Ecu Limiter Turning On At 2000Rpm

[pkiss01]

i have an 88’ r31 thats on duel fuel and recently when i change over to petrol the car wont get out of first gear and limits at 2000rpm on gas the car runs like a dream. i don’t think its an injector coz’ its not missing maybe it’s fuel starvation? fuel pump is kinda loud and changed the fuel filter not long ago its got me really stumped.

[kitto]

Air Flow Meter most likely.

Check its connected still.

If it is try cleaning the internals and the connections with electrical cleaner.

[niZmO_Man]

AFM. Change it. I'm guessing backfire blew the wires out.

[pkiss01]

just pulled it out looks pretty shot ill replace it and see what happens. thanks guys

[Traah221]

If your AFM looks good, check it with a multimeter at the plug. You should have:

Black/White - 12V

Black/Silver Tag - Ground

White - Ground

Black - This is your Signal wire to the ECU, check the continuity of it back to Pin 27 on the ECU.

If you read the post right above yours in General Maintenance, I was having the exact same issue, not with switching over to petrol, but running it all the time. I even have a video showing my 2000 RPM limit. I have a list of everything I switched over trying to fix the issue, but what it ended up being was my AFM Signal wire was grounding out with one of my grounding wires in the protective sleeve they have going back to the loom. A Continuity check found this, and I bypassed the fried wire for the signal straight to the ECU. Runs like a dream now. No signal from the MAF causes your ECU to run in Limp mode, I'd imagine, which limits it out at 2000 RPM for the engine's safety.

Good luck to you!