All the mods in my signature are now on the car, and I'm running a fairly mild tune on the E-manage. The EGT reads pretty safe; peak temps are about 790C. I replaced the spark plugs last night to NGK BPR7ES (gapped at .028) - the stock #1 and #4 were fouled, #4 being the worst.

I am getting a really annoying fuel cut issue; it's to the point where it happens to me even at 15psi occasionally. I can usually just ride right through it, but it is very aggravating and keeping me from running good times at the track. The car will be pulling strong and then it will suddenly backfire and jerk.

On the advice of a friend with a lot of DSM experience, he is thinking it is probably something with the MAF reading too much air and cutting fuel. I have an AEM intake on order, and we believe this might solve the fuel-cut issue, but I wanted to check and see who out there might have advice or experience with this.

We tried leaning out the mix to no avail. Any help / suggestions are greatly appreciated.

 

misfiring usually leads to backfiring, check the air/fuel mixture and ignition timing

 

ZHonestly?? Pull your plugs out and Gap them to .20, that simply. You are running WAY more air through that engine, and the spark is hurting. I did th esame for my DSM and it stopped jerking and cutting.

Just try it and tell me how it goes, you can allways go back, but the .20 will do the trick.

 

I gapped my NGK BPR7ES plugs to 22, I have had no problems running high boost. Does the emanage have a way to tell what the max reading from the mass air was. I know mine hits fuel cut around 1900hz at wide open throttle

 

First off take out the copper plugs. Especially copper plugs with the SAME heat range as the stock iridiums. Iridiums are light years ahead of copper plugs.

Either run some BPR8ES copper plugs, or just get some damn HKS S45G iridium plugs (heat range 8). They are like $15 a piece but well worth it. Oh and the stated plug gap is only for iridiums - .024 to .026 on the iridiums or .026-.028 for coppers.

 

I regapped the spark plugs to .022 - .024 and it did not make a bit of difference.

Then I decided to tweak with the ignition advance that was setup. Here was the original % advance per RPM :

(this is all at Karman vortex airflow readings of 600 to 3000, slightly different and less aggressive numbers for lower airflow readings).

RPM Advance
---------- ------------------
2500 2%
3000 4%
3500 5%
4000 4%
4500 4%
5000 2%
7000 -1%

That was a borrowed AMS tune which worked pretty well when it was hotter outside. I switched it to this and the cut / backfire went completely away:

RPM Advance
---------- ------------------
2500 2%
3000 4%
3500 3%
4000 2%
4500 1%
7000 -2%


Just wanted to throw this out there as something to try for anyone else who experiences this problem.

 

among all the mods you have I see no kind of fuel upgrade. You're running with 272 cams and original pump, injectors - maybe not the way to go. I would definetely at least upgrade the pump, but injectors should also be added to your recipe. You can run more timing by richening up the mixture a bit.

 

AS long as you are on the stock turbo, stock fuel setup is fine. The stock system is good for 400WHP, which is right when the stock turbo is maxed out.

 

My injectors, pump and fuel rail won't be going in until the new turbo goes on. There are shops running high 11's on stock fuel setup and turbo, which is what I MUST do before upgrading any further.