My car sputters/misfires after the throttle is engaged after 2,000 to 4,000 rpms. It varys when i t misfires it sometimes wont even misfire. The code always comes up as p1399 but it has also read Misfire cylinder 1-4 too, so it isnt just one cylinder. When it engages it is a sputter more then a bang bang sort of thing. Kind of sounds like rev limiter but with a softer noise. I have tired the following things to try and fix and none of them worked. Here is how the problem stared, I drove to lowes went inside, came back out and started it up and drove off and it started misfiring, (flashing check engine light) wasnt hard on it and ther was no boost at the time. No clue???? Here is what i've tried so far.
I changed spark plugs
I changed spark plug wires
I changed the distributer cap and spinner
i changed the coil
I checked all the grounds
I changed the fuel pump
I checked the fuel pressure on the after market FMU
I disconected my safcII
checked the connections on the main ECU
checked compresion 135 all the way across
vacum is good at 18 psi
I'm clueless please help I'm open to any suggestions the following is what is done to my car

D16y7 1999
t3/34 turbo
Big intercooler
hks wastegate
greddy BOV
Blox FMU
Fluidyne Radiator
nology wires
Gsport Coil and distributer cap
2.5 exhaust all the way to the Flowmaster muffler
Iridium spark plugs
SafcII
Holley Walbro 255 pump
JE Srp 9.0-1 Pistons
Eagle H-Beam Rods
Arp Bolts
Ported polished head
AEM Cam gear
and I'm only running 6psi, I just got my wide band in so that i could put my 450cc injectors in to up the boost and it started running like crap please help figure out the problem

Thanks a Bunch

 

I'm not much for turbo's exactly, but it sounds to me like you don't have enought spark and your injectors are too big, like ther's too much gas and your "flooding it". Do you have ignition upgrades? If not, I would suggest jumping on that to help you out... such as your coilpack and distributr, plug wires and plugs only help if you've got the juice to deliver that much power.

 

I do have alot of ignition upgrades, coil, wires, plugs, and i tested all of them and i'm running on stock fuel injectores, if the case was to much fuel it would clear it self out when boost ingages but it doesent, it still sputters/misfires

thanks for input though

 

It actually wouldn't clear out when the turbo kicks in, it would just lean way out and cause a "balance" if you will. Both you fuel and air are off the wall, but they are both so far off that they even out. That was my guess.
So the status now is you are on the stock injectors and you are still sputtering. This may sound stupid, but check your intake. all the way to your manifold, make sure nothing is restricting your air flow. If not that then I don't know what to tell you. What kind of sputtering is it? Like a chugging? Is your timing off maybe? Because your timing advance would even it out when you rev'd your engine. Check your timing. Also, what was the last mod/change you did to your car before this started happening.

 

I didnt do anything, is the thing, it was running great, went to the store went in and came back out and started it up and it started running like ****. my intake pipe is clear from what i can see, keep in mind it is all intercooler piping. what i dont get is it ran fine theni started it up and it started to run crapppy, the sound is like a chugging noise and it jerks if i open the throtle all the way. i eraced the codes and left the battery disconected last night and the codes came back on on my way to work this morning.


p0301 misfire cylinder 1
p0302 "2"
p0303 "3"
P0304 "4"
P0300 MULTIPLE MISFIRE DETECTED

p1399 misfire/ignition

thanks again for the inpute

 

You have the wideband now, why not install it and see what your AFRs are at closed loop and open loop. that will tell you how far off your mixture is. You might also want to check your fuel trims and see if your ECU is trying to compensate for a bad sensor of some sort(i.e. O2 sensor, MAF sensor,...) with the wideband and the OBDII you should be able to see how your ECU is reacting and if that could be the problem. It does sound like air/fuel mixture or timing issue. Another possibility is spark plug gap. I know you said you replaced them, but were they gapped properly. Did you check to see if that little nut at the end of them are tight. i have seen it many times, that little nut is loose and there is a bad connection or the gap is incorrect and you get misfires. Just a few things I can think of. good luck and let us know what you come up with.

 

Well i fixed it, it was casued some sort a white material getting stuck in two of the fuel injector filters, blew out the filters and replaced the main filter and it runs better then it ever has before.

Thanks for the input guys, i will do my best to give you guys my input on your problems