1995 olds cutlas

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  #1  
Old 03-08-05, 07:26 PM
gman56
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1995 olds cutlas

Car info:
3.1 6cyl

Live in midwest. After car sits out it starts great runs smooth. Go to work on freeway park car leave work get home. If I only leave the car sit 1/2hr or so, when I start it runs rough. Before fuel injection and electronic ignition It feels as though it was double firing missing. If i step on the gas it sputters and spurts then smoothes out. Its then great. If you park and wait the hour or more there is no problem. This happened a few years ago had it all checked. Olds said nothing wrong. Used a cleaner and told me not to use BP or Sunoco. It seemed to work, but now its doing again. I changed plugs, wires, pcv and air filter plus used an injector cleaner.

Any thoughts? As long as I dont turn off after hot, it would great until the gas runs out.

Thanks for any help.
GMAN56
 
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  #2  
Old 03-09-05, 07:49 AM
Lugnut's Avatar
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Location: Kansas City, Missouri.
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Your symtoms are a bit sketchy, but I'll take a wack at this.

A leaking injector (TBI) could cause this. You can think of a leaking injector as an injector that very slowly drips one drop at a time, after the engine is stopped, similar to a very slow kitchen sink drip after the faucet is shut off. But the leak would have to stop dripping after a short period (say 15 min), perhaps due to the the fuel line pressure being equalized.

If so, this would leave a puddle of gas in the intake manifold that would imitate a extreme fuel rich condition. This could cause the engine to sputter momentarily until the heated O2 sensor feedback would correct it, and in short order the puddle would be gone.

Longer sitting times, an hour, might be just enought to evaporate just enough of the puddle to minimize the start up sputtering, however the engine would probably be starting very rich, but you would not notice it and think all is well.

Shorter sitting times would not allow a large enought puddle to form, hence no sputtering. But I suspect the engine would also be starting rich and you simply would not know it.

Pulling trouble codes during the sputtering (or anytime) might reveal a intermitent rich fuel condition. Since it corrects itself, it would not trigger the dashboard trouble light.

You may be able to see and smell this puddle after removing the air intake, say about 30 min after you stop the engine. If you can't see the puddle thru the throttle body, then you definately should be able to smell the heavy gas odor.

Perhaps the Sonoco gas has additives (detergents mainly), or lacks detergent additives that contribute to the leaking conditions and the dealer may be correct in his advice.

You said that when the dealer cleaned the injector a few years ago, the sputtering stopped. This is consistent with the idea that you have fuel related problem. A can of fuel injector cleaner in the gas tank will not remedy this problem.
 
  #3  
Old 03-09-05, 02:57 PM
gman56
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Thanks for the reply lugnut,

I may not have explained well. The shorter the turned off time the worse the re-start is. I follow what you are saying with a long shutdown gives the extra gas a chance to evaporate. The one thing that happened just today. If I sit waiting for someone (running) for more than a couple of min. I get the very rough running for a moment when I pull out. Again its not on the high end. The car goes like hell on the freeway with no hesitation. I will take the time to check your theory about the puddle of gas. (leaking injector)

Thanks again
gman56
 
  #4  
Old 03-09-05, 04:19 PM
poof
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If the engine is a 3800 v6 you may have a fuel pressure regulator problem,there has been a safety recall on that.If you want to challenge it: With the engine off for 20 mins. pull the vacuum hose off the regulator and check for fuel in the line,if present the valve is bad,this line should be dry.When there is fuel in the vacuum line the engine gets semi flooded on warm start up,also if its bad and is on the recall list the dealer will replace it free,Good Luck
 
  #5  
Old 03-10-05, 07:04 AM
gman56
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Thanks poof,

Now I have 2 good ideas to check this weekend. I appreciate the help.

Thanks
gman56
 
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