QuestionHi john
Thanks for taking the tjme to look at this
the 1994 cutlass clais sl 3.3 liter car that I
am working on. It has a driveability problem.
There are no codes and no service engine light
being displayed. The car is fuel injected and
stumbles at idle and exceleration. At highway
speed the engine runs jerky almost like there is
water in the fuel ? It seems to be getting worse
every day. I have changed out the spark plugs as
they had high miles. My next guess will be the
fuel filter. I installed a new fuel pump and
filter last July. John what are your thoughts on
this type of problem ?
Thanks again for your expertise.
Peter marshall
AnswerPeter,
Surely there could be a number of problems but normally a misfire like this which is triggered by opening the throttle, putting a load on the ignition system is a plug wire type problem. It could be a wire burned inside near the spark plug boot or a rip in the insulation at the spark plug boot. I use a spray bottle to wet down the wires in this area when the engine is running and often no always the engine will begin to misfire because the water acts as a bridge to ground and if a spark plug boot is a skew it will show up sooner. If not it will make the problem happen sooner and more often. The problem with the plug boots is a well known thing within the business and the holes are often too small for "normal" people to pick out. That would be my best guess along with pulling the plug wires off the coils and looking for signs of black crud or something that looks far different than the others. This would normally be a burnt wire at the coil and I just replace the wire/wires and sand down the junk off the coil terminal. Thats what comes first. PS a fuel filter would not cause an engine to misfire sharply it would cause the problem to act in a more balanced way.
