Compression issues & black smoke on start up


Asked by Jul 15, 2016 at 11:27 PM about the 1992 Pontiac Grand Prix

Question type: Maintenance & Repair

Ok I just had my 92 grand prix 3.1 engine
rebuilt.'s not running right! It's a long
story so stay with me. First it sounded like a
drag racer when it got started. Then a
cylinder had bad compression that suddenly
turned to good compression (40psi-150psi).
Also had a faulty fuel injector dumping too
much fuel. So I got new fuel injectors & got a
valve adjustment. The car sounds better but
can still hear a light pinging noise plus I saw
black smoke on start up. Now the
compression issue has returned. First it's it's good again. Oh yeah it's not
the same cylinder doing it either. First it was
#5 then #1. Why would compression
fluctuate? Why am I still using too much
fuel? If the engine was properly rebuilt why
are these issues accruing? Obviously it
wasn't properly done. Lol. But I want my car
repaired & selling is not a option! Anyone
have a idea on what's wrong? Really
confused about the compression.....

2 Answers


The timing chain might not be timed correctly


If the rebuilder also installed it in your car, then I think its their problem, not yours. Drop the car off at their shop and tell them to call you when its running right. If someone else installed it then its more complicated. It could be any number of electronic or tuning issues totally unrelated to the rebuild. The engine itself might be fine, although the fluctuating compression seems suspicious. It will be up to the installer to pinpoint the problem and then you can decide how to address it. Putting a new engine in an old car is never a good idea. Hopefully the lesson you are learning won't become too much more expensive than it already has.

Your Answer

Add photo

Related Questions

Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Reputation 3,690
#2 Tom Demyan
Tom Demyan
Reputation 2,450
#3 munron
Reputation 1,960
View All

Related Models For Sale

Used Pontiac Bonneville"
860 listings starting at $1,450
Used Pontiac Grand Am"
2,009 listings starting at $1,995
Used Ford Mustang"
720 Great Deals out of 41,405 listings starting at $900
Used Chevrolet Camaro"
796 Great Deals out of 38,874 listings starting at $2,650
Used Nissan Altima"
1,407 Great Deals out of 87,808 listings starting at $1,195
Used Nissan Maxima"
463 Great Deals out of 24,164 listings starting at $800

Used Cars For Sale

2008 Pontiac Grand Prix For Sale
16 Great Deals out of 556 listings starting at $2,495
2007 Pontiac Grand Prix For Sale
597 listings starting at $5,500
2006 Pontiac Grand Prix For Sale
6 Great Deals out of 791 listings starting at $2,950
2005 Pontiac Grand Prix For Sale
5 Great Deals out of 505 listings starting at $1,972