Rockyd

Ok I have this going on now. The car runs great when the key is on bit when I got home yesterday and parked it I went to turn the key off and as soon as I did it tried to keep running! Key out of the ignition and in my hand it was TRING to stay running fOr about ten sec then finally died. It did rain and I'm sure more than a little more water was entered into the engine bay so could this be my ignition module not sure? Thanks in advance!!!

Turbok9

Is it dieseling? Like, erratic disorganized firing? Or is it smooth like she normally runs? If it's dieseling, make sure your idle speed isn't high, check for carbon throttle plate closes fully when the ignition is off.

Heh. Had a Corvair years ago that was so full of carbon hotspots it would diesel so bad you could pop into 7-11, grab a slurpee, and just turn the ignition to 'on' without needing the starter....

Rockyd

That's exactly what it's doing I'll look into the cArbon build up

camaronewbie

In my experience, the 'deiseling' effect is usually a result of bad timing - so you might check your timing. Remember to disconnect the EST wire before checking/adjusting the timing, and to reconnect it afterwards.

Schurkey

Does turning off the ignition NOT disable the fuel injection and fuel pump?

Perhaps I'm wrong, but since I'm sure turning off the ignition should positively kill the fuel, I'd be investigating how the injectors 'n' pump are still operating. Are they pulling power from some kludge wiring?

No fuel...no dieseling.

camaronewbie

As long as there is oil pressure in an FI car, the oil pressure sending unit will keep the pump running and feeding the injectors, regardless of the ECM or anything else. The OPSU gets direct battery power always regardless of the key.

So again, I'd look into a timing issue. I've never seen a car "deisel" taht didn't have some kind of timing issue.

Schurkey

So the ECM fires the injectors even with the ignition "off"???

camaronewbie

No, I guess not. Regardless of any technical debate on whether or not it's possible, I'm just saying that deiseling is typically a timing issue. It's nothing I can prove, nor do I desire to. Takes 10 minutes to check/set timing, so it was something easy for the OP to check. Just because I can't explain a reason why it's a possibility, doesn't mean the possibility doesn't exist. There's many things I intuitively understand, yet I cannot fully explain.

Like on a non-cc carbed car - in theory - doesn't the coil not get any juice after the key is turned off? Yet they will deisel as well from a bad timing issue will they not?

And, after more thought - whose to say the ECM can't fire an injector with key off? ECM gets power from the same direct battery connection that the OPSU gets power from - that 20amp fuse tucked between the battery and the fender. That's why we have to disconnect the battery for more than a minute to clear codes - the ECM ALWAYS has power and is ALWAYS working, regardless of the key.

The ECM will run the fuel pump as long as it gets a signal that the ignition is still operating (that's how it runs the fuel pump - it's programmed for the 2 second prime when key initially turned on, then after car starts and is running, it sesnses a constant ignition and thus runs the pump). So maybe the ECM also fires the injectors off the same circuitry that it's running the pump from, which has nothing to do with the key at all.

I don't know - I'm no expert, and not in a mood to debate "how it should or shouldn't" work - things happen, regardless of whether or not in theory they should, such is life. That's why someone made a butt-load of cash off the bumper sticker. Checking timing is an easy reasonable place to start, regardless of any theory otherwise.

//<86TA>\\

iTrader: (14)

try using better gas. that generally will help this too.

this can be caused by bad gas, improper timing, or carbon buildup.

Schurkey

Yes, checking timing is easy and may be productive.

That's EXACTLY why they call it "dieseling". There IS NO SPARK, the engine continues to fire based on overheated combustion chamber causing spontaneous ignition of the fuel/air mix. Timing doesn't make a bit of difference AFTER the ignition is turned off; but if the incorrect timing leads to an overheated combustion chamber, then incorrect timing can cause dieseling indirectly.

That's also why killing the fuel positively prevents dieseling--the engine can run (sort of) without spark, but it CAN NOT run without fuel.

Yup. Possible. Not likely, I think. I would expect that losing the ignition power "should" also kill the injector pulses--but I don't know for sure. At least on my '88 TBI pickup, the ECM has TWO power sources, one is powered by battery 24/7; the other is switched with the key. Clearly the ECM knows when the ignition has been turned off.

No, mechanical things work exactly as they're designed and built. The question is whether they're designed and built to do what is intended. Of course, if aftermarket modification or some sort of defect is involved...again, the mechanical device will function exactly as theory would predict as long as the theory accounts for the revised operating conditions. There is a REASON why the engine is dieseling; we just haven't figured out why...yet.

Yes, it's worthwhile to check out the timing. In MY experience, overly-fast idle speed is more responsible for run-on than timing, and overly-hot operating temperature is also a contributing factor. In this case, idle speed should be controlled by the computer and shouldn't be a factor here.

Turbok9

Being it's a TBI and not a TPI, it may be dieseling on residual fuel in the intake manifold. Couldn't do it long of course, but since TBI's inject into the throttle body and not directly into the cylinders you've got residual fuel in your intake when you shut the car off.

one92rs

iTrader: (5)

remove the air cleaner with it running and see if you have an injector or the injector pod leaking fuel down in the intake. also shut it off and see if there is any fuel leaking anywhere from the injector pod as well.

Rockyd

sounds good guys and i am open to all ideas. i did check the timing and nothing has changed there i also looked for carbon and was all clean. i will take the cleaner off and see how it reacts
like i said in my OP water did get into the engine bay not like i ran into a flood but my ss hood had small slots in the scoop and the rain caught me coming home i was wondering if Ignition control module could be causing this. im stump right now thanks for all the advise guys and as soon as i find this problem i will post my results

one92rs

iTrader: (5)

remove the distributor cap and spray it with wd40 and reinstall.

Rockyd

ok i checked out the car today and well i did notice my injectors seem to be letting a little more than normal fuel flow i will have to change them in the near future but when i did turn the key off i noticed that the injectors were still firing not the greatest but enough to keep it DIESELING so im stumped right now

klferguson26

Its a timing issue...seen it a thousand times. No constant fuel supply but there is still atoms and vapors that can cause it to stutter but not fully run on compression and heat in the cylinder...that is also why it is usually followed with a pop through the carb/tb. Have the same issue in my carb'd car...timing is off.

Schurkey

Might want to check the dates of the posts you reply to. I'm reasonably certain that in the almost four years since he posted, he's either solved the problem or stopped trying.

Rockyd

Well I guess that would be my fault as I thought I did post the results of my find. Thanks for the comment but all in the end a vacuum leak was to blame. If I remember it was off the vacuum ball area and charcoal canister. Fix that line and haven't had a problem since.