Help on my rb25det :(

[mando240]

Hi guys well here is the info :)
Rb25det S2 fully rebuilt
Isis Manifold
Q45 Throttle
STOCK MAF
STOCK INJECTORS
STOCK ECU.

THINGS I CHANGED
I PUT A NEW O2 SENSOR.
Q45 HAS A GOOD TOP SET AT .50 VOLTS CLOSED
VACUUM IS GREAT LEAKS

The problem starts when the car warms up. It starts TIPPING!!!
Cold start car drives good i go trough gears no problem (NOT WOT) all of this is driving normal. Once it reaches O/T if i tap the throttle the car LEANS OUT LIKE HITS A WALL and it clears up and goes. Like this lol bear with me
1st gear ease of the clutch and go good, i go into second gear and hit the gas pedal (BOOOOOM LEAN) and let go clears up... only when i tap the throttle to the gears or if im cruising at 40mph and i suddenly have to accelerate to over pass i cant just give it gas i have to ease it in if not (BOOOOM LEAN)..

SO in other words if i ease in the throttle its fine but if i tap/smash the throttle is hits a wall LEAN SPOT MASSIVE TO.... WTF :bash: this has been driving me nuts... anyone plz :)

[User_Name]

Hi guys well here is the info :)
Rb25det S2 fully rebuilt
Isis Manifold
Q45 Throttle
STOCK MAF
STOCK INJECTORS
STOCK ECU.

THINGS I CHANGED
I PUT A NEW O2 SENSOR.
Q45 HAS A GOOD TOP SET AT .50 VOLTS CLOSED
VACUUM IS GREAT LEAKS

The problem starts when the car warms up. It starts TIPPING!!!
Cold start car drives good i go trough gears no problem (NOT WOT) all of this is driving normal. Once it reaches O/T if i tap the throttle the car LEANS OUT LIKE HITS A WALL and it clears up and goes. Like this lol bear with me
1st gear ease of the clutch and go good, i go into second gear and hit the gas pedal (BOOOOOM LEAN) and let go clears up... only when i tap the throttle to the gears or if im cruising at 40mph and i suddenly have to accelerate to over pass i cant just give it gas i have to ease it in if not (BOOOOM LEAN)..

SO in other words if i ease in the throttle its fine but if i tap/smash the throttle is hits a wall LEAN SPOT MASSIVE TO.... WTF :bash: this has been driving me nuts... anyone plz :)


Have you changed your fuel pump? I had this problem prior to changing my fuel pump. Also a good idea to change the fuel filter as well. A 300zx TT fuel filter is fine.

[mando240]

Have you changed your fuel pump? I had this problem prior to changing my fuel pump. Also a good idea to change the fuel filter as well. A 300zx TT fuel filter is fine.

i have a walbro 255 and a 300zx fuel filter i havent changed the fuel fuel pump to a newer one cause its troughing good psi..

[User_Name]

i have a walbro 255 and a 300zx fuel filter i havent changed the fuel fuel pump to a newer one cause its troughing good psi..

Have you recently changed the spark plugs? What Gap are you running?

[mando240]

Have you recently changed the spark plugs? What Gap are you running?

im changing them today after work ill post up :)

[username]

Make sure the q45 throttle plate is actually all the way closed. I had a similar problem and it was the idle adjustment screw had loosened and cracked the throttle body open a little bit.

[User_Name]

im changing them today after work ill post up :)

Make sure to GAP them correctly or you'll have a bad misfiring problem pretty much feeling like you're slamming into a wall @ WOT.

Report back and let us know!

[redline racer510]

I also read on this forum and a number of others that the stock fpr can cause abnormal fuel pressure fluctuations that can cause your engine to behave like it is getting too much fuel or not enough. What I am going to do is buy the aeromotive fpr kit from raw brokerage to resolve this. Do some research and see for yourself.

[User_Name]

I also read on this forum and a number of others that the stock fpr can cause abnormal fuel pressure fluctuations that can cause your engine to behave like it is getting too much fuel or not enough. What I am going to do is buy the aeromotive fpr kit from raw brokerage to resolve this. Do some research and see for yourself.


This is what i have on my RB. It is working out fantastic for me, tho i don't know if it is the OP's problem, worth a try right?!

[redline racer510]

i would rigg up a fuel pressure gauge and see what happens when you lose power

[mando240]

i have an aeromotive FPR also with vacumm i have it set at 37-40 psi

[mando240]

i would rigg up a fuel pressure gauge and see what happens when you lose power

thats what iam thinking cause the wide band goes super lean... unless is the injectors cause i have an ebay 50trim turbo but at 7psi??? should not be leaning out the car so fast.