Holger

Hey everyone. I really need help with my daughters Cavalier. It is misfiring and I'm running out of ideas.
First I wanna introduce myself a bit. I'm 41 and original from Germany, living since 8 years in Canada. I'm an Industrial Electrician and worked for the GM sister Opel in a Motor Production Plant. Worked there with my father who's an Industrial Mechanic and a Car Mechanic. I'm not saying, I'm Mr Know-it-all, but I grew up with cars and work on them for 25 years, but this Cavalier got me to the point where I just pull up my shoulders. No idea what's wrong.
I need your help.

It's a 2002 Cavalier 2.2l OHV with AC

My daughter came home with check engine light on and it wouldn't rev past 4000rpm. Hooked up OBD Reader and it showed P0300 Misfiring.
Then I checked connections of all sensor for moisture and corrosion. All Ok.
Then I was gonna check the spark plugs. First one came loose half way and then it got stuck. Went back in and out and in (just like tapping a thread). It came out, but thread was damaged. 2nd one broke off as well as 3rd one. Left the 4th one in. I thought F.........................k.

Took then the head off, drilled the plugs out, tapped bigger holes, put inserts in, secured them with high strength/high temp Locktite. New Headgasket, new plugs, new ignition cables. Found out, why they broke off. Chevy dealer sold me last year the wrong plugs. They were half inch too long. The plug thread was actually sticking into the cylinder and got seized up. There was just a hair room between the plug and the piston.
While I had the head sitting on the work bench, I put on every valve seat gasoline and let it sit for a while to see if valves are leaking. All Ok.
After motor was put back together, I turned the key and still misfiring without and error codes, just not going past 4000rpm and idling a tiny bit rough.

Checked then injectors for resistance. Ok. Fuel filter got changed last year.

Checked then Ignition with a testing light between every plug and cable to see if coil works. Ok.

Checked sensors again. Pulled off, for ex., the Throttle position sensor while running. Motor almost stalled. Tells me, Sensor works. Did that with all of them.

Computer was last thing to check. It has a blue and a black quick connect. Took both apart. The pins of the black one were in a really bad shape. Tried to clean them, put it back together and still misfiring.
Noticed, while motor is running, when I pushed on the black one with my hand and moved it right and left that the motor ran. I thought, Yessssssssss.

Went to the salvage yard and got a new motor harness which is in a really good shape. Installed it and it still misfires. Tried that thing again with my hand on the black plug and didn't change anything. New plug sits tight.

Went back to salvage yard to get a new computer. Cavalier didn't start at all.
Brought it back and got another one and a MAP Sensor. Still doesn't start. It runs with old computer. What are the chances you get 2 Computers in a row which don't work? Or is there a trick to synch a different computer to the car?

Ran motor without gas cap to see if ventilation works.
Checked all under pressure hoses for leaks.
Sprayed break cleaner around the air intake manifold to see if there is a leak. Nothing. Tried propane gas as well, because it"s thinner.

All I have left for troubleshooting is bad gas or water in the gas. Maybe somebody put something in her tank at night. But with water in the gas will the motor misfire everytime at exactly 4000rpm?
Maybe plugged muffler? Mouse build a nest in it?

My neighbour is a car mechanic at a Toyota Dealership. I had him look at it. I brought a professional OBD reader. All sensors work fine. Oxygen, Map, Throttle, Knock Fuel Trim etc. No error codes.

I have no idea what to check next.

And getting rid of it is not an option. My daughter is a student and it's her first car and she loves it. It even has a name.Linda.
And I pounded too much money it it. Besides the almost $400 I put in to fix the cylinder head, I did all the breaks, front hubs, muffler, Remote Starter and she has brand new winter tires on it.

Holger

Disconnected this afternoon the exhaust at the header to make sure the catalytic converter is not plugged. Still misfiring.

iBlackSunday

Is it misfiring only in drive or reverse or even in neutral/park? I had an issue where a wire was smashed in between my trans mount and trans where it was shorting the cable which wouldn't allow the RPM's to go above 4000 when the mount was flexed in drive.

Holger

No, it misfires all the time. While driving, in Neutral and park. It misfires also when it's cold or warmed up, which means it can't be a valve. Cables are Ok, because I got a new harness.
I skyped with my dad on the weekend and he said, it might be either the Knock, Crank shaft or Cam shaft Sensor. Even though I don't get an error code for the sensors due to that it is an P0300 code which means it's misfiring on 2 or more cylinders. After clearing the P0300 it didn't come on anymore, but still misfires. It might come on when I drive it for a while.

That's why I checked these sensors. The problem was, that the Crankshaft Sensor was one solid piece with the motor block and it broke off. Cavalier has 250000km. Sooooooo, I got it out but the tip fell into the oil pan with was some sort of small cylinder made of Aluminum or tin. I drained the oil hoping it slides in front of the drainage hole, but didn't.

Now I'm not sure if I should just leave it in the oil pan, because it is too big to fit through the screen of the oil pump infeed pipe. Taking the oil pan off is a pain in the b...Motormount has to go, as well as the Starter, A/C Compressor, Exhaust and Flywheel inspection cover. Ooooooh boy.

If it wasn't the Crankshaft Sensor, there is the Camshaft and Knocksensor left. This week I might take the motor cover off again and crank the motor by hand and see how the rockers open the valves to check if timing is right. The chain might jumped over a tooth.

Or I might ask at the salvage yard how much they want for a motor with 100k less on the clock and switch it instead of buying a **** ton of sensors and investing time in taking the oil pan off and in the end it is the timing which isn't right. By the looks of it, I have to take the motor out anyways to get to the chain. Not sure if there is enough room

tech2

i agree with you dad about a cam or crank sensor. this is the 2200 and not the 2.2 ecotec correct?

when the signal goes bad it can seem like its hitting the rev limiter

kevinkpk

If you've got a burnt valve, it will miss fire hot or cold.

Holger

Yes, it is the 2.2 OHV, not the Ecotech.
Installed the Camshaft Sensor today and it still misfires. I pulled the plug off while it was running and it stalled right away.
Then I pulled the camshaft sensor and nothing changed. Checked the signal while running. 3 wires. 12VDC, Ground and Signal. The signal is 0.9V. Not sure if this correct. 13.45V are going in and 0.9V as a pulse is returning to the computer. Gotta check on that.

@kevinkpk
When I had the head off, I put gasoline onto the valves and let it sit for a while to see if they leak and they didn't. Not sure if this tells me that they are 100% closing/Ok.

If I find out that the 0.9V Pulse from the Camshaft is correct, I might see how much the salvage yard wants for a motor. They have a bunch of Cavaliers. It's now the 3rd week I'm working on it. Getting sick of it.

Holger

Changed today camshaft sensor, knock sensor and ignition coil. Still misfires.
So, there's only 3 things left:
1. Burned valve
2. No compression
3. Timing chain jumped over
Noticed also that both steering ball joints are done and lots of heavy rust on the rear frame close to where the shocks sit.
I think it's time to say goodbye.

tech2

a compression test will tell you what you need to know. timing chains tensioners were bad for these motors but you usually hear the chain hitting the timing cover.

Holger

I got a compression tester here, but never checked, because I re-taped 2 spark plug threads and I oversized 2 and put inserts in. Scared to take them out. But I guess I have no other option.
The chain is quiet, when the motor runs.
But the funny thing is, that the motor ran for a few seconds when I had my hand on the computer plug and moved it slightly. Misfiring was gone. That's why I got a new harness and it didn't work. Won't start at all with 2 new computers, just with the old one. And we had last year some trouble, that the cavalier didn't start. Got a new computer and it worked, but keep the old one because I can't throw things out. Somehow that old computer works. So I have 4 computers in total with the exact same numbers. 2 old ones work, 2 new ones not.

Or did moving the plug (with really bad corroded pins) change somehow the timing, the interaction of the sensors that it ran? That's why I focused on the electric and not compression or timing chain