1999 Chevy Cavalier - Intermittent Problem


#1

I recently bought a 1999 Chevy Cavalier with around 60,000 miles on it thinking it would be one great and reliable little commuter car.

It ran beautifully for the first week I had it, then one day it started idling rough at red lights, then stalled as I tried to park it.

Since then, it has been aggravating me off and on. It is usually worse in the mornings and almost always improves with further driving, leading me to think this might be a moisture issue…but just when I figure something out, it misbehaves on a dry afternoon.

Sometimes the check engine light comes on when this happens…had that read and it said “random misfire” - really? How helpful.

The mechanic recommended a new fuel filter which I tried to no avail.

Sometimes at highway speeds you can feel the engine missing/jumping also.

Bottom line, there is almost no consistency to this problem, and sometimes it will run great for days at a time.

Any ideas or suggestions?


#2

I understand. The engine computer isn’t telling EXACTLY what is wrong. A knowledgeable mechanic, with an engine computer scan tool, can narrow the number of possibilities. To see some of the difficulties with diagnosing the problem, go to www.autotap.com. Scroll down and click on Engine Stalls, Misfire Code & Cylinder Missfire. Then, scroll down to Problem #7 …Missfire Code.


#3

There may be a coil pack failing causing an intermittent spark (random misfire).

Engine misfiring/rough-running can be caused by a number of things.

Here are a few: Faulty ignition system, dirty throttle body, cylinder compression issues, faulty spark plug wires and/or plugs (perhaps incorrectly gapped.

Vacuum leaks at the throttle body, intake manifold or vacuum hoses or emissions faults are a few more.

Was this vehicle ‘tuned up’ before you bought it? (Bear in mind that tune ups on todays vehicles are somewhat different than years gone by)


#4

It was not to my knowledge tuned up before I got it. My mechanic didn’t seem to think that the plugs or wires needed changing yet (based on the fact that they’re platinum plugs and should be good for 100,000 mi). I guess the worst part of this problem is that it is not consistent enough to be able to demonstrate it for the mechanic.
Is there a simple way to test the coil pack? Or is it something that would routinely need to be changed anyway?


#5

You’re only getting one code?

OEM plug wires usually will last the life of the vehicle. (Usually, not always)

Plugs can foul (Regardless of make or type) You’ve only got four so why not eliminate that possibility?

Are platinum plugs recommended for that engine? OEM? I always stick with OEM plugs when servicing my two vehicles and never seem to have trouble. (both GMs)

Inconsistent faults are any techs nightmare.

Coil packs are not a routine service. These are normally checked and/or changed (if proven faulty) when there is a misfire.
Coil packs can be checked with the engine running and a meter hooked up to check for a steady voltage.

I’m not a tech so someone like Tester or OK4450 (plus a few other regulars with the knowledge) can give you a more precise explanation.


#6

Right, the same code was stored 4 times.
I’m assuming that those plugs originally came with the car. I should probably go ahead and change them…But wouldn’t bad plugs cause a more consistent problem?
Thanks for your advice.


#7

I appreciate the info!