95 grand prix backfires

pontiac

#1

My 95’ grand prix gtp recently backfired twice in a row while accelerating (normally, not hot-roddin’). Does anyone know what causes this? Could it be the spark plugs or the timing at all? Any info is helpful!! Thanks!


#2

How long has it been since the fuel filter was changed? It could be a fuel volume delivery problem as well as an ignition hiccup due to plugs/wires, or coils.

How long has it been since it’s had new plugs?
Another more obscure cause could be in the intake tract and may involve an air leak or bypass valve.


#3

I should have added that some of this era of GM vehicles with the 3.8 were a bit prone to plug wire problems.

Some of that could be attributed to leaving plugs in for too long an interval.
Misfiring plug eats up plug wire, which can knock out coils, etc.
It’s also one reason why I vehemently disagree with recommedations about leaving plugs in for 70k miles or whatever other ridiculous interval is specified.