My 03 cavalier has been saying it has a random miss fire for about a month now. Ive replaced the coil pack, icm, spark plugs, an injector that was faulty, and the fuel filter. What else could be causing it?


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

Can no one help me?


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

Did you replace the spark plug boots?

No they were still good. No corrosion or anything of that nature. Its gotten worse. I talked to a friend that works at a GM dealership and said that it might need a crank relearn. Im kinda leaning to that cuz it didnt start untill a trip up north in which the throttle stuck going down the high way and had to push the clutch to stop accelerating but when I did the RPMs shot to 6 then it came back down and everything was all good till I got up there and went to go somewhere the next day and when I started it, it was rumbling like it was camed from hell. Thinking it could possibly be the pump to.


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

I don't want to alarm you but mine was doing the same thing and it was the timing belt. I did over rev it once tough.

having the same problem, i pulled my first o2 sensor unplugged and it seemed to fix it for now, but i have over rev'd mine one twice and its about that time to get the timing done so i wonder if that might be it for me.



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Not alarming kinda thought that could be it to but kinda dismissed it cuz it has the chain instead of the belt. How hard is it to put it into time?


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

Trey Reed wrote:having the same problem, i pulled my first o2 sensor unplugged and it seemed to fix it for now, but i have over rev'd mine one twice and its about that time to get the timing done so i wonder if that might be it for me.

what code were you throwing?


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

SilvrSunfir wrote:I don't want to alarm you but mine was doing the same thing and it was the timing belt. I did over rev it once tough.

what timing belt?



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Rich Grayo Jr. wrote:

SilvrSunfir wrote:I don't want to alarm you but mine was doing the same thing and it was the timing belt. I did over rev it once tough.

what timing belt?

I think he is talking about this one:






-I drive my car to work-

See mines a chain. It did get a lil better after removing the first o2 sensor


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

robert lyons wrote:See mines a chain. It did get a lil better after removing the first o2 sensor

Is your timing chain still in good shape, just a thought but you may want to check that out too. If your timing is off that can cause a mis fire as well.

Idk ill look


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

P0300 and P0302, random missfire and cylinder #2 missifre, i have changed and done all i can to fix the problem besides a compression test or the timing.



2010 Lonestar Bash 2nd place J-Body Street Class
2011 texas heatwave 2nd place american compact street class

I assume the car has new filters too by the time the pressure regulator was replaced.

Some say replace injectors as part of a major tune up every 80 to 100 thousand miles.
The new O-rings sound good, but what if the injector's internal mechanical parts are worn out ?


I recently bought just one new injector under $70 and it runs good now as far as any misfires. I thought of just replacing the O-ring seals, but my idea was that seals and ohms are probably not the first thing that injectors wear out.

I also heard of batteries that act like they're good enough to start a car but they're just not quite good enough for the fuel injectors in operation, and checking for vacuum leaks

If it was run with a clogged exhaust for too long what kind of problems can that cause?

I'm sorry, there are now different threads about misfire, so I'm not sure if I posted this on the thread I had read.
If you already put a new injector in it then it doesn't apply unless the other injectors are also wore out inside.

All 4 injectors are new now. I havent changed the pressure regulator dnt even know what it looks like or where it is. Heres another symptom im having due to this miss fire. When you jusr ridding along at about 45 if you let off the pedal completely the car jerks bad untill you push the clutch or hit the gas but if you slowly let off the gas it doesnt do it.


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

If it's a gasoline motor the fuel pressure regulator might be part #9 in the picture at this link. It might not be exactly the diagram, because
that year they had natural gas motors too, but the pressure regulator does look like #9.
I think it also needs a vacuum line to make it work.

J FUEL INJECTOR RAIL (L61/2.2F)

SilvrSunfir wrote:I don't want to alarm you but mine was doing the same thing and it was the timing belt. I did over rev it once tough.

I meant chain when I said belt

Ok an update. Been driving it with the miss fire cuz I dnt have a choice. So went to the gas station and got something to drink and when I came back out to start it the car back fired and now wont start. Thinking it is the timing cuz the filter smells like exhaust and the guy working there said he saw smoke come out from under the hood but theres no leaks anywhere. Ideas????? Thanks


2.2 ecotec (stock internals) typhoon k&n in take 2 inch drop springs

If it is then you possibly just bent the valves and did some damage, you need to have it hooked up to a scope... Have a competent mechanic look into it.

You could try to turn the engine by hand. If you can't turn the crank pulley 2 complete turn the piston is hitting the valves. Are you capable of timing an engine?