1989 Pontiac Bonneville LE 3800 CC Motor Injector MisFiring 5 cylinder Why is this happening?

Tiny
WILDERTRACY
  • 1989 PONTIAC BONNEVILLE
  • 44,000 MILES

I have a 1989 pontiac bonneville LE 3800 that I can't figure out.
It's on and off mis-firing on cylinder 5. Is this something that is normal and what is the problem?
thank you for any information you can give me to alleviate this problem.
with regard,
Tracy

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Tuesday, September 20th, 2011 AT 1:50 AM

3 Replies

Tiny
MHPAUTOS
  • EXPERT
  • 30,790 POSTS

Check compression, plug, lead and vacuum leaks at that cylinder, start here.

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Tuesday, September 20th, 2011 AT 2:51 AM
Tiny
JB85128
  • MEMBER

We almost have the same problem. My 97 bonneville has been having issues with a misfire on cylinder #4. What I have learned so far is that a misfire on one cylinder is most likely a fouled spark plug, bad ignition wire, clogged injector or possibly bad compression such as a burned valve. There may be a slight possibility of a bad coil, but if the coil pack fires two different cylinders then it should misfire on both. I figure a person can change the coil packs around to see if the misfire moves with the coil or stays on the same cylinder.

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Saturday, October 1st, 2011 AT 2:25 AM
Tiny
WILDERTRACY
  • MEMBER

I have looked at most of those options you both speak of.
I think it may be the computer board.
After I put the dash back together (which will take several hours) I plan on just taking it to a shop to get it fixed.
Good luck to you and many thank yous for answering!

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Sunday, October 2nd, 2011 AT 2:09 AM

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