1991 Pontiac Sunbird 91' Sunbird losing acceleration, stran

AUTONERF

MEMBER
1991 PONTIAC SUNBIRD
4 CYL
2WD
AUTOMATIC
101,000 MILES

I have a 91' Pontiac Sunbird, 6 cylinder, 3.1 liter with 101,000 miles. Sometimes when driving, the engine will make a low rumbling sound and the whole car will shake like a space shuttle ready to lift off. When this happens it loses power, and doesn't accelerate smoothly.

The engine works fine sometimes. But as an example, tonight it was going as usual at 60 mph on the highway, when all the sudden traffic came to a halt. When I stopped the engine started doing it's low rumbling sounding much lower than normal. I tried flooring it a couple times when we got going, and it took longer than normal to kick into high gear.
Acceleration was just slower in general.

It seems to have the problem at random times at any speed. I just had the spark plugs replaced a few weeks ago and the oil leaks fixed.

Thanks for any ideas and help.

4 Replies

BLUELIGHTNIN6

MECHANIC
16,542 POSTS

First off, is your engine 3.1L or 2.0L? 3.1L would be a 6cylinder not a 4cylinder as you have listed.

Does this occur at higher speeds or lower speeds? It sounds like it is struggling for fuel when this occurs. How long has it been doing this? You may have gotten bad fuel or your fuel filter may be clogged.

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Thursday, November 13th, 2008 AT 11:36 PM

JAMES W.

MECHANIC
2,395 POSTS

I was down at Cape Kennedy once years ago hopeing to see a lift off. I asked the tour guide if I could take a ride. He just looked down, shook his head and walked away. I took it as a "no". Anyway, on to your problem. A few questions. When this shuddering condition exists, how long does it last? Does it go away by itself or do you have to do something? Is it at highway speed, or on acceleration or when? When was your last tuneup? Please advise.

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Thursday, November 13th, 2008 AT 11:37 PM

AUTONERF

MEMBER
2 POSTS

I forgot, it is a 6 cylinder. The rumbling engine sound seems to come and go, and could last for a couple minutes at a time. It's like the engine is being limited. It seems to go away by itself. It usually happens after I have slowed and then started to accelerate, but has happened at highway speed also. I did not notice anything before I got my last tank of gas, so hopefully that is the problem.

The spark plugs were replaced a few weeks ago. I'm going to have it checked out soon, thanks.

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Friday, November 14th, 2008 AT 12:03 AM

BLUELIGHTNIN6

MECHANIC
16,542 POSTS

I would go ahead and run your fuel tank to about 1/4 low and then run some fuel treatment in it with your next fill up. If this doesn't help, then you may need to have it checked at a local shop. Try the cheap route before going to the shop though. STP fuel treatment is around $3. Much cheaper than a shop.

You can also test the fuel filter by removing it and blowing the through holes (careful not to swallow any fuel that may be left on the filter) and if you can feel the air coming out other end it is good. Never a bad idea to just replace it though, it's cheap and gives you better gas mileage.

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Friday, November 14th, 2008 AT 12:28 AM