tranb000

So just got my car tuned and brought it home. Took it for a drive and it wont idle right. It will raise up and down and sometimes even stall out. Before i took it for a tune i installed 60lb injectors and new spark plugs. At the tune they realized it wasn't quite right, they were having problems with the fuel trim. Put new o2 sensors in and still wasn't right. The p0300 code for mulitple or random missfire keeps coming up when the car is idling rough. The car has shorty headers, borla cat back, jessel roller rockers, ls6 intake, d1sc procharger, racetronics fuel pump with hot wire. The car only came up with 442hp to the wheels I was expecting closer to 500. The car ran and idled fine before the new part install and tune. I just don't know where to start if it is the plugs or injectors or really where i should start. Just really frustrated right now.

JAX04

iTrader: (17)

check your plugs, also is the car tuned SD or MAF?? you might have a vaccuum leak somewhere if you cant get it to idle properly.

mulitple misfires huh?? which cylinder is it??

is the shop that tuned this a reputable shop or just "a friend". Or "some guy"?"?

need lots more info. I would first check your plugs and all of your vacuum lines.

tranb000

The car is maf and has the stock mass air flow sensor. It did not come up with which cylinder is misfiring just comes up with the p0300 code each time. The tune was done by a reputable shop. My sisters bf is a mechanic and when he gets time this week he is going to connect it to a scanner and see if he can find out what's going on. I will start with the plugs though and see if that is the problem, i'm using the tr-6 plugs.

TurboAv

iTrader: (6)

If you install bigger injectors the computer need to be changed for the new injectors. Was this done?

So.jerZ-28

iTrader: (20)

what brand injectors? just a little caution here from experience...... I called F.A.S.T. for injector part #'S for 60lb. injectors.
Ordered part # they gave me.
Had dyno tune done and tons of running/idling etc.. problems
after futher inspection found out that the injectors were low impedence injectors !!!
f.a.s.t. does not label on the package if low or high, had to do little research to find out that they sent me wrong inj.

tranb000

They are 60lb high independence delka mototron injectors that were flow tested. I thought i would finally be done with this car racing challengers and vettes on the road. I just need this done because i haven't been able to drive it all summer and summer is almost over up here in Wisconsin.

Bob@BruteSpeed

iTrader: (16)

The shop that tuned your car for you should not of sent you on your way with it having problems. "Took it for a drive and it wont idle right. It will raise up and down and sometimes even stall out." Did the shop even take your car out and drive it? Bob

tranb000

Ya they cruised it down the road twice but it never stalled on them but the idle was acting up for them. I trailered it there and home so i drove it when i got it home. Hopefully i can figure it out why it is misfiring and having the idle issues then i'm taking it back and having them retune it i paid a lot for it to be tuned in the first place.

tranb000

So my mechanic hooked up a scanner to the car the other night and it idled fine at first and then started running rough. On the scanner it showed that every cylinder would randomly misfire. He thinks the 60lb injectors are too big and flooding it out but i thought at the tune they would be able to take care of that. So now I'm putting my 42lb injectors back in it and taking the ecu to the tuner for them to flash it and see if that fixes the problem. Then I'll have to get it tuned again. How fun.

So.jerZ-28

iTrader: (20)

is the car cam'd?heads? if the car has h/c w/d1sc and other mods, I would say 60lb are right on the money.

if just bolt ons w/d1sc, than 42-46lb injectors would be the way to go. thats my .02

tranb000

Just bolt on's I'll find out tomorrow, I switched back to the 42lbs and getting the ecu flashed tomorrow. We will see if it fixes the problem then its going back on the dyno. I just better not have to pay anything out of pocket.

tranb000

Got the ecu flashed and the car is running a lot better doesn't stall anymore. Now just have to find time to get it back down for a tune. I want to go through the supercharger stuff before i take it down there again. Was only seeing 7lbs of boost on the dyno and was expecting around 8-9. Have a 4.5 inch pulley on the supercharger. I want to check my surge valve to make sure it's closing all the way. Also on the dyno before the power broke up at 5500 rpm. I'm hoping it did that because of the injectors. They said I need valve springs but i just can't see it when the motor only has 19k on it and stock cam.

XtremeDime

iTrader: (16)

This sounds oddly like Q's problem when he was trying to tune his out a couple months ago. He had 60# seimens also and ended up going with 42# injectors and it cleared up.

MUSTANGBRKR02

iTrader: (91)

If you have stock springs then you are most likely seeing float. I am in the process now of changing mine for the same reason. You will not always see full boost on a dyno depending on the type.

tranb000

Thanks for the replys the more i learn the better