SkyRay's Extended Track Goblin #314 - 09 SS/TC

SkyRay

SkyRay

Active Member
Thanks for the responses! After my post last night, I also googled the two error codes and "Cobalt." I hit on a post on a Cobalt SS forum where they had a similar problem. They never confirmed the fix, but speculated it was the ECM. However, they also said they could clear the codes and the car would run again for a while. So I tried that and, to my surprise, it ran. Not great, but it ran. That made it possible for me to jiggle wires, per your recommendations, and I found an area where, when I touched the engine wire harness, the engine would die. I dug around there and found that, as you suggested, one of the engine ground wires was loose. So I got it reconnected and now it runs without dying when I move the wire harness.

However, it is still running rough. Now I'm getting the following errors:
P0204 Cylinder 4 Injector "A" Circuit
P0300 Random/Multiple Cylinder Misfire Detected
P0304 Cylinder 4 Misfire Detected

So, tomorrow I'll continue to troubleshoot the Cylinder 4 issue. If you have any additional suggestions, please let me know. Thanks for all of your help,
 
Rttoys

Rttoys

Goblin Guru
Nice. Now you are narrowing it down. Not sure on the #4 injector problem. Gotta kind of start over. Could be as simple as a coil or injector. Don’t discount wiring though.
 
SkyRay

SkyRay

Active Member
Alright, after a week I was finally able to spend a little time troubleshooting today. Very unfortunate timing that this has happened during the Christmas party/concert and poor weather season.

I started out looking for loose/intermittent connections. I found that, when I would clear the error codes, the car would run smoothly for around a minute, then the P0204 code would come back and it would run rough. Moving a harness around or jiggling a connector didn't seem to make it worse or better.

For my next step I used the troubleshooting guide provided by Gtstorey in post #143 (thanks so much!). I didn't have a troubleshooting light, but have a DMM so used that instead. Step 3 on Circuit/System Testing is looking for the signal at the ECM side of the X162 connector. I found that under cranking I had a good signal for injectors 1-3, but there was no signal for injector 4. Hmmm... We've checked the engine harness for continuity between the ECM and the X162 connector, so seems like that signal may have a problem coming out of the ECM.

So at this point I'm leaning toward ordering a new ECM. Looks like it would be about $700 to get one from Flagship One. Any additional thoughts? Thanks again for your thoughts and advice.
 
Ross

Ross

Goblin Guru
LKQ had LSJ P12 ECU for a couple hundred. Has prices gone sky high? $700 seems steep, but maybe times have changed since covid.
 
SkyRay

SkyRay

Active Member
The shop I had it at quoted me $1400 for a replacement, which they said they had to get through a dealer and get it programmed with the original load.
When I first reached out to Flagship One they said ~$350. When I gave them the VIN they said it would be $700, and that would be programmed with the original load.
From looking online, it appears that an unprogrammed one can be purchased for $350, but then I'd have to figure out how to get it loaded with the right settings. Then I would still need to get it tuned and have the codes tailored.
I'll reach out to Adam to see if he's got the most recent load from when I took it down in June. Perhaps I can get the new unit for $350 and have DF reprogram it for me?
 
G

Gtstorey

Goblin Guru
Probably can’t be done with HP Tuners although it’s a little confusing on what exactly can be written on the ECM. If it’s a brand new ECM it will have to be programmed through the ACDelco subscription service. Maybe a used ECM could have the VIN changed and be made to work with HPT but typically when asked on the HPT forum the answer is that it has to be programmed first outside of HPT.
 
SkyRay

SkyRay

Active Member
Gtstorey said:
Probably can’t be done with HP Tuners although it’s a little confusing on what exactly can be written on the ECM. If it’s a brand new ECM it will have to be programmed through the ACDelco subscription service. Maybe a used ECM could have the VIN changed and be made to work with HPT but typically when asked on the HPT forum the answer is that it has to be programmed first outside of HPT.
Click to expand...
Thanks for the intel. I'll call the local dealer this morning to see if they would sell an ECM, programmed, to an individual. Or see if they would program one bought online. I also need to re-price the ZZP option since Flagship One doubled their price when they accounted for it being an SS.
 
G

Gtstorey

Goblin Guru
The interface and subscription to load the new ECM isn't that costly but I have heard that it is annoying to use with a lot of crashes and issues and that it can take several hours to be successful (one of the reasons it's expensive to get someone to do it.) No first hand experience though.

I still think it's strange that you got one injector to work by fixing a bad connection but not the other. I guess the bad ground may have caused one of the drivers to overheat. Have you back probed the wiring at the ECM while connected to confirm no power to the injector?
 
Goblinfanclub1234

Goblinfanclub1234

Well-Known Member
ZZP took care of me with this one. some people on the cobalt forums think it could be caused by a bad injector also. maybe a local place can test your injectors on the bench. they recommend switching injector #1 and #4 to see if the problem moves to cylinder 1. cheers.

zzperformance.com

ZZP LNF Turbo PCM

The ZZP LNF turbo PCM brings the performance of your turbocharged Cobalt to the level that the factory should have released it with.
zzperformance.com zzperformance.com
 
SkyRay

SkyRay

Active Member
Thanks for the continued help and suggestions. Unfortunately I don't feel like I'm any closer to getting this solved. To summarize:

- Initial Problem: Car died while driving down the street. Wouldn't start again, had to tow home and to a shop.
- Shop said there were 2 error codes, Injector 2 and Injector 4. They probed for a signal at the connector between the engine wire harness and the injector wire harness and said there wasn't a signal being received. We probed between the ECM connector and the engine wire harness connector to the injector wire harness and couldn't find any opens. Shop recommended replacing ECM for $1400 and would take 2 days. I decided to bring the car home because I can replace the ECM for less.
- Forum recommended checking wiring and grounds. I found the ground between the engine wire harness and the block to be loose. Upon tightening, the car would start and run but continued to have a misfire code but only on injector 4. I confirmed using the GTStorey's procedures that I wasn't getting a signal to injector 4.
- Per GTStorey's recommendation tried to back probe the ECM connector but found that either my probes aren't long enough or the connector is sealed, so back probing wasn't successful. Didn't want to try to pierce the wire in the engine wire harness.
- I called ZZP about getting an ECM, the guy I talked to said the ECM is very robust and he can't imagine it is dead, but perhaps I could have used the wrong spark plugs ("don't use NGK, only Delco"). I was pretty sure I had used Delco and pulled one to confirm they are the recommended Delco plugs.
- I tried running the car. Now have Injector 1 and 2 errors.
- I decided to take all the grounds apart and hit with wire brush, reapply dielectric grease, and tighten. Completed this.
- I used GTStorey's procedures again this time had positive signal to all 4 injectors at the engine wire harness connector.
- I tried running the car, Now have injector 2 error.

So at this point I'm at a loss... Injectors 2&4, then 4, then 1&2, now 2. Hardly seems like a "hard" failure. I've fixed the grounds, can't find an issue in the engine harness. Anyone ever have connectivity issues between the ECM and the engine wire harness? When I took that connection apart at the start of the story, we noticed dielectric grease on the pins. I'm wondering if the prior owner had some intermittent connections and used the grease to make them more consistent. Other suggestions?
 
SkyRay

SkyRay

Active Member
Goblinfanclub1234 said:
ZZP took care of me with this one. some people on the cobalt forums think it could be caused by a bad injector also. maybe a local place can test your injectors on the bench. they recommend switching injector #1 and #4 to see if the problem moves to cylinder 1. cheers.

zzperformance.com

ZZP LNF Turbo PCM

The ZZP LNF turbo PCM brings the performance of your turbocharged Cobalt to the level that the factory should have released it with.
zzperformance.com zzperformance.com
Click to expand...
Thanks for the responses and ZZP Info. Some thoughts:
- At ZZP it looked like there is a $350 adder for "Custom LNF swap" that would push the price up to $900+, which I was hoping to avoid.
- I thought about pulling the injectors, but since it seems to jump around from injector to injector on its own I didn't want the hassle of pulling the intercooler and intake manifold to get to the injectors. In hindsight I wish I had replaced them with the clutch, timing chain, and water pump before I installed the engine.

Thanks!
 
SmsDetroit

SmsDetroit

Goblin Guru
SkyRay said:
Thanks for the responses and ZZP Info. Some thoughts:
- At ZZP it looked like there is a $350 adder for "Custom LNF swap" that would push the price up to $900+, which I was hoping to avoid.
- I thought about pulling the injectors, but since it seems to jump around from injector to injector on its own I didn't want the hassle of pulling the intercooler and intake manifold to get to the injectors. In hindsight I wish I had replaced them with the clutch, timing chain, and water pump before I installed the engine.

Thanks!
Click to expand...
They told me the same thing about the LNF swap. I just gave them my cobalt vin and had them program it to that. I avoided the extra charge. I may have to modify the tune a bit but it saved a ton of money
 
G

Gtstorey

Goblin Guru
A few points.
You can use a piece of mig wire or sewing pins/needles to back probe the connectors. But don't be afraid to pierce the wires, it's just one of those things that you sometimes have to do tp trouble shoot. People that do a lot of electrical trouble shooting use these.

Dielectric grease is non conductive, it won't improve the electrical connection. But someone else may have thought it did and added it hoping to help a problem.

I wouldn't expect a dead plug to cause an injector code. I'll find out my next drive if the NGks can cause a problem since I stuck some in recently. I really don't expect a problem.

If this was mine, my wring harness would look like a pin cushion right now so I could check things from the ECM to the injector to see where the problem is without disturbing the harness. Or I would just rewire from the ECM straight to the injectors (although that might be difficult accessing the injector wiring).
 
Goblinfanclub1234

Goblinfanclub1234

Well-Known Member
I also gave ZZP my vin for the cobalt and all was good - that swap charge was not included.

this might be a dumb suggestion but can you double check to make sure all of the bolts that hold the fuse box top down are cranked down tight?
 
G

Gtstorey

Goblin Guru
Goblinfanclub1234 said:
this might be a dumb suggestion but can you double check to make sure all of the bolts that hold the fuse box top down are cranked down tight?
Click to expand...
I don't think it's very likely that the fusebox connection would affect a single injector at a time, but I guess it's possible if the interruption is very intermittent/short.
 
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