Spoolpigeon

hey guys, i'm having a fuel issue with my redtop SR. Its running lean at WOT, in the 13.0-13.3 range. it runs and drives well, just goes lean when its in boost. heres a quick list of mods:

redtop with stock internals
decked and ported/polished head
intake
FMIC
3inch from turbo back
255 pump
nismo FPR
still on a t-25 but it has a ported compressor housing
running 10psi of boost

I've been having to crank up the fuel pressure to get it to run correctly. it's set at 55psi with vacuum applied. if i set it so stock, it will run, but hardly move once it has any load. it sounds like a fuel delivery problem but thats where it gets tricky. i have replaced the fuel filter (z32), replaced the fuel pump, and even swapped injectors with a friend (stock 370's) and still the same problem. I've readjusted the TPS, checked the coolant temp sensor, cleaned the MAF and check for boost leaks with a leakdown tool. and still have the same problem.

the only other thing i can think of is that i may be maxing out the MAF. but that seems kind of unlikely at only 10psi, plus that wouldn't explain why the car runs like poop on 36psi of fuel pressure. I've also double checked my boost gauge and fuel pressure gauge with known good gauges so i know that they are right. this is becoming very frustrating!

any help will be greatly appreciated!

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Steve-O

1GayDrifter

you are royaly fked....


re-adjust that fpr before it gets worse. let more gas flow than air

clark

how is your timing?

are you sure your plugs are gapped correctly?

was the fuel pump new when you installed it?

what fuel are you using? how long was the fuel sitting?

what are your tps settings?-

how do you know your boost is 10PSI? how do you adjust boost?

you have basically the same setup as me, but i don't even have an adj FPR and i run great.

1GayDrifter

a car can run lean if the spark plugs arent gapped correctly? hahahaha

Spoolpigeon

plugs gapped at .028

tps set at .45 volts closed

had a 300zxTT pump in it, just swapped in a friends brand new 255 pump

HKS wastegate to adjust boost, and checking it with a boost gauge silly

and running good ol' 93 octain


everything seems fine, just runs lean at WOT. i'm thinking about just cranking the shit out of the fuel pressure

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Steve-O

1GayDrifter

be careful though you dont want it too rich. use process by elimination in a way. just turn the knob little by little till it gets to normal

Spoolpigeon

yeah, i've been bumping up the fuel pressure a little bit at a time. once i get to the 60 psi range the car starts missing at idle and sputtering at partial throttle. once it cools off i'm gonna go check for vacuum and boost leaks again.

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Steve-O

Spoolpigeon

ok, i checked the voltage going to the pump. it was oly about 11.5 volts were the battery was 12.6. so i did a rewire on it and still the same results.... i'm pretty stumped

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Steve-O

clark

i don't recall coming to any conclusions like that in my post.

it's called deduction.

OP, how's the ignition timing?

your setup doesn't seem to be anything that would require a tune, but your symptoms basically indicate you need a tune.

generally, increasing fuel pressure by itself isn't a good way.

i mean, temporarily you can look into an AFC to fool your MAF until you get the proper tune, actually, now that i think about it, test your MAF. there is a procedure in the FSM.

ideally it'd be nice if you had one you can swap with a friend or a local who has an SR or a SOHC KA24E engine.

Spoolpigeon

i checked the timing again, stock 15 degrees BTC. I'll look into checking the MAF. and my next step is to swipe teh maf and ecu from a friends sr car.

i know it needs a tune, even though it's not a crazy set up or anything. the next big purchase will be nistune. then i can run my N62 and s15 injectors

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Steve-O

Spoolpigeon

ok, so i swapped ECU's with my friends car. and it's not the problem. we were going to swap maf's, but his has a different plug than mine. so i'm going to go to a local junkyard that has a single cam car and grab the maf from it.

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Steve-O

singlecamslam

What wideband are you using? And could it be that you skipped a tooth in the timing chain?

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Nothing says racecar like a stock car with no interior.

handinpants

i would have to say bigger injectors and a tune,

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Spoolpigeon

its an autometer wideband. and i had already double checked the cam timing too. it's right on

i ordered a consult cable today. hopefully some datalogging will help find teh problem

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Steve-O

wisDOMination

just wondering if you found the problem

hottscennessey

Bump

msg lenth