I bought the car and when I got it the car was completely stock and when i hammered on the gas it never missed and I could only get 9-10lbs of boost than. The past two days I installed a Injen CAI, Injen Upper intercooling piping, and I installed GM stage 1 sensors and I got a brand new PCM from ZZ performance tuned and it's tuned for the CAI too. Got everything in started it up let it warm up about 140 slowly drove through town got out on some back roads and hammered on it got up to 12-13lbs of boost and started missing and jerking and just ran horrible when it got up to around 4,000 RPMs. Got home everything is good. No intercooler pipes blown off or anything. Everything's tight. My clutch is good, No check engine lights no pending codes either. Anyone have any idea what's going on here?? I figured I'd ask you guys since this is the place i always come if I need advice! Any help would greatly be appreciated! Thanks guys!

 

machine gun popping sound?

 

Nope no machine gun popping sound..just jerking missing no sounds nothing

 

So your car didn't run right and you decided to throw on mods and a tune on it?

Maintenance before mods.

 

Read above^ it ran fine before. No missing or anything. Im only thing I said was it only would boost to 10lbs before...no missing Or anything.

 

Pretty sure 9-10lbs of boost isn't normal. Even with perfect atmospheric conditions you wouldn't make max torque on that boost level.

 

I heard people say that your car adjust for the weather, all that ETC. it never missed when stock put this stuff on and it's missing now when I get on it. Is it the plugs? That boost control solenoid?? I need some ideas here, I'm going nuts.

 

Never heard of 10lbs being normal. I usually make 14-16lbs stock.

We can't tell you what your problems are. Could be plugs, could be a bunch of stuff.

 

Give me some ideas...I just wanna know what the heck causing it to miss now?

 

Sounds like your car had issues and mods made them worse. Check the basic maintenance stuff and look to see if everything is installed correctly.

You changed stuff and things got worse. Kinda easy to start diagnosing the issues.

 

But what would cause the car only to boost to 10lbs stock? And it DIDNT miss at all than..just only got 10lbs of boost ran fine.

 

Make sure the MAP sensor wires aren't being smashed by the ac compressor/condenser whatever it is. I had that problem for the longest time. Also could be spark plugs, or coil pack wires but I would say the MAP wires first.

 

Is that the lower MAP sensor on the cold side (I believe) intercooler pipe? Is that where your talking?

 

Because I installed those GM sensors and that bottom one on the pipe was a bitch to get in and was tight against whatver it was I didn't pay attention.

 

"Let it warm up to 140"

You should never hammer under 165F ATLEAST or else you will get misfires but you messed something else up.

Check your spark plugs. You probably messed them up and made made them too small or gapped them bigger while installed. I think you're getting spark blowout.


This is on an LNF right?

 

It was at 140 I said when I took off drove thru town..it was 175-181 when I got on it

 

Yes LNF too. My signature is for my 06 SS/SC I had won't let me change it. And I didn't change the plugs in it when I did all this. But I did order new plugs and coils.

 

Throw parts at it. That'll fix it....

 

yup probably will huh

 

9-10 psi? whats the ambient temperature? better be like -20*F.

9 - 10 psi sounds like some sort of boost leak but I would think you'd be seeing a CEL for sure. Dead turbo? Swapping the ecu for a tuned ecu and you only saw 13 psi max really feels like somethings up with the turbo. wastegate was adjusted?

 

That's all I could get out of stock turbo and that was like 40 degrees outside. And new PCM I got to 13kbs before it started jerking and I let off tried it again same ****. About had it already with the car lol

 

No thats not right. Theres something wrong. put the car back to stock, you have a way of monitoring any data? fuel trims? AFR? I would be seeing if everything is in order and probably checking the turbo. I have no idea how to know if the wastegate is functioning correctly but Id look up how to check on adjusting it or seeing someone with some experience adjusting the wastegate.

compression check.

 

I can check it out..it ran fine didn't miss or jerk when it was stock but I only got the 10lbs. I figured maybe a boost leak but i did a test and couldn't hear anything hard when I'm by myself. I'll go through it all again busy with work and re doing my basement so my times limited thanks for the help

 

yea 10 psi is a big red flag. 40 degrees you should still be seeing like 15 psi at least. Thats not a boost fluctuation with temperature changes. Wisconsin isnt a low below sea level state is it?

 

So your thinking wastegate possibly?