Engine Dieseling at shutoff
Thread Starter
TECH Enthusiast
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Joined: May 2005
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From: Orange Park FL
Engine Dieseling at shutoff My car seems to diesel when i shut it off. What would cause this. I run 93 all the time. My mods are lid, ported TB, Y pipe and catback. It did this when i first got it to and all it had was the lid and a cutout on the stock exhaust. I've also used some seafoam to clean and carbon out but it did't even smoke at all so it must be clean in there. So what could be causeing it to diesel?
Thanks
Jon
Thanks
Jon
You have to be getting fuel in there when it does it, find out from where? While it's running & hot (conditions it runs on in) pull the fuel pump relay & see what it does. Prolly wont run on then....
Thread Starter
TECH Enthusiast
iTrader: (3)
Joined: May 2005
Posts: 704
Likes: 3
From: Orange Park FL
Its not real bad like i think you guys might be thinking. Maybe the proper term is not diesleing but it does run on for like a split second. It does't run on and on but it does't just cut off like it should. It cuts of and then sound like its chugs for a second and sound not to good it's hard to explain but it does't sound right. The car runs strong but its just does't sound right when its shut off. My GF's car (99 Z28)does not sound like this it just cuts straight off. I'll look into the fuel pump relay.
Thanks
Jon
Thanks
Jon
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Verdad Gallardo I don't know how good seafoam is but I know that GM Top Engine Cleaner is good stuff I'd recommend trying that. Pour it in and let the engine bog down until you get the recommended dose poured into the intake and then shut off the engine and let it sit overnight for atleast 8 hours. Then start it and take it out and get on it hard. The only reason I say do this after you have done the seafoam is I've seen lots of times where someone used a product like that thought they had everything clean and the GM stuff cleaned it out. I always whenever providing input on something like this list the 1 or 2 things I would check first because I've seen enough to know what the more likely things are and carbon buildup is the most likely for this type of problem.
If that doesn't change the way it behaves then you may have injectors firing after the ignition is turned off, which will not be easy to track down and diagnose. if your cam sensor is not sending the correct signal it could cause the injectors to fire out of sequence with the spark and that could cause a problem such as this so be sure to check the signal its sending. If that doesn't get you anywhere take the car to a good dealership and have them check it out and see what they find. If they can't find anything then chances are you'll never figure it out yourself unless they are not very good techs or you get lucky and stumble onto something.
If that doesn't change the way it behaves then you may have injectors firing after the ignition is turned off, which will not be easy to track down and diagnose. if your cam sensor is not sending the correct signal it could cause the injectors to fire out of sequence with the spark and that could cause a problem such as this so be sure to check the signal its sending. If that doesn't get you anywhere take the car to a good dealership and have them check it out and see what they find. If they can't find anything then chances are you'll never figure it out yourself unless they are not very good techs or you get lucky and stumble onto something.
