Z31 ~2500RPM lean dump. pre/post 2500 runs great.

[axel kain]

I have been dealing with this for a few months now, talking to Matt off and on, wondering if anyone else has seen this. idle, fine, accelerating, AFR's fine, hit 2200-2600 RPM or so and it just pegs lean AFR's, stumbles, adn I hear the turbo spooling, but not accelerating, until past the RPM point (with some momentum already) and it will kick right back to proper AFR's and accelerate excellently!

I have had the ROM chip reflashed at AutoVaughn performance... to no change.

setup -
Nistune Type 1 in an 87 NA ECU.
NA-T VG30E stock internals, except for Jim Wolfe springs, and Isky cams (not too radical).
Palnet fuel rails, Evo 8 I think 560cc Low imp. running about stock psi. Walbro 255 pump.
Intercooled, running blow through MAF (tested with a PMAS (HPX Z32 spec) and with an actual Z32 MAF)


I can easily get it up and running with quick resize, and MAF correction in nistune, then set the latency and have it idle proper etc. but I can take and set all 3 rows from 2200-2800 or so from 0-10 values up to 20, 30, 40 values, and not really have an effect on the issue, still have it dump lean every time. I have logged in the past, no real information of value, as there's no real hiccup or jump, other than the AFR dumping full lean.

anyone else seen anything like this? I have my brothers and my car BOTH running great, with the same cams, Nistune, AND blow though setups. I dont understand why my friend's here is doing this!

[axel kain]

I also want to add, I am currently running the PMAS MAF from this car, on MY car with nistune with no problems what so ever.

[Matt]

Probably worthwhile posting the log and the BIN file here again, referencing the point in the log where the AFRs peg lean so I can have a look at your injection time, TP (load) and RPM to see if it is ECU related

Its been a while since emails and I lose track of things quickly

[axel kain]

Well Im going to try messing with the ignition system just for peace of mind. also since I have spare parts that are new. from the log's I have done, the TP, RPM, MAF, Injection % etc are all pretty linear during the issue.