Just got a 00 Cavalier, and within 3 days have replaced the starter, fuel pump, the #4 injector, new plugs and wires. Now, after ALL that, today when pulling into my street, the check engine light as well as the trac off lights come on and the car has a noticeable loss of power and runs and idles rough, but oddly, does not stall. o2 sensor? im at the end of my rope after putting over $1000 into this car in less than a week and im still having issues.

I also noticed upon further inspection, that the fuse in the interior fuse box for the fuel pump was a 30amp fuse and not a 15 as recomended....nevermind. didnt work. Also replaced the relay under the hood before the new fuel pump was installed.
Car ran fine, actually great after all that work as of this afternoon.

got codes read, and are as follows P0204 and P0304. Replaced plugs and wires and still have the same condition. Im lost here. Totally.
Took car back to garage that replaced the injector..."we may have screwed up somewhere, or it could be your computer is shot". It gets better and better. Damn!

The misfire is in cylinder 4 and no one can seem to solve this riddle. After all the money spent, the car runs like a go kart that was just pulled out of the river.

Thanks for any suggestions in advance.

also, i should add, battery is newer, coil packs are good, all fluids good to fair

Well, with the key on, the gray wire at the injectors should get powered. I would put a noid light on the plug for that injectors and start it. If the noid light flashes, circuit and pcm are good. If you have power at the gray, but still problems, then check continuity of the blue/black wire from the injectors to pcm. No continuity is broken wire, if you have continuity, you need a pcm. If you don't have power at the gray wire, then look for the broken wire, cuz all injectors get power from the same wire, and then it splices off into the 4 injectors. Good luck!

Thanks for your help Dave, now i'm just gonna hope and pray its NOT the PCM, i'd be royally screwed.

Why? Just get a jy one and your set if its the pcm. They should be cheap from harrys.

I'll without a doubt look into that in the morning....but wouldnt i have to get it flashed at a dealer? and how costly could that be?

Sorry if my questions sound dumb, I have never dealt with a situation like this before.

Just find a car that has your engine, trans, and options, like cruise control, and such. I'm a Chevy tech. If you can't find a good match at a junk yard, my dealership charges about 50 bucks for programming. Not expensive. I would assume most are the same.

Yeah, you are right dude! I just called a local dealer and they just quoted me about the same. Ok I can breathe a bit easier today knowing that this will not cost me a fortune either way. Thanks Dave, total life saver info!

Anytime!

Another update...replaced the coil packs, nada...same issues.

I didnt have this issue until they replaced the fuel pump. Upon buying the car, I was told by the previous owner that the fuel pump was indeed, in the process of failing(blowing fuses), but accepted that fact as a condition of sale, and got what i thought at the time was a deal, esp considering the condition of the car, which is excellent(considering it has 130k miles on it, and figured a new fuel pump would be more cost effective instead of a new engine in the Monte Carlo I had)! The were no issues with any injectors until i took it to the shop and they told me i needed a new #4 injector as well as a fuel pump. 2 1/2 days after they replaced it is when all these issues began...When i bought the car, it ran great, but would blow the fuel pump fuse daily, but no check engine trac off lights or codes.

BTW, just for @!#$s and giggles, i replaced the 2 coil packs, again, nothing changed.

so, just to run it all down,
New fuel pump
New #4 injector
New plugs and wires
New coil packs
Plug wires confirmed not mixed up
Confirmed compression in cylinder 4
Battery is less than 6 months old(checked and is good)

Still throwing out P0204 code.


I guess im running out of things to replace here, but it's going back to the shop this Thursday. I really hope this ends soon, one way or another.

I don't wanna give up on the car, but I'm reaching that point.

Another question as well....is the car safe to drive as it is right now? I work nights, 7-3am, and because of this i cannot afford to miss.

Did you check the stuff I told you to?

that was a new fuel pump
and filter, right?

I also cleaned my fuel system twice with regular sea foam when I replaced one injector.

I wont be able to check those things till thursday. I have limited access to tools and im totally broke! This Cavalier has turned into a literal money pit for me.

A buddy of mine also seems to think that wiring is the issue(obvious from the code), but also thinks it could be as simple as a dirty harness that plugs into the injector, or they didnt install a new O-ring...those two would be best case for me, but doubtful. I'm never that lucky lol

yes, new fuel pump and filter...

I don't think its the o-ring personally. And the things I had you check will check wiring as well as module.

what has me baffled is AFTER the new injector and fuel pump were put in, the car ran great. How common would it be that a wiring or PCM issue would correct itself for almost 3 days, but then fail after a new injector was installed? I value your opinion here Dave, as you know what you are talking about....im just chasing a dragon lol

Another thing i do wanna mention too, is that there is NO black or white smoke coming out of exhaust, and there is no long crank time to start engine. it fires right up. I guess that would mean it's not running rich, but lean?

Im just trying to assemble as much info about this as i can so i can present all this to the shop tomorrow, so they dont have to go on yet another wild goose chase and narrow it down.

Change the ICM. It interfaces with the injectors, crank sensor, PCM, and part of the ABS.




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

-MD- Enforcer wrote:Change the ICM. It interfaces with the injectors, crank sensor, PCM, and part of the ABS.

Schematics only show common power and pcm grounding. I would rather he test what I told him to before he replaces stuff...already threw a lot of parts at it. Throwing parts gets unnecessarily expensive. Not trying to argue, just my opinion.

When my ICM was bad it would mess with my Trac off and completely mess with the crank position signal to the PCM. This was on a 99 auto Z24.







PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

I think i may have found the problem....but im not certain. If this is wiring to/from the injector, this would explain the P0204 code. How the hell did i miss this???

I'm a n00b, but I think i can do this myself, but would appreicate any help. I'd assume the first step would be to disconnect battery.....

I want to be totally safe and not fry myself here...should i also remove fuse(s) and relay?