Nistune Forums

R34 Neo rb25det
Basically stock just cooler and exhaust.
Previous tuner said its leaning out due to fuel pump so customer put in a walbro, then had driving issues so he came to me.

I have rewired the fuel pump to recieve full battery voltage.
Then road tuned. Was goin good at 1st but then it leans out hard from 4000 onwards.
So we checked everything over and tested again. Same thing.
Went and filled the fuel tank to full from half. Reloaded the last tuners tune thinking maybe i missed a setting some where. Retested and no longer leans out. So i retuned it and it was ok. (This here made me think it was my tune, but after today im thinkin it might be fuel flow related)
2weeks later customer wants to push some more power into it.
So today i connected everything up and went for a drive. Without touching the tune its leaning out again. Try to add heaps of fuel and it runs 10.8 till around 3750ish RPM where it leans out to 14 by 5000rpm.
I have checked TTP MAX and TP CUT etc and tried raising them.
Is there something i have missed?
I will load log file soon but my innovate isnt connecting to nistune at the moment(nistune 14.22 crashes) and the bin file of todays little tune and the last tune.

Oh i have even loaded the stock base map from the rom pack and only adjusted limits and load tables and it still leans out the same.

I think the fuel pump is a dud or the fitment of the fuel pump is incorrect. Couldnt try it with a full tank today.

Please help

and this is todays quick tune with mainly limits and load tables modified

Have you tried cleaning / swapping the AFM. It it doesnt read properly wont put in enough enrichment

I have not tried. The biggest issue is he brings the car from sydney 1hr to me. And cant leave it here as he uses it as a daily.
If it was the afm could the issue be that consistent?
I will try it next time.
Can u see any issues in the log or bins?

Certainly sounds like a fuel pressure issue. Could also be dirty AFM as Matt said but my money would be on fuel pressure.

Having a WB AFR meter in the car would give the owner an idea of what's going on (and when to back off cos mixtures are leaning out). At $US200 those new Innovate MTX gauges should find a home in every modified turbo car I reckon...

PL

perhaps a faulty FPR (or split hose to the FPR) ?

had a similar issue on a Z32 once...turned out to be the FPR

Thanks for the replys.
As soon as i can get it on the dyno on a saturday i will connect the fuel flow/ pressure tester. Which my dyno operator has.
Abit scary using them on the road.

Its a brand new walbro. Very dissapointing if it is the issue.

R34 neo seems to have 2 pressure regs and a dampner. Does this sound correct

2 dampers, 1 pressure reg.

Hmmmm. This caught me once before and now I can't remember which was which. From memory the best way is to just follow the fuel rail and the reg is the one that the front end of the fuel rail feeds into (as you'd expect...).

Or I guess you could look it up in the service manual...

PL

OK, just checked the manual. FPR is the one nearest the engine (the one that's harder to get to...).

The one near the front of the manifold is just there to confuse us - it's only a damper.

PL

Haha yeh nissan engineers put 2 dampners there that look like regs to play with our minds

Wouldn't the FPR be the only one with a manifold signal hose running to it though?

They sure look the same on the RB20's also, managed to gut it, silver solder it back together and use it for a fuel rail adapter.