I have cmiller's old 2009 red cobalt ss tc with 54k miles. Ive had it since 2014. Im the second owner. I had problems with misfires so much on this car. I did every plug and coil pack, fixed the problem for 2 weeks then smoke out of the exhaust. After that it was compression test. Came back 150 149 139 70. So it was new motor time. LDK bottom end LNF head with upgraded fuel lobe, new throttle body and exhaust mani, as well as new turbo and lines. Also new opel injectors. Eveything was in and running good, threw a MAF code. Found the wire was torn and soldered the wire back and code was gone. Drove it 30 miles and was misfiring when getting into boost at higher rpms. I know its the break in period and it shouldnt be beaten on but i just brought it to 4k to see if it would still misfire and yet again its still misfiring with a new motor! Only under WOT. Im very confused. I bought all new plugs even thoughy other ones were new and still nothing. Moved the coils around and still nothing. The coils are duralast but new from the older motor. I just don't know what next and don't want to keep pooring money into parts when they aren't solving the problem. New motor and turbo still misfiring the same way as before. Sounds like gunshots. I also checked hidden codes and it said cylinder 2 misfire, but as i said i did plugs didnt change a thing. Looking for some advice if someone has had this problem. No codes on car, drive and runs amazing only when WOT!

 

Get rid of the duralast and go with OEM's...

Are you using Ac Delco 41-108 spark plugs at .32?
Have you ever replaced the injector seals?

I would assume there's no valve gunk at such low miles.

Is your tune good and not shitty?

 

Is the car tuned? And is it running the same tune as before you swapped motors?

 

Its hp tuned from the old motor but it shouldnt be misfiring due to a tune. The only difference is the upgraded fuel cam, but could that cause a misifre? The seals are not replaced but there brand new injectors. The plugs as well are ac Delco but i didnt gap them personally just threw them in

 

Yes it is running the same tune as before but would that cause a misfire?

 

New opel injectors came pressed with new seals

 

Did you get new Opel Injectors for the new engine and are still running the old tune?

Because if you are that would mean your fuel trims are way the hell off. 14-15% off

You spent all this money and should be logging the car with HPTuners with the new build.

 

This. Even if you didn't have new injectors you'd need a new tune. Your tune was done for the old motor. The new motor is different. The reason that a factory file is "bad" is because it's forgiving enough to work with any motor that comes off the line. Once you tune it becomes specific to your engine. On top of that the LDK is different than the LNF (different compression ratio). Now you have new injectors to boot.

EDIT: just reread and saw you kept the LNF top end. Did you recondition the head when it was swapped?

 

I didnt keep the old head i bought a brand new one. I have been told it is the tune by my buddy im just making sure that it the problem before i spend 500 bucks on a new tune. I appreciate all the responses and i guess the nwxt step is a new tune. Thanks guys!

 

Well we can't tell you if it's the tune, as i said, if you changed to opel injectors then 100% you need a retune very badly.

You need to be logging the car yourself and learning to understand what the car is doing. It's the only way to be safe.

 

Opel injectors flow differently and now since you also have the different cam with the fuel lobe I'm guessing your way off. I would stay out of the throttle till you get a tune, and hope you haven't screwed anything up in the new motor. You can't swap injectors without checking what it's doing to your afr and fuel rail pressure.

 

This forum is screwed.

 

Op- boy did you start a war on SS gang with James and a couple others asking about a tune on SS gang. That's what happens over there way too often.

 

Didnt mean for it to be a whos who in the tuning world just trying to get a reliable tune for a good price. One guy quoted 650 to start and it would probably go up

 

Did the car have the Opel injectors on the previous tune?

If it didn't you need an updated tune, buy a copy of HPtuners standard (LNF has a wideband from the factory) you can get used copies all over the place. Contact 09Cobaltss1 on here he lives up near you and can get your tune setup correctly, while I don't know what he charges I'm sure it will not be more the $650 and he knows the LNF better than most performance shops around.

 

I think he did Eric, on Facebook, but said that John was too busy. He has been working crazy hours and I have had a hard time sometimes getting a hold of him. Plus he has a serious girlfriend. It was posted in SS gang and someone came in and lit James up in the post. Which turned into a lot a crap throwing by everyone. That page makes me laugh sometimes.

 

It did not have the cam nor the opel injectors before, i don't know who previously tuned it but i bought the car off cmiller. I know it needs a tune and i finally got a hold of John and were setting something up!

 

You will be in good hands with John. As I recall ZZP tuned Chris's car.

 

If Johns to busy OP PM me and I'll get you on a operating tune. I stay far far away from SS Gang for that reason right there.

I'm married so I have all the time in the world

 

I'm married too but my job takes my spare time. I try and stay off that site but there isn't much happening on here like there used to be. You aren't missing anything by not being on there, trust me.