RB25 + custom 880cc injectors = terrible cruise and idle

[ar99kid]

1. in the past did have a sort of problem like this , also on rb25 but with 300zx ecu. try to clean the electric idle control valve in the back of intake plenum. if that is clogged and don't open how it suppose to , it will be very rich at idle ...

2. also check the TPS voltage settings in nistune and voltage output when idle from TPS and see if the ECU is seeing idle from the TPS .

3. VTC settings same as TPS ...voltage and RPM when cut in /off... if you have higher idle RPM you need to look at those VTC RPM settings...

might work...

[dark_180]

Hey mate where is your airflow meter if its on the front of the turbo, the turbo palsats under light load which courese it to over fuel. That was what my car did, i landed up puting a 90 bend in, since then i have not had the problem.

[bachig24u]

did the log of MAF voltage demonstrate the pulsation?

[dark_180]

No it did not the only thing was everyknow and then it showed a massive spike like 235v which I thought the tracker was wrong because your afm does not work on 235v

[Nissanclubman]

I was working with a mate on exactly the same problem and did the same as everyone has done. Replaced MAF, ECU, Injectors, K constant, Injector Latancy and massive changes to the fuue map, tested fuel presure, fuel regulator etc but nothing worked.

We even had an identical setup (Different car however) and still couldn't figure out what was different. The only thing we found was the position of the MAF in relation to the turbo input.

So we repositioned the MAF (lengthend the pipe from the turbo to the MAF from 300mm to 700mm and FANTASTIC.. problem solved..

The real strange thing was we couldn't see anything odd with the MAF signal or injector PW etc. I still don't know why it solve the problem so to test it we shortend the MAF deliver tube and the problem came back. Lengthed it again and the problem dissapeared.. Hope this helps.

[Matt]

The extra length may be just enough to stop any excess reverse airflow from going through? PL has noticed massive differences just with the air filter installed when dynoing an RB25DET NEO

[PL]

I did an SR last week with an HKS GT3037 Pro S and I fear it's suffering a similar problem. Z32 AFM about 300mm from compressor mouth. Suffers poor return to idle and general bad manners at low load. I logged it to death and I can see no anomalies in the AFM signal. Not sure how we'll fix it at this stage...

PL

[TM_S13]

the z32 afm is known for not responding well when fitted too close to the turbo mouth...
one of the options is to add a bend between... I've seen it happening and that solved the issue...

[PL]

Yeah, I've had plenty of trouble with them before - often solved by just changing the plumbing...

PL