.

Here's what I did:

To be sure all was good I made sure the car was:

A. Up to operating temp

B. I fired it up to be sure it would duplicate the issue I have been having...which it did

I shut the car back off and performed the minimum airflow reset as out lined (Thanks Russ). On a side note I remember Steve Calder doing this exact procedure YEARS ago and was in the back of my mind that this could possibly be my problem...but any way...I did the deed. Once finished I expected to get a check engine light like? I was able to turn the throttle stop back out quite a bit to get the idle down to the 500-700 rpm as instructed. This lead me to believe that the throttle plate was adjusted so that the idle air was all passing by the throttle plate and the idle air solenoid was trying to close to compensate....possibly causing the condition.

Once finished I shut the car off and cleared the computer and fired it back up. The car was indeed still warm and had zero problems I'll continue to check this out and post back with my findings.

Thanks to all

[magtec]

I had this happen, now that I think about it, on my first Shadow...a bone stock 87 T1. It didn't throw any codes, but the problem went away after replacing BOTH temp sensors (coolant and charge). I think the coolant sensor was out of range, but not enough to trip the code. It gave me trouble when cold, not hot, but it's worth a shot. Early T1s ate charge air temp sensors often.

it's been quite a while, but i'm fairly sure i replaced both the CTS and the air charge temp sensor on the car that had the problem.

[badandy]

I will probably replace the CTS and report back

[badandy]

Just thought I would report back in case anyone ever does a search on this:

Although I can't say for sure...I believe the issue was the startup fuel on the calibration I had. I swapped out some parts along the same time and it was better but still tried to do the same thing a few times...after cal swap it went away completely.