------------------------SCENARIO-------------------------
Alright, so Ive got a 2004 Cavalier.
2006 Cobalt SS/SC supercharger components installed.
Stage2 42lb injectors.
For numerous reasons over the past few weeks Ive had the injectors off quite a few times to troubleshoot a leak.
The o-rings were the culprits and eventually I got the injector to stop leaking all over the manifold.
Then the FPR started leaking since the injector allowed the pressure to back up (it was just old and leaked through the round diaphram spot).
Replaced the FPR and no more fuel leaks. All good.

However, somewhere in that process I cant remember exactly when, but the car started misfiring randomly at constant speeds. Over the course of it misfiring oddly and even a few times REALLY driving rough when getting on it, I had enough and thats when I did the fixes above.
------------------------ISSUE--------------------------------
After getting the injector and FPR fixed, I was test driving it and it started to REALLY misfire badly. It was still idling rough even with the leaks fixed, but if i tried to drive it would simply feel like it was just not getting fuel.
CEL kept coming on with a few different codes, one was the P0301 cylinder1 misfire. I found out after removing my intake manifold, the cork gasket that I had on there from the OEM Phenolic spacer was never removed and it was just that between the manifold and head. I guess the leaking fuel had eat away at it and the gasket was literally missing all around cylinder 1. Spraying carb cleaner in there would near kill it.
Took it all apart, bought an LSJ IM gasket and even used some spray copper gasket maker on it just to be safe.
The P0301 code is gone, no more vacuum leak from the manifold.

----------------------TROUBLESHOOTING----------------
However the misfire still remains. It is throwing only a P0201 now. The code indicates: "Generic : Injector Circuit / Open - Cylinder 1"
Ive swapped injectors and its still calling for the CEL on cylinder 1.
Ive tested the resistance on cylinder 1 injector, engine off, accessory off, car off for about 2 hours (engine barely warm to the touch) and it was 14.6ohms. I heard the stage2 were high impedance and were 16-18ohms or something warm I believe.
Ive tested the voltage at the injector harness, accessory on, read 9.6v.
I think its a fuel injector harness issue. Not sure how to test it. It doesnt appear to have any breaks in the wiring, but I suppose I could remove the pins from the clip and inspect those.

This is where Im at now. Terrible misfire, P0201, injector seems fine, wiring is most likely the culprit.
Thoughts?
Also, heres a link for the basic OBDII codes and the P0201 specifically: http://www.obd-codes.com/p0201


Edited 1 time(s). Last edited Wednesday, November 07, 2012 7:15 PM

04 Cav. 2dr. 5spd. My DD. 'Nuff said.

I wanna say to get a wiring diagram of the injector harness and do a continuity test for injector one. Doing so by back probing the connectors with T-pins or small paper clips.


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Yea do a continuity test first, and if you pass that, I'd grab a set of noid lights and test with those

Im going to tear down to the injectors again and do a resistance test on them all just to verify. maybe go pick up a fuel injector noid light if the local parts store carries the kits.

*Edit: yeah Evil I had the page open and posted before I saw your response. But I just read up on the noid light test to determine if the circuit is the issue...


Edited 1 time(s). Last edited Wednesday, November 07, 2012 10:38 PM

04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Quote:

Ive tested the voltage at the injector harness, accessory on, read 9.6v.

If you tested that across that injector plug, you shouldn't be. Hot should be at the injector at all times. The ECU switches the ground side to run the injector. Having voltage is a sign of a short.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

I had this code. My car sounded like a machine gun. Turns out the driver on the ECU was bad. I had to get a new ECU. Its either the ECU or wiring in your case. Test it yourself or take it to a mechanic. Shouldn't cost more than $120 for them to troubleshoot.

So the drivers are individual per injector right? can just one driver go bad on the ECU for a specific cylinder? what causes a driver to go bad?

Ill have to recheck SHOoff, but I believe the injector plug was getting 9.6V hot...so that means Id have to trace one of the wires to a possible short somewhere? And thats not easy..since the harness is factory wrapped and Id have to remove a bunch of stuff to trace the routing of it (plug under the blower by the alternator for instance)


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Yep one can just go bad for me it was injector number 3. Do you have a wiring diagram? I have the gm service manual I can get you the pic on the ECU to test.

Yeah I'd be interested in finding out how to test the ECU itself. I do have it relocated into the cabin and its sideways, wedged behind the console/cupbolder area. But its never had a problem.

Is it just a random failure or what? Cause it seems it just happened after messing with injectors..which is why Im more leaning towards a physical issue like the connector wiring or injector itself...

I guess to properly determine if thats it, Id need an 04 ECU, 5speed, and have it reflashed with my current tune.


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Mine was randomly acting up when I would start it and it would go away. When I relocated my ECU to the cabin it finally crapped out 100%. If you have a stock ECU you should be able to let it idle on that and tell if the injector is pulsing correctly. I'll dig up that pin number when I get home.

Sounds like a short in the injector harness to me as well. More than likely the injector harness will have to be replaced.




Currently #4 in Ecotec Forced Induction horsepower ratings. 505.8 WHP 414WTQ!!!
Currently 3rd quickest Ecotec on the .org - 10.949 @ 131.50 MPH!!!

OK Fuel Injector 2 Control is PIN Number 51, The wire is BLK



I can email you the troubleshooting steps for the code as well. PM me your email if you want it.

sorry its fuel injector driver 1 PIN 51 the wire is black

awesome.
yes I saw the black wire on the connector. There was i believe a solid orange one (faded) and a black one. The orange one went across the fuel rail and the black one went down to the connector that clips onto the harness connection under the blower, right next to the alternator. I think its a 5 pin connector.

I dont have a spare ECU...plus would my engine even idle or stay running on a stock computer with my mods?

After work Im going to test all 4 injectors for resistance and make sure they are good.
Then Ill recheck the voltage to the connector, and like SHOoff said, if it has voltage with the car on accessory then its shorted...Id much rather just replace a damn injector than have to undo my wiring harness and fix a short unless its in an easy spot (-_-)

my email is fastcar94z@hotmail.com...Ill shoot ya a PM too, thanks!
I am also thinking about picking up a noid light kit as well..


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

It idles if you disconnect the TMAP. Sent you some xps files with the schematics. ignore the oxps ones unless you have windows8

nah, still running on Windows 7 Ultimate 64bit, hasnt failed me yet

and thanks, Ill check them out when I get home. Im just not really wanting to get into the wiring but its looking like i may have to.

Just sucks this all happened at once...I am on the verge of getting my car finally tuned decent with the current setup after 8 months of running like poop (from a performance stand point) and then shortly here will be doing cams, springs, and meth.


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

If it makes you feel better im battling a ghost p0300 code.

Yeah I was getting a random rich code and random start ups I'd get a p0203 for months and my injector driver turned out to be slowly failing on me. Hope u get it figured out. Electrical issue suck!

Philly, I ended up removing everything down to the head a few times and reinstalling. I bought a brand new LSJ manifold gasket and sprayed both sides with spray on copper gasket maker. it fixed the P0301 code I was getting (general misfire) but ive obviously got multiple issues.

But I am off tomorrow to go gofling on base, then Ill have all night Friday, all weekend, and Im off Monday. So if I cant figure it out by Tuesday, I dont deserve to have my car, Ill sell it, and the highest bidder wins


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Philly D wrote:If it makes you feel better im battling a ghost p0300 code.

Also battling a random misfire. I only get it on cold start and only every once in awhile. Now it hasn't happened for at least a month

OP, let us know what ends up being the problem. I have a strong feeling you have a short somewhere in that harness.


"In Oldskool we trust"

I too have a small random misfire at idle.....

Mine only seems to come on a few minutes after I start driving, and it sets the code around 2800 rpm. No noticeable miss or anything the light just comes on.

YellowCav, you may be right. But I have decided not to troubleshoot tonight. I am beat from golfing all day (yes, I golfed from 1000 to 630 lol). I am chilling with some cold beers right now and that is my level effort to do much

misfires are a common issue. Ive read up on a lot and its best to check injectors resistance levels, spark plugs for odd chemical build ups or carbon trails, vacuum leaks, or anything really that is quick to test. Im just not looking forward to having to replace (and retune) my ECU if its a faulty driver or a completely wiring harness inspection. Id rather drop the $$ on new injectors.


04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Well I think i found the culprit.
Im going to test my theory here shortly.
After removing the fuel rail, exposing the injectors and the wiring harness, I narrowed down tot he two wires on the fuel injector connection on cylinder 1.
The orange/pinkish wire was fine.
The black wire (correllates with #51 pin on the ECU) was bent bad in a certain spot near the connector. I believe I broke the connection removing my fuel rail so many times troubleshooting the P0301 misfire where my intake manifold gasket was broken.
I cut the wire and sure enough its broken inside. Im going to splice in a new section of wire tonight hopefully if i have that wire gauge, but I think that should fix it.










04 Cav. 2dr. 5spd. My DD. 'Nuff said.

Victory is mine!
She runs great now that Ive fixed both the P0301 and P0201 codes!

Now to figure out why i only get 8psi...and to get a tune for being super rich at anything other than normal throttle.

But she's alive..woohoo!


04 Cav. 2dr. 5spd. My DD. 'Nuff said.