So a few months back my cylinder #4 was having minor misfire during cold starts that would occasionally turn on the CEL. So after many trips to the dealership they finally replaced the fuel injector on that cylinder and the problem seems to be completely gone. Now my cylinder #3 is misfiring!! This time it's not just on cold start. In fact cylinder #3 is hardly firing at all. Sometimes it acts like it wants to accelerate like normal, but then chugs and cuts out and the misfire counter on my dashdaq starts going crazy. CEL flashes then stays on steady. So I'm thinking that the injector for cyl 3 is now the problem. Does this sound like an injector problem or something else? Oh, and btw this first started happening a few days ago when I was in 2nd gear and easing into the throttle (no NLS or hard acceleration). Any input is appreciated. Thanks

 

Maybe a coil pack.

 

Turns out it was a coil pack. Lol. They had the part locally and I had my car back the same day.

 

How many miles do you have on the plugs since the tune?

Keep an eye on em.

 

my ss tc also read misfire in cylinder 4 and drove perfect until i changed the plugs then any time i put the accelerator down to the floor she misfires today i changed all the coil packs and the CEL shut off but it still misfires when the petal to the a floor over 4000 rpms need suggestions

 

Sounds like plugs. I had the same issue

 

I imagine you've already tried swapping spark plugs with one of the cylinders that is not misfiring? If it still misfires in Cylinder 4 I would be suspicious of the injector.

 

Ummmm have you tried to get the one step colder Ngk plugs, since you have a tune, and like someone earlier said how many miles some people like a friend of mine got his tune than also got the Ngk one step colder plugs n everything is good.

 

Mine won't run on stock plugs with a tune. I had to go two steps colder I think is what I went

 

i am a jack ass and didnt gap my plugs right but now shes runnin ***** to the walls thanks for the suggestions.

 

another thing maybe you guys maybe able to help me with is how to tell if your ride has a tune? i read on one of the balt ss forums that stock boost should be about 15psi give or take i hear outside temp can affect it i live in minnesota. but when i put the gas to the floor i hit atleast 22-23psi. so my question is having a higher psi a sigh of an aftermarket tune??

 

You have a tune most likely.

 

Mine misfires a lot of times when she's in cat warmup, I'm on my 3rd set of plugs in 40k. Changed in the last 1k cause cyl 4 broke the insulator and was floating around. Gapped the Autolites to .033 less than 2 weeks ago and just this morning she tossed a cyl 1 misfire during warm up. Wth?

 

Damn I heard people using the NGK PLUGS 3787 I believe or I could be wrong. Is that what u guys that have a tune think I should do have 43,000 miles on stock plugs, if so I'll change them

 

yep, that's what I use, NGK 3787. They've been great since I got tuned. About 10k miles so far. I'm thinking about changing them soon. Don't want to have any problems.

 

Really whT kinda problems did you have with your stock ones. Anything

 

not a fan of autolites had bad luck in other cars.

 

you def. have a tune. for ***** and giggles turn on the cruise control button and stomp on the gas.

 

what do you mean? i think i remember reading about a specific tune that incorperated the cruise control but i believe that also disable your lean down feature which is the launch control not the NLS feature but my car still still only revs to 4500 on the startng line

 

I want to see if you have a trifecta tune. turn on the cruise control button on steering wheel. light will be on. go down the freeway and stomp on it in third gear. My guess is you will only boost 15psi with the cruise on.

 

ok i will check that out is that just cruise control on when car is on no switching the tc or esc or comp mode??

 

Being an 08 could be the old non switchable tune. Superchips, Hpt, or gm stage 1 hard to say. Have him check the map wires if not trifecta.

 

The switch can be either cruise control on/off or comp/esc off either one. Or the older tune no switch.

 

map wires??

 

you could have a gms1 tune installed in your car. the 2bar map sensor is swapped out for a three bar sensor and the wires are spliced and soldered together.