I just got done installing my custom t4 gt35r turbo kit along with 1000cc injectors, I have all other supporting mods and im on stock motor and head. Just switched out the plugs to bpr8's gapped at .26

I took the car out to do some baseline tuning today and scaled the injectors to 880cc injectors and leaned out the car a little bit.... afr's on my wideband were consistant at 11.2 and there was 1 count of knock max on the logger with max timing at full boost at 6-7 (28psi and 110octane).... The car still felt rich as hell and at 6k the power would cut out.... felt like fuel cut.... I changed around the settings a bit, switched afrs..... scalled the injectors back to 513's, leaned out the car a lot, turned down the boost to 26.5psi (afr's showed 9.2-9.8!! pig rich).... nothing is helping this hiccup at 6k, Does anyone have any idea's at all what it could be? Even with the afr's showing 12.0 the whole time in boost it still had this hiccup. I am completely stumped.... By the way these runs were done on 110 octane if that matters at all.

Hopefully someone here might have a solution to this problem because my car has to go on the dyno tomorrow morning so i need this figured out by then!!! I am going to do a boost leak test when i get home from work today and then try to lean out the car a lot more with injectors still scaled at 513cc... if that doesnt work i will try some more tuning scalled at 880's....

 

I get the exact same thing at about 6k I get what feels like misfire.. Too rich can lead to misfire and knock too..

Try gapping your plugs down a bit more, I'm running BPR9ES plugs gapped at .026 but the car is running rich and I suspect the misfire may have something to do with it being a little rich and the gap a little large.. If you don't have an HKS DLI2 or some sort of ignition amplifier, you may have to gap down to .022

 

Just make sure your not missing obvious things like the boost cut timer and of course the fuel cut settings..

Don't feel too bad, everyone has these issues to work through though..

 

Thanks a lot Malibujack... yea when i got the sparkplugs from ams they were gapped at .24 but i thought that might be a bit low.... i'll gap them a little lower and see what happens, as far as the scaling is going, do you think i should scale my injectors for 880's or do you think i should leave them as stock and just start leaning out the maps?... i am always watching knock and my afr and like i said, ive had a max of 1 knock count.

 

I would scale them, but leave the scaling a little rich (the correct way is to scale them to around 600-625, adjust the injector latency, then fine-tune it until your trims at idle and cruise are close to 0, [100% in evoscan]) That should make the AFR value on your maps somewhat mirror your actual AFR (it won't be quite right, but make your brain hurt less)

 

What do you have your boost limit settings at? Sounds like your hitting boost cut.

Raise them *****es, up!

 

Its possible he overlooked that setting.. But I know what he is describing because my car has been doing it recently.. I don't have oodles of time to tune my car so I'm lucky if I can try a new map every couple of days..

I do think that I am running a little too much timing for my quality of gas in the 4000-6000rpm range.. but being rich, and having questionable ignition quality can also be the source of my issue, which in turn is likely similar for him.

 

I have 750 and I scaled to 750 after trying various lower scalings and latencies. I found this to work the best for me. I barely had to do anything with the WOT fueling and I found that I still had to lean out the part throttle, light load cells to get the trims to stay around 1-2%.

 

Thanks for the info guys... im at work right now so i'll look over my logs again and i'll check my boost limiter, it might be that because we tuned my buddies evo 9 at 31psi on 110 last night with a 35r on it and it ran perfect. He had 880's scaled to 513... 11.1-11.2afr dropping to 10.9 and 1-2 counts of knock max... we are going to attempt to lean the car out some more today. We will both be on the dyno tomorrow so we will post up our #'s after the dyno day

 

I definetly need to lean out my part throttle... its running extremely rich right now

 

Not every injector will respond that way.. the more similar to the stock design the injectors are, the closer it will be when you scale it.. but its a trial and error type thing, and I have found there are too many variables to just suggest putting in the actual injector size and nothing else.. I always start smaller, and work from there..

FWIW, My injectors worked best with 760, with 11v@ 1.2ms, 14v@.94ms Latency (1000cc Buschur Injectors) for my combination of parts, keeping in mind I have a blowthrough MAF, gave me the closest fuel trims, and the arbitrary AFR numbers in the map, are fairly close to the actual AFR to the wideband..

 

Yea thats exactly why i didnt want to scale the injectors to 1000cc right away because they probably actually flow like 940cc so i thought i would start off on the safe side and scale them for 770's to start... and i had that hiccup at 29psi, then i scaled the injectors to 880cc and turned down the boost to 26.5psi and the car felt more sluggish but the cutout was prolonged by like 400-500rpm... Im going to pull out my spark plugs and check them when i get home, do a boost leak test, and then try out a few things with the injector scaling and afr/timing maps.... also like i stated i was only running 6-7deg timing max and these runs were on 110 so i might start bumping up the timing a bit. thanks for the help... keep the suggestions comming!

 

What scaling values are you using for the various sizes of injectors ? 880's would translate to what ?

 

Thanks for all of your help guys! I gapped the bpr8's to .24 and the car still had that issue at 6krpm and 26.5psi.... my buddy started looking over the flash and we decided to raise up the boost limiter even more, did a run.... no more hiccup at 6k! the boost limiter was set to low so it was cutting out my power at 6k! Now im running 29psi and im very happy with the results

 

I completely agree. Would not suggest that anyone start out with scaling at the injector size. Even though this is what I'm using I stiil had to alter the cells in the fuel map - just not as much as with lower scalings. I started around 620 and moved up in 30ish increments. Latency is 1.2 @11v and .768 @ 14v.