dumping fuel and slow building boost?!?!?
The Car:
92 G20
SR20DET U13
GT28R ball bearing
444cc injectors
z32 MAF
JDM U13 ECU
SAFC II
AEM UEGO Digital Wideband
10psi boost
Not sure if fuel pump is stock or not (based on other supporting mods I'd expect not)
So here's what's going on...when tuning WOT fuel map with SAFC, from 800rpm-3600rpm Im only pulling out -14 to -18 percent fuel to maintain a a/f ratio in 11.5-12.1, but from 4000rpm-7000rpm I have to pull -26 to -32 percent to maintain that range!
Vacuum at idle is 21inHg
This is the other interesting point:
initial boost builds at 3200rpm to around 1-2psi, at 4500rpm is 5psi, and at 5500rpm peaks to 10psi and holds to redline...it doesn't taper off once it peaks like you'd expect from a leak.
I pressure tested anyways (home depot diy to compressor inlet and cap at the end of hotpipe just before throttle body, soapy water spray to look for bubbles) and DID find two leaks...one was right at the gasket for the compressor inlet plate (horrible welded mess with uneven plate side), and a pinhole in the rubber line that connects from my manual boost controller to the intake pipe just before the blow off valve and throttle body.
The first leak would effect vacuum not boost, but nevertheless I put a bead of copper rtv to seal that up. Replaced the line to the MBC with new rubber...new pressure test holds 20psi just fine. Take the car out and the only thing different is that it drops into vacuum faster when letting off the pedal...rate of boost climb is the same, a/f ratio is the same with same safc settings.
Im at my wits end here! Having to lean out on the safc on the top end (as boost starts) would indicate that the engine isn't seeing the air that the maf is metering, but there are no boost leaks? It also doesn't line up with the slow building boost...
What am I missing here guys/gals? From researching a GT28 should hit full boost before around 3600-4000rpm.
Next two things I can think of would be wastegate and MBC...how should I test to see if either are faulty?
Sorry, throwing a lot out there...
92 G20
SR20DET U13
GT28R ball bearing
444cc injectors
z32 MAF
JDM U13 ECU
SAFC II
AEM UEGO Digital Wideband
10psi boost
Not sure if fuel pump is stock or not (based on other supporting mods I'd expect not)
So here's what's going on...when tuning WOT fuel map with SAFC, from 800rpm-3600rpm Im only pulling out -14 to -18 percent fuel to maintain a a/f ratio in 11.5-12.1, but from 4000rpm-7000rpm I have to pull -26 to -32 percent to maintain that range!
Vacuum at idle is 21inHg
This is the other interesting point:
initial boost builds at 3200rpm to around 1-2psi, at 4500rpm is 5psi, and at 5500rpm peaks to 10psi and holds to redline...it doesn't taper off once it peaks like you'd expect from a leak.
I pressure tested anyways (home depot diy to compressor inlet and cap at the end of hotpipe just before throttle body, soapy water spray to look for bubbles) and DID find two leaks...one was right at the gasket for the compressor inlet plate (horrible welded mess with uneven plate side), and a pinhole in the rubber line that connects from my manual boost controller to the intake pipe just before the blow off valve and throttle body.
The first leak would effect vacuum not boost, but nevertheless I put a bead of copper rtv to seal that up. Replaced the line to the MBC with new rubber...new pressure test holds 20psi just fine. Take the car out and the only thing different is that it drops into vacuum faster when letting off the pedal...rate of boost climb is the same, a/f ratio is the same with same safc settings.
Im at my wits end here! Having to lean out on the safc on the top end (as boost starts) would indicate that the engine isn't seeing the air that the maf is metering, but there are no boost leaks? It also doesn't line up with the slow building boost...
What am I missing here guys/gals? From researching a GT28 should hit full boost before around 3600-4000rpm.
Next two things I can think of would be wastegate and MBC...how should I test to see if either are faulty?
Sorry, throwing a lot out there...
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