so check his out, I have a 2011 GMC Sierra 4x4 with the 5.3 and I had a custom root superchgerkit built, thing is awesome BUT it is mis-firing only on cylinder number 4 at idle but when I step on it, the thing hauls and its smooth. I have taken it to a tuner and he can not fix the porblem, I have legit $1000 injectors, new plugs and have done everything to troubleshoot including swapping injectors, spark plugs, coils, wires even pulling the valve cover to see if the spring is damaged and nothing. Did a leak down test, compression test and everything is on point. My truck has less that 10k miles on it. So im currious, does the active fuel management have something to do with it? Also my service light flashes sometimes which means misfire and I get codes where it says service traction controll, stabila track and othe stuff when its at idle. But again, I get on it and it moves. I have my guy that built the kit pull it apart 3 times and everything is fine. He has built a bunch of custom stuff an I have not had one issue with his work so I dont think its his design. Its an open plenum manifold and all other cylinders dont mis-fire except cylinder number 4. I am starting to think it is a tuning issue but my tuner disagrees. I am in southern Cali and I am to the point where I want to put it back to stock and sell the damn truck. Any help would be great!

 

Here is your original thread

https://www.performancetrucks.net/fo...e-help-506295/

 

Never knew injectors cost 1000 bucks but sounds like a personal problem to me also sounds like a bad ground wire

 

it was 1000 bucks for all 8, personal problem? dunno how that could facter in what is wrong with my truck.

 

He's talking about the injectors being $1000... Flow matched 60's are way less than half of that.... you were had.

I also agree with the other thing he said. It sounds like you've got a wire not making a good connection somewhere. If you are thinking it's a tuning issue, take it to another tuner and see what they think.

G'luck!

 

I bought injector dynamics injectors because I was told they were the best injectors out there and there was tons of tables out there to get the perfect tune. Where can I check for grounds for the injectors? I pull the plug on the injector while the car is running and it runs worse.

 

Check Ur spark plug wire coil pack mis fire is sometimes caused by spark plugeg not being gapped enuff had a problem like that before so good luck man

 

yea, already did that, and swapped plugs, wires, coil packs

 

Check Ur ground wire to the passenger side head and the frame ground trucks has 2 grounds other than that I can't tell you much more could have burnt a hole in the piston have you took the head off other than that my
Friend I don't don't what too tell you check all your plug wires to your injectors stick a voltage meter on them like a test light and test them frist before taking the head off

 

Have you asked for a smoke test to check for a possible vacuum leak? You said it's a custom built roots supercharger setup. Can you post a pic or two? Is it a sheetmetal manifold? If so, maybe a pinhole in a weld or something similar could cause just one cylinder to run lean & misfire at idle, or when driving with light load in vacuum, but still run good & strong in boost.

Some more info about your custom setup would be helpful.