Need help, sr problem!

[Gutling]

Alright, I have a 1989 nissan 240sx with a redtop sr20det. I recently put it in the shop to have a bunch of modifications done on it, the current setup is a Greddy GT25R (not the 400hp one, basically a stock replacement, bb) Sard 550cc injectors, turbonetics mbc, hks bov, front mount intercooler, megan o2housing, 3"downpipe, 3" megan exhaust, z32 mafs nismo intake, walboro 255, ssautochrome exhaust mani, SAFC II, blitz turbo timer. Anyway, the problem i was having started before the injectors, turbo were installed. The car would crank fine, rev up freely in neutral. however in gear, it would pull fine till ~3000 rpms, or if you slowly eased the gas a bit higher, then it would stutter horrible, and drop rpms to ~1000 until u released the pedal. u can keep it floored and it will never go about 1000. stuff i have checked/replaced. redid the mafs wiring from the ecu, it was butt connected 3 times and not chassis grounded at the mafs. fixed that, still did it. switched out the z32 mafs with one from a j30, still did it so mafs is good. that leaves me to believe it is the ecu. i have ordered a new oem one, and will have it friday. but is there anything else i can check, try out, wiggle, replace? voltage on the mafs, it would run fine until 3volts, u can keep it at 2.9 and drive it all day, the miute it hit 3 it would drop to 1.

[s13sr20chris]

did you have the safcII when the prob started? i wonder if the ecm is wigged out about your changes to the maf and injectors.

[Gutling]

Yes, the car ran good till about a week before i put it in the shop for the turbo and injectors. it had everything else before then incl. safcii. so i know its not new part related, or due to any changes. it would do it, then go away, then come back, finnally it was doing it all the time. i put it in the shop, hoping after the work got done on the turbo and all they would see something. but they are stumped now too.

[s13sr20chris]

so you had the afc with maf and then did the turbo and injectors? you may have hit the wall of adjustment the afc is capable of. 50% is the most it can compensate for but 10% is the most you can do without the ecm freaking out. thats what hks, apexi, greddy, and jwt say anyway. nevertheless it could be something else.

i want to say its maf/circuit related but it could be something like valve timingignitionboost/vac leaketc.

i would check maf voltage at the ecm by backprobing and make sure you are getting proper voltage at ecm(to eliminate wiring).

[Gutling]

Yes i had everything listed except turbo and injectors, and it was doing it. it was doing it with no adjustment on the safc. so check the voltages coming out of the ecu? what should i be looking for?

[s13sr20chris]

the safc modifies your maf voltage to compensate for maf and injector swaps. if you had a z32 maf and did not compensate with something then that was a problem right there. then if you slapped in the injectors and did not compensate then that is another.

[Gutling]

Well, hopefully solved it. Mafs was good, mafs wiring was good, swapped out ecus and ecu was good. I think the safc is altering too much for the ecu to handle. I getting a enthalpy tuned one hopefully by tuesday, and getting rid of that devil safc :P thanks for helping s13sr20chris, hopefully this new ecu will help.