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1985 pontiac fiero gt auto v6


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nbombjesus
Novice

Nov 1, 2006, 2:52 PM

Post #1 of 5 (3468 views)
1985 pontiac fiero gt auto v6 Sign In

My 1985 pontiac fiero gt auto v6 is hesatating when shifting itself...i just did a tune-up on it and put a new battery on it...and still the same thing. so i have no idea what's wrong with. If i drive the car for a about 30 minutes to warm up it seems to stop doing the hesistating but it i have also noticed that i lost some horsepower. any help would be appreicated thanks!!!


DanD
Veteran / Moderator
DanD profile image

Nov 2, 2006, 2:48 AM

Post #2 of 5 (3409 views)
Re: 1985 pontiac fiero gt auto v6 Sign In

I’m guessing at a vacuum leak; broken lines, intake manifold gasket anything that will allow unmetered air into the engine? The computer relies/assumes that all incoming air is through the throttle. A vacuum leak throws a wrench into the computer’s calculations and limitations.
A cold engine requires a rich fuel mixture; if this is a vacuum leak; the computer may not be able to compensate (add enough fuel). Once the engine has warmed needing less fuel the requirements fall back to where the computer can compensate for a leak?
How to find a vacuum leak is kind of a search and rescue operation; some leaks are easily found if it’s external but then there are the internal leaks.
I have a 3.1 Chevy in the shop right now; it came in backfiring because of a bad ignition module. Once the module and the backfiring were repaired the engine still was not running properly. We found that there was a vacuum leak but it’s not external that can be seen. The intake gasket had blown out on the inside of the engine; drawing air from the crankcase. Likely due to the excessive pressures caused by the backfiring.
So what I’m getting at is there’s no real way of explaining how to find a vacuum leak other then experience, knowing what to look for and of course a bit of luck.
I’ve only spoke of vacuum leaks but there are hundreds of other reasons for a cold hesitation that again takes experience and equipment to find.
Dan.

Canadian "EH"






nbombjesus
Novice

Nov 7, 2006, 11:17 PM

Post #3 of 5 (3393 views)
different engine Sign In

Okay so i did some looking and my engine in my fiero is not the one that was factory installed. I figured this out when i didn't see the fiero logo on the top...and plus it isn't red....anyways I just did a tune-up recently as posted before. Is it possible that the engine i have in my car uses different spark plugs, spark plug wires, distibuter rotor..and cap? i am not too sure what king od engine i have...but it fits just like the fiero engine would...but it's it.


bryang
New User

Nov 9, 2006, 12:27 PM

Post #4 of 5 (3382 views)
Re: different engine Sign In

What kind of engine is in it is it a v-8 v-6 or 4 banger. I had a gt once and the problem that I had was the injectors had popped a fuse. Try checking all the fuses. They are located under the dash on the drivers side above were your shin would be if you were sitting in the car. Good luck trying to find a comfortable possition to work in to do this.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 9, 2006, 1:08 PM

Post #5 of 5 (3381 views)
Re: different engine Sign In

Back to top the person said it was a V6. I don't think a V8 was available, T







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