car sputters on acceleration and dies after very long idle

[dmr]

For a while now, my 1987 Grand Am has had a very slight hesitation when I accelerate. It has gotten to the point where it now sputters and acts like it is going to die when I accelerate from a dead stop. After a few seconds of acceleration, the engine kicks in and acts normal again. The car idles normally.

It also is very hard to start after short trips, unless I let it sit for 20 or 30 minutes. The engine cranks, but refuses to turn over.

Also, if I let the car sit and idle for an extended period of time (again, 20-30 minutes), the check engine light comes on and the car starts to sputter and eventually dies. It refuses to start until it sits for 20-30 minutes.

I have changed the O2 sensor but that didn't seem to help. The engine has somewhere around 130,000 miles on it and we had the fuel pump replaced around 1995 (I assume they also replaced the fuel filter at that time)

Any ideas?

Devin

[94grandam]

I recently fixed similar problems so hopefully this will help:

This is a '94 Grand AM with 150,000 miles.

Basically, I had somewhat of the same problem. The car would idle rough (rich), it would buck/jerk during acceleration and also in a hard deceleration, it would even accelerate up to 30 mph on its own when in gear!

I started by replacing a bad Throttle Positioning Sensor (about $20) that was creating a check engine light, but this only worked temporarily.

I later came to realize that the heater hose comming off the Vent Oil/Air Seperator going back into the Intake Manifold was cracked on one side and even had a hole in the other. This was causing a pressure/vaccum failure. All the hoses were in pretty bad shape so I replaced all of them for the cost of just a few dollars and it took only about 20 min. (You can pick these up at any local automotive or hardware store.) Now the car is running strong with no more idle problems or unwanted acceleration.

One way you can test this theory is to spray some carburator cleaner around the hoses. If the engine dies, then you have a vaccum leak in the hose, though you may not be able to see it. Depending on how your engine is set up, you will either have the Vent Oil/Air Seperator (black plastic box w/ hoses connected), or a Positive Cranckase Valve system. I would focus around any hoses going into the intake manifold. If you have a PCV system like most cars, it could be a matter of a bad valve.

Another suggestion I have is to remove the Idle Air Control Valve from the Throttle Body. This builds up with carbon and can affect the amount of intake air comming in. Clean out the carbon buildup and then make sure the IACV is set to the proper depth. You should find the appropriate depth setting in a good automotive repair book such as a Chilton or Hayes. If you don't have one of these books, it's a great tool and definitely worth the investment.

Other than the Fuel Filter, as you mentioned, I might check/replace the Spark Plugs. That may even help your starting problem.

There's not really anything left that should affect the idle that I can think of, so hopefully one, or all of these tips will fix the problem.
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I also had the "dead-start" problem you described. The engine would either crank the starter and not turn over, or it would act as if it had a dead battery. And with the same result, once you let it sit for a while, then it would decide to start. This was an intermittant occurrance that got progressively worse over time.

I first suspected a bad starter, but hesitated to remove it because I would have had to remove the intake manifold to get it out. The battery needed to be replaced anyway, so I exchanged it with a battery that provided much more cranking amperage. Unfortunetly, this didn't help the cranking problem.

As it turned out, I had known for some time that the A/C Compressor was going out, but it wasn't until the compressor eventually siezed that I realized the relation of the two problems. Compressor got worse = Engine not starting properly. The engine had been fighting the compressor in order to turn over. I know this may sound like a long shot but I would possibly consider it because once I put in the new compressor, I totally eliminated the starting problem.

Again, I hope this helps.
Good Luck!

Brad