AAC VALVE QUESTION... STARTING PROBLEM

[USMCgetsome]

Ok. Here's what i got.

89 240sx HATCHBACK/RB25DET

all 6 spark plugs firenew walbro 255lph pump installed todaynew nismo fpr6 fuel injectors check good for pulse from the ecu and ground... do not for sure if they work mechanicly.

I can get the engine to start with a lil starter fluid then i can throttle it fully for a few heavy pumps then it dies.

I reffered to the FST and it tells me to check the AAC VALVE but in my FST it does not show where it is or how to adjust.

ANY SUGGESTIONS OR COMMENTS???????

Thank you for reading this post!SGT FLO

[Ramius83]

Since you have the NISMO FPR installed, what is your base idle fuel pressure set at? If you do NOT have a Fuel pressure gauge installed, that is your first priority.

[Ramius83]

BTW, to check the AAC, it is located underneath the intake manifold, on the 240sx passenger side. (Atleast, that is where it is on the RB26). It is labeled with a gold/black tag that says AAC Valve on it. Usually has two harnesses going to it.

[USMCgetsome]

The fuel pressure gauge is on its way; and your right, i do not know what the pressure is. I also found the aac valve and it read 10.8ohm soo it's good.

ANOTHER QUESTION.

there is a green stem valve on the left hand side of the engine (looking at the engine from outside the car) nothing connected to it. is there supposed to be something there? i'll have pics by tomorrow.

[JonPowell]

Green stem valve is not a valve at all, but a knock sensor. You are looking for something BOLTED to the intake manifold on the underside. It has 2 rubber air hoses going to it.

If you are have trouble starting the car...did you check the start signal going to the ECU?

Orange on the car side..in the brown or white plug clipped to the dash reinforcement above the ECU and grey/red on the ECU side.

This sends a signal to the ECU that you are cranking the engine and fattens the fuel maps & adjust timing to make starting easier.

[accel junky]

Sounds almost EXACTLY like my problem.

I thought you guys said that the start signal wire wasn't orange necessarily for the s13, but for the s14.

[JonPowell]

I will post pics of the plug on the car side later tonight. In S13 it IS ORANGE. On RB harness side its grey/red.

[USMCgetsome]

OK fellas i recieved and installed the fuel pressure gauge today..

i read 40psi when the pump comes on then 45 when i crank. I'm gonna turn down the pressure to 36psi and then start from there. The start signal from the ecu GREY/RED wire to that harness is different on mine. I checked the orange wire and there is no signal coming from that plug. But there is another wire on that plug that i tapped into and it gets 12vdc switched from the (KEY STARTER).

Would it help if i sent that wire to the ign relay and just got my signal from there?

[USMCgetsome]

WTF..... My grounds went to sh*t. I check all my ecu grounds and they read about 10-40ohm. where the hell do they share thier grounds? i see that they tie up to the funny brown plug with the main harness. where do they go from there? besides all that i checked for signal and voltages through all the pins on the ecu and they all check good soo far. All fuel injectors get the 12vdc and pulse from ecu. Umm... And the starter signal pin 43 Grey/red wire i jumped it to the ign relay and my cluster lights go out when i turn the car on and off. You guys should try that. Because, when i had it going to that white/brown (which every S13-S14) i used to have to pull my 75amp fuse to get it to shut off. I put it to the ign relay and it shuts off when my turbo timer goes off. EVERYTIME.. NOT OCASSIONALLY WHEN IT WANTED TO.

Also, i found the a plug to the green valve stem (knock sensor) it's an oval connector with a female pin in the center.. Correct or not? i looked for the hoses bolted on the bottom of the throttle body and didn't see the hoses that you were talkin bout jon. THANKS for the help soo far.

[USMCgetsome]

still no love soo far. engine starter with starter fluid and i check fuel pressure and set it at 36psi with the fpr. I get 2 -3 good high revs in and then the engine shuts off automatically. and i mean throttle or no throttle. turbo spins and winds down. may be a vaccum leak but i i don't see any hoses disconnected don't know what else to look for.

[JonPowell]

STOP!Set fuel pressure to 43PSI with the vacuum line off...wherever it sits after that is PERFECT. if its 36, 32, 38...doesnt matter. You set the base fuel pressure & let the vacuum line adjust from there.

Grounds are on the intake mani near the temp sensors. Check the LARGE ground strap from your battery to chassis to block.

Is your RB25 series one or series two?

Series one you gotta get +12V to your injectors through the grey wire in the rectangular plug near the MAF & boost cut solenoids.

[USMCgetsome]

STOPPED. what vacuum line? the return line to the fuel tank?

Checked the grounds they read crappy. There are 3 main lines hooked up to the block and the main chasis ground reads 0.0ohm

RB25DET SERIES 1

And yes i get the 12v from the grey wire from the rectangular plug.

[Ramius83]

The vacuum line he is talking about is the one going to the top of the fuel pressure regulator. With that unplugged, you should be reading about 43psi of fuel.

[USMCgetsome]

ok i understand now. the one from the throttle body to the vacuum of the fpr. thanks for that detail. very appreciated.

[USMCgetsome]

ok fixed the ground problems. they all read 0.0ohms it was the screw that was reading resistance soo i replaced it and the grounds are good now.

[USMCgetsome]

HOLY SMOKES SHE STARTED BATMAN!!!!!!!!!

no starter fluid but i have to have the gas pedal at least halfway down before she dies out again. Seems to get enough air but i have a bad air leak where my bov is. Fuel pressure is there and the injectors are firing i think now my problem lies with tuning out the engine. i'm also going through all my ic piping to check for air leaks.

She starts by herself no starter fluid. woo hoo.

I'd push further but my damn battery is dying soo i'm charging it up currently. should be done in 6-8 hours.

Thanks for all the help fellas!!!!!!!!!!!!!

[JonPowell]

Congrats, good to hear!!!