I have an ecotec problem is it sensor or ignition?

FlintFredstone

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Backstory: I have a 2002 Cavalier with the 2.2 ecotec engine. A while back it lost power and was only running on two cylinders. I pretty much knew it was ignition related so I removed the coil-pack on top of the engine and removed the plugs for inspection. Two of the four plugs were worn so badly that they couldn't fire. There wasn't much left for the electrode to spark to, unless it was sparking to the top of the piston. I couldn't believe the car was even running with these plugs. With only $100 in my hand I purchased 4 new plugs and a new after market coil-pack to be on the safe side. I decided to use my old ICM. One of the new plugs was improperly gapped so in an attempt to get the gap in tolerance, I accidentally broke off the very tip of the electrode. I bent the cathode back in tolerance and "went with it". The car fired right up and ran perfect.... for about 2 months. Now I have a mystery.

The car runs fine while cruising above 1000 rpms but as soon as you come to a stop it starts missing and stumbling. It idles a bit low though and has an occasional miss. It gets worse if the cooling fan is on or the A/C. When the fan kicks on the car immediately stumbles and all the lights go dim as if the battery was low. I'm thinking that its only due to the 400-500 idle the car currently has, added with the random miss fire or stumble.

I just knew this problem was the ICM because that was the only thing I didn't replace and many places I searched online said this is the most common cause of miss fires and P300 codes. I bought a new "cheap" ICM that didn't fix my issue. Swapping my coil-pack out with the old one didn't change anything. Swapping out the ICM with the old one didn't change anything either. I thought it might be that one plug that I broke so I bought 4 more new plugs and installed them which still didn't change anything. This leads me to believe that the only thing my car needed was spark plugs in the first place, and maybe this is true. I have searched everywhere on many forums and elsewhere and found only 1 youtube video that shows a car like mine doing the exact same thing and they said it was the MAP sensor. I have one on order but I'm not thinking that is my problem either because:

Old coilpack with new ICM gives me best results. Still misses and stumbles but not as bad as other combinations.

New coilpack with old OR new ICM (don't matter) stumbles worse, misses more at idle

Old coilpack with old ICM is better but not as good as what the new ICM does.

The old parts are original equipment, the new parts are aftermarket and weird named.

If my MAP was bad, why all the variation with the different ignition components? Unless someone has a different idea I'm going to install the MAP and see what that does and if that don't work I may try to find O.E. Coils and ICM.

Some of the variation in the ignition components may be due to the plug boots not being shoved up against the coils completely. I'm hoping that it was just my error because if so it puts more burden on the MAP being the culprit.

https://www.youtube.com/watch?v=WOv2vXeKc4Q at the 0.33 mark you can see a little dip in the rpms. My car does this "dip" every 4 or 5 seconds.

I'm doubting it jumped time or my cat is clogged as I have experience with these issues on other vehicles. While searching for vacuum leaks nothing was discovered. Anything else thinking MAP sensor?
 

FlintFredstone

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I tackled them all.

1. Replaced spark plugs twice.
2. Bought new budget coils which didn't help or change anything.
3. o2 sensor? well it probably needs changed out but I don't think its that.
4. Fuel Injectors? I really haven't had to replace a fuel injector in any vehicle I have ever owned. I would say that an injector problem would cause a repeated misfire that you could predict. If 1 of my injectors is bad this would be my first in my 40 years of tinkering with old cars.
5. Burned valves will give a sustained sound or drive-ability issue along with a strange exhaust note. You can hear it in the exhaust if you know what you listen for and I do use the dollar bill trick but that isn't 100% reliable. My valves are fine.
6. Cat Converter? I can drive it all day at 3500 rpms with no loss of power, I probably need one but it seems to flow well still. It don't glow in the dark or smell funny. Its not my cat.
7. I don't have an egr.
8. Camshaft sensor? Maybe. This is number 2 on my parts list.
9. Defective computer? Nah lets hope not but might be possibility.

My personal opinion is either its my cheap ICM or my map sensor per that dude on youtube. This cheap ICM im currently running throws a engine light and "trac off" but runs better than using my new coilpack and old ICM.

This variation in performance by just swapping ignition components is strange tho. Again the boots may have not been properly installed on the coilpack in a couple of the first tests. The miss, more like a stumble is horrible at times. Could it be a combo of a bad ignition component along with the map? The map is on order and will be here monday. It could be the hose on the end of the sensor or the gasket may be creating a vacuum leak.

Going to install the map and see what that does. Its an inexpensive part, then if that don't work I'll try AC Delco control module.
 

zora

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So the only code is the P0300?
Did you use AC Delco plugs?
So no compression test?
 

FlintFredstone

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The first plugs was AC delco platnum... When I bought 4 more I got NGK. No change, the stumble was still there. No symptoms of low compression. Rings aren't worn to point of very much blowby, has very low oil consumption, and there isn't evidence of a blown gasket or burned valve so I have no reason to suspect the compression is low.

I don't think its actually a miss. Its a stumble as if you turn the key off for a split second, but anything above 1000rpms its smooth as silk. We will see monday as I suspect with my experience with gm vehicles and the current state of rot of many "useless" rubber hoses and plastic parts under the hood, that the MAP is leaking or bad. If its got a hose connected to it its probably dry rotted and cracked. If its "plugged" into the manifold to read the pressure then the gasket is bad or the part is failing... 175k miles before the first gremlin. Can't complain too much but it worries me that everywhere I look I see the dreaded missfire problem that is soooo hard to figure out. I'm running the car currently with an unknown engine code, because I'm going to try the MAP monday reguardless. Engine light and "trac off" is illuminated. This is not so when using the old ICM but the car stumbles considerably more. Thats why I think its either the MAP or a combination of MAP and a defective coilpack or ICM still because I don't really trust the the cheaper parts. I may have to start all over with AC delco parts.

We will see what the MAP replacement does.
 

FlintFredstone

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only code is p0300 when using the old ICM and it runs horrible.... with the new ICM it has thrown a code unchecked as yet by me (waiting on a map sensor to arrive).. it runs somewhat better with the new ICM but it also illuminates the "trac off" light as well. Im beginning to think i have a bad ICM along with a bad MAP or vac. leak. So I may be fighting two simultaneous problems.
 

zora

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I know you covered some of these already
Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked/leaking EGR valve / passages
Faulty camshaft position sensor
Defective computer
 

FlintFredstone

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Map came in today. I thought for sure it was the problem... but no.. its doing same thing... P0300 code stored, now no check engine light but "trac off" comes on.. stays a while then goes off only to return shortly after.

This miss or stumble at idle happens no matter if ac is on or off, but is usually worse when the cooling fan is on.

Now im thinking its the cheap ICM i got off amazon for $30 bucks because the old ICM runs with the same stumble and miss but much worse. The best combo so far is the Old coilpack with the new ICM.
The engine runs with the same problem no matter what coils or ICM I use just a matter of how bad it shows its self. Old ICM could be bad, The new cheap ICM may be bad as well, just not as bad as the old one.

Going to be a little while until I can afford an AC Delco part, few weeks at least.. Will keep everyone updated till then... if any other ideas come to mind, shoot them at me please.
 
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