Sputter @ Transition from Vac to Boost

[rico05]

I say vac leak (can't find one but oh well), but I just wanted some feedback. I get a pretty bad sputter as I transition from vacuum to boost. Starts @ 3inHg and lasts until about 2-3psi. If I hold the throttle so that I get right at 0inHg, it just bucks and pops. It's not noticable if I am seriously romping on it, but part throttle it is pretty bad.

[float_6969]

When was the last time you cleaned the MAFS? It could be a vac leak, but it must be pretty minor.

[kapower06]

quadruple check for any boost/vacuum leaks, then check again. Also what MAFS are you running? whats your set-up? Also is the ECU throwing any codes?

[driftin8ez]

Do you have a 255lph fuel pump and stock fpr? If so it was determined in a thread about a week or two ago that the stock fpr on the CA gets over ran at the transition between vac/boost making your motor run rich. Well your stock fpr will always be over ran with a 255lph fuel pump but the transition between vac/boost is when you run super rich and get the hesitations and sputters. If you have an after market fpr did you set it correctly?

[rico05]

KA24E MAF, hasn't been cleaned .. um... ever lol.

No codes, and my boost gauge shows 20inHg at idle, so I am not totally sure about the vac leak.

Walbro 255lph, with Nismo FPR set as per Ryan's how to.

I *think* I have a leaking injector, and I just bought a set of 450s from Chris, so I will be rechipping here soon and that might fix it. Argh.

[float_6969]

Rico, keep us updated on the status of the problem. You might get some MAFS cleaner as well. It certainly can't hurt. If it is a leaky injector, that could cause your problem as well.

[rico05]

I'll pick up some electric cleaner at work tomorrow. I'll keep you posted Ryan.