Pontiac Grand Prix misfire

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  #1  
Old 11-29-03, 10:18 PM
ccambron
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Pontiac Grand Prix misfire

I have a1990 grand prix - V6 it seesm to run okay but at 3800 rpm it will misfire and will not go about 3800 rpm. Amy suggestions?
 
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  #2  
Old 11-30-03, 08:29 AM
darrell McCoy
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How long has it been since it has had a good tuneup? Does it set a code. Could be ign or fuel problem either one. I would lean toward plugs, wires or possibly coils.
 
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Old 11-30-03, 05:08 PM
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Could also be a vacuum leak. What speed vs. the 3800rpm are you running when this happens? Does it happen when you rev it sitting in park?
Billy
 
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Old 11-30-03, 05:21 PM
darrell McCoy
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Think Billy jogged my memory some. Seems some if not all GM pass car models had some type shutoff so you could not over rev them in neutral/Park. Least thats what another GM shop honcho told me.
 
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Old 12-01-03, 05:16 AM
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if it's a 3.4 L engine,

then it has rev limitation and the ignition is actually turned on and off...this is to prevent engine damage from overrevving with no load. so...are you just revving it up in neutral or does this occur in drive while moving down the road??
 
  #6  
Old 12-03-03, 12:30 PM
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3.8k rpm isn't fast enough for the rev limiter, is it?

My '90 grand prix with 3.1 has a limiter that won't let it rev above 5 or 6k rpm. And that's only in park or neutral with the vehicle standing still.

But if the engine is running great, except for that.... It probably is the rev limiter.

Jason if you really need to know pm Davo.
 

Last edited by davo; 12-03-03 at 02:00 PM.
  #7  
Old 12-04-03, 09:39 AM
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that's why...

...i asked if it has a 3.4 L engine...they are limited at about 4 grand...and factory tachometers are not notoriously accurate...the original poster was also asked if it happens while driving or sitting still in neutral/park...obviously he didn't post back and answewr our questions. the other obvious thing that needs to be mentioned here is that revving ANY engine with no load is NOT advisable as it is extremely hard on rotating parts to be accelerated and decelerated so quickly.
 
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