Hello, I have a S13 SR20DET blacktop in an s13. cI have alot of mods on it but my problem is the car sputters and bucks when i give it full throttle an hit about 5000 rpms. It runs just fine at half throttle or even 75 percent. I have checked for boost leaks and found several small ones here and there but i fixed them and it still does it. Are there any sensors perhaps that could cause it. Im running 550cc injectors and a z32 AFM. I think it could be my ECU but im not positive. Any help would be appreciated!

too much gas..

It runs like its not getting enough gas. Any other ideas?

welcome to Nico, both of you, the easiest way to get answers to your questions here on Nico is to use the search button, the amount of info here is mind blowing.

Knowing a little more about your setup will help us solve the problem, what are you using for an ECU, is it a stock unit retuned, or are you using a piggyback or standalone. Have you noticed any other symptoms, any smoking, or spark plug discoloration? How much boost are you running? What kind of Spark plugs are you running and what are they gapped to.

again welcome to Nico

I have a tuned ECU, im using iridium plugs, they are gapped correctly and look pretty good when i pulled them. Im running about 12 PSI of boost. The car does not idle very well either it reads about 10 KG on the boost gauge at idle and it pretty rough. When I first got the ecu back it had the problem very slightly but it would still wind up good and pull hard to redline it would just hesitate every now and then.

My alternator went out and i replaced it, the car sat for about a month and when i started driving it again the problem had gotten worse. Now it bucks and sputters everytime I give it full throttle. I was hoping the ECU just had to reprogram itself but it doesnt seem like this is the case. It acts like its just not getting near enough fuel when i give it WOT. It has been giving me this problem for awhile on and off even before i upgraded the injectors and MAFS/ECU. It would sputter when it got into high bost around 12-14, but then i figured it was the injectors or MAFS hitting there max but I know that is not the case now. Any suggestions would be very helpful!!

The spark plugs are gapped at about .40 or 1mm i went by what it said on the shift 180 video. I seen in some other post people talking about gapping them to like .30 is my gap to big?

Jonsr20 wrote:The spark plugs are gapped at about .40 or 1mm i went by what it said on the shift 180 video. I seen in some other post people talking about gapping them to like .30 is my gap to big?

for anything above 10 PSI you want between .028 and .032, if yours are at .040 Im guessing your getting your spark blown out because of the large gap, regap them and see what happens.

PS see what I mean about searching, it works super good

check your timing..I have to crank the cas fully clockwise.

good luck

The spark plug gap did it!! Its a monster now, any ideas about the rough idle? 10kg on the boost gauge is pretty bad isnt it? Thanks alot!!

Im not sure about Kg, most SRs ive seen, including mine pull around 20 inches HG at idle, you could have a vacuum leak somwhere, or its possible your tune is dumping in too much fuel at idle.

if you're using NISMO 555cc injectors, they are actually 615cc... and they tend to idle a little rough due to that difference in advertised and actual flow capability. who did the ecu tune? i would agree that it could be a rich condition at idle causing it.