Hello. I have a turbocharged gsr sedan. I just recently put on some RC 440cc injectors and Apexi VAFC-II VTEC COntroller. I am only running 7PSI. Once i had put that in, My car stutters when I have the throttle over 40%. For example.. I would be in 2nd gear at 2000 rpm and hit it and as soon as my boost gets to around 5 psi it starts to stutter usually around 4000 rpm. It's the same thing in all gears. Now if I am in first gear and I push on the pedal normally, it will go to redline no problem. I don't know what the problem is. I am suspecting it is my air/fuel ratio. If anyone can help me.. please do. ALso what can I do to fix it?

 

Isn't that what the VAFC is for? i'm a noob at turbo, but that's what I thought.

 

have you tuned it? do you have a fpr? did you change any plugs while doing this?

 

sounds like a tuning issue.
also check your plugs

 

Honestly, you need to get rid of the fuel controller and get a standalone system like Hondata, chrom, or AEM EMS. That and a great tuning will put you in the right direction.

 

i suspect more research is needed...no offense. was it tuned? u put the turbo on, tuned, and then 440 injectors? when u upgrade on FI a new tune is recommended. if it was tune before the mods u need a new tune on those mods. i would ditch the vafc.

 

no. hasn't been tuned yet. I was just making sure if i needed to get this problem fixed before getting tuned or not. Im planning to tune real soon. Anywhere in particular on the east coast anybody?

 

evans tuning is the man to see. in easton pa. check him out.
good luck. i have the same problem with my ride with a few mods myself and disconnected my vafc, and i'm waiting on a turbo manifold to be shipped then i'm tuning.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TurboGS-Rsedan &raquo;</TD></TR><TR><TD CLASS="quote">no. hasn't been tuned yet. I was just making sure if i needed to get this problem fixed before getting tuned or not. Im planning to tune real soon. Anywhere in particular on the east coast anybody?</TD></TR></TABLE>

Does it ping at all? Most likely I would bet that you are running either too rich or too lean. Like everyone has said, tuning will help

Also, what do you mean by studder? Is it more of a very drastic buck, or does it feel more like the car is falling on its face...like its hitting a power wall or something of that nature. One of those is most likely happening, which would tell you whether you are running too rich or too lean.

 

you could possibly be running rich....if you think about it the 440cc injectors are going to require a shorter duration of pulse to fire the same amount of fuel that a stock ~240cc injector needs. Thus since it seems that you didnt retune it after the 440cc injectors they are staying open too long and put excessive fuel in....

did you run a new base map after you put the 440's in??

What are you using for fuel management?? Just the vafc?? Fmu? Chipped ecu??

 

You are running pig rich because you upgraded the injectors without focusing on the most important part of a turbo setup...the fuel management. A half assed fuel management setup like that will give you half assed results especially when the stock fuel maps are being run and can't compensate for those much larger injectors.

Get Hondata, Crome, Uberdata...something better than what you are trying to use.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TurboGS-Rsedan &raquo;</TD></TR><TR><TD CLASS="quote">no. hasn't been tuned yet. I was just making sure if i needed to get this problem fixed before getting tuned or not. Im planning to tune real soon. Anywhere in particular on the east coast anybody?
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HUGE mistake by assuming this...

INSTALL-tune-drive. A well educated tuner would know RIGHT AWAY if something was wrong. Get your chit tuned, mang.

 

youre running too much fuel, you would have the same problem if you install an upgraded fuel pump, get everything you need first then tune the car. if you tune before you get the injectors you will have to tune again, just as much as other things. after you have all your fuel accessories and you tune you wont have problems with your car studdering.