Questions and Answers

Chevy Cavalier Is Missing Q. Thanks Vince, this is a long story about this car, but I will try to keep it short. 1995 Chevy Cavalier, 2.2 liter, automatic transmission, 87,000 miles. I bought this car "pre-owned " in April. When I tried it out it ran real well with the exception of a few minor problems including a little miss. I thought I could correct it with new plugs, wires and some injector cleaner.

It also had occasional smell of gasoline, but the dealer tightened the clamp on the air duct at the throttle body inlet and it stopped gas smell. I drove it for one week when I discovered the head gasket was oozing coolant (externally) in front of #4 cylinder. The next day it quit running due to ignition module failure.

Even though I had purchased an extended warranty, I got the runaround from them and had to pay for it all. The garage owner who did the repairs is an old friend and he assured me that the head was sent to the machine shop and there were no cracks in it and the only problem was the gasket and module.

When I went to pick it up he said he noticed the miss and suggested new wires, plugs and some injector cleaner. None of these worked. The miss only occurs while idling (cold or warmed up ) or when driving on flat highway, or when decelerating. When going up a hill or accelerating there is no hesitation or any sign of a miss at all. It has plenty of pep and gets 30 mpg.

I decided to check compression according to the Haynes manual and found on the first stroke the reading would be 150 psi and then go up to 175 to 178 psi on each cylinder.

Question: would that rule out cracked head, burnt valve, or cracked piston ring? Now I've noticed when getting gas there is no hissing when loosening the cap ( no tank pressure).

Question: could that cause the problem? I checked out the engine control schematic and saw where the crank position sensor plays a big role in timing and firing.

Question: could that sensor have an intermit ant cut out causing the problem? I'm trying to rule out the BIG stuff (head, rings and valves) before I go any further with repairs. I deeply appreciate your reply and willingness to help out in this situation. I'm looking forward to spending more time in this car than under or on top of it.

Thanks,
Phil

A. Sounds to me like you need to look at the injectors. Have a coil and balance test done to make sure all are okay. If you could narrow this down to a particular cylinder it would be simple. To rule out spark, they make a spark tester that is put in between the plug and wire. It lites a little bulb when plug fires. Maybe one of these on it a cylinder at a time will help to determine if a cylinder is loosing spark.

A crank sensor shouldn't cause this unless there is a problem with the toothed ring on the crankshaft that it looks at. Highly unlikely in my opinion. Also doubt there are any problems with pistons, rings etc. Not with 30 mpg!