Misfire and turbo issues: yet another thread
11-18-2015, 05:10 PM
#32
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Join Date: 11-03-2015
Location: williamson,georgia
Posts: 10
im going to add a little something ive been reading the posts the only way another sensor can cause this problem if it shares the same supply voltage or return you need a wiring diagram to see what sensors if any share a supply or return even though it is showing up at one sensor it could be another if it shares the same wire i also would look into injectors or spread open terminals in your sensor connectors
11-24-2015, 10:37 AM
#33
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Join Date: 08-07-2015
Location: NC
Posts: 62
im going to add a little something ive been reading the posts the only way another sensor can cause this problem if it shares the same supply voltage or return you need a wiring diagram to see what sensors if any share a supply or return even though it is showing up at one sensor it could be another if it shares the same wire i also would look into injectors or spread open terminals in your sensor connectors
I was also thinking that maybe the power supply to the coil might be the issue...
A friend of mine who used to work for GM suggested it might be the coils.. not just one but all getting "weak" and cylinder 4 having the most issues because how the intake works
All 4 coils would be like 100$
I'll try the GM top end cleaner in the next couple weeks (I need an oil change anyway), sprayed from the spark plug holes and intake. Also taking off and replacing the coils boots (I read somewhere that it solved a misfire issue :S). n the meantime looks for the wiring diagram
07-19-2016, 12:16 AM
#34
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Join Date: 08-07-2015
Location: NC
Posts: 62
It's been a while since my last update
Issue still not solved, just slightly evolved
Issue still not solved, just slightly evolved
- Tried sea foam first and also the GM top end cleaner, slightly better idle, but still misfire
- Installed ZZP High Output coils once first released, one failed after 3 days. Got the upgraded replacement over a month later. This in combination with NGK Iridium plugs LTR6IX-11, which are 1 step colder, gapped 0.030". Still same issue
- The car still won't misfire if I build PSI slowly even revving 4000+ rpm
- In the last 2 months the misfire occurs in this situation: going suddenly from cruising and a little gas to WOT, PSI would build and could misfire even at 8 PSI. So WOP will start popping, I back the pedal a little and find the sweet spot where it doesn't misfire and starts building pressure slowly again
- Found a leak in the upper IC. Ordered a new one from INJEN (for Cobalt), but when I was ready to install it, found out that it won't clear the OEM airbox. I'll be seling the INJEN IC pipe. After this I temporarily fixed the leak (will order upper and lower I guess)
- I have seen 21 and 23 PSI just twice for a fraction of a second. Otherwise 18-19 tops but non constant. This until 2 weeks ago when I run the car with the MAF disconnected (a friend who works on turbo Fords suggested this): On the interstate I could go WOT with no misfire (mostly) and constant PSI of 18-19 (with the IC temporary fix). But that's it.
- I also tried 0.0025" and 0.0035" plug gaps, same thing.
- A couple more top end and valve cleaners (CRC)
- I just ordered a new MAF and am waiting for it
07-19-2016, 12:48 AM
#35
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Join Date: 05-01-2014
Location: California
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Just read the whole thread, and from the first post it sounds like an injector problem. Swapped coils and plugs with no change, sounds like injectors. And now new coils and new plugs, still no change. Still seems like injectors. When you demand fuel quickly, it cannot comply.
I know it's a royal PITA, but you'll have to(links ahead) Remove the intake manifold to get to the injectors/ fuel rail. While you got the intake off, you can Shell blast the intake valves. Then you'll want to Install oil catch can(s) so the valves don't get gummed up again. (They may not be the problem now, but it's inevitable.)
I know it's a royal PITA, but you'll have to(links ahead) Remove the intake manifold to get to the injectors/ fuel rail. While you got the intake off, you can Shell blast the intake valves. Then you'll want to Install oil catch can(s) so the valves don't get gummed up again. (They may not be the problem now, but it's inevitable.)
07-19-2016, 01:52 AM
#36
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Join Date: 08-07-2015
Location: NC
Posts: 62
I'll need to plan ahead for that then... and half an hour ago found the intake removal thread too
RJ, by chance do you know the measures of the injector seal installation tools?
I can CAD it and 3D print it or machine it at work.
Thanks!
RJ, by chance do you know the measures of the injector seal installation tools?
I can CAD it and 3D print it or machine it at work.
Thanks!
07-19-2016, 10:19 AM
#38
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Join Date: 05-01-2014
Location: California
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Now that I think some more, you should check fuel pressure before you go to all this trouble. If your pressure is lower than it should be, it may be just barely enough for injectors 1, 2, and 3, but not quite enough for 4. I would think that if it were low, you would have gotten a code for low fuel rail pressure, but I don't know what the threshold is. I've gotten that code twice, but had no driveability issues, and it's gone away, so I didn't have to deal with it. Still, worth checking out.
Looks like you regularly drive dirt roads? That's a lot of dirt sitting in there, might want to look at your air filter again.
It sounds like you ran the seafoam before you replaced the spark plugs. If you ran the seafoam after, over your new plugs, though, you may want to think about replacing them again(at least #4). About 2 months after I seafoamed, I started getting misfire codes, and what fixed it was new plugs(again).
