what's wrong with acceleration?

[R34GTT]

something constantly happen to my RB20DET.....
i notice it when i going up hill and gun it.......the turbo kicked in, sounds loud, and kept pumpin air in to the engine....but i don't feel my car is accelerating as suppose to...feels like misfiring and lost power but not. my A/F ratio @ gauge pike up and stays @ 20.0 until i let go of the gas, then it goes back normal.

this is so weird....can anyone tell me what's wrong with my car?

[DarkCaporaL]

20!? as in way lean 20?....yikes

[amnash]

ya that sounds very lean, isnt about 14-15 to 1 ideal?

[DarkCaporaL]

Idle AFRs should be around 14.7:1

WOT AFRs should be around 11.3:1

To the OP I would suggest not to go WOT if you're hitting 20 AFR.

Does it only do it when going up hill !???

[Skym]

20 A/F ratio is crazy lean and would be looking at wiring to fuelpump, fuelpump (including sock filter on fuelpump), fuelfilter in engine bay, TPS, AFM, etc (anything that effects how much fuel is injected into engine). Sometimes you find the fuel filter in engine bay is clogged as 1st owner or owners after them never replaced it. Then fuelpump might fail because of it.

Also check fuel pressure with fuel pressure gauge that's plumbed inbetween fuel filter, fuel rail when engine is idling (or on dyno if only under full throttle) which can help to diagnose the problem.

[R34GTT]

uum....so u guys think it is insufficient of fuel supply?...
i have changed fuel filter....
anyone know wut should the fuel pressure between the pump and the filter and from filter to the rail?

[feyd182]

From what I remember, at idle you should be around 45psi. As you increase throttle, I think it rises to approx 50 psi at WOT. Our cars require a rising rate fuel regulator if I'm not mistaken. I used to have a Sard regulator on my old 89 GTST and it worked perfectly. It did however require some modding of the fuel rail connection to make it work.

[Skym]

It could be lack of fuel supply or there's a leak in exhaust system before wideband (more oxygen entering exhaust system that wideband is picking up).

This is for RB20DET, RB26DETT

Ignition switch on 3.0 kg/cm2 x 14.2 = 42.6psi

At idle with FPR vacuum hose connected 2.5 kg/cm2 x 14.2 = 35.5psi

Idling when FPR (Fuel Pressure Regulator) vacuum hose is removed 3.0 kg/cm2 x 14.2 = 42.6psi

Not sure if RB25DET is the same, but can't be much different than a RB26 or RB20.