Low Rpm, High Load Miss

[Marcus89]

My r34 GTT has decided to develop a miss under 2k rpm but only when warm and only when under load (2nd gear with large amount of throttle will do it, 3rd and 4th gear is much worst).

There are no error lights on the dash and car works perfectly while still warming up issue only begins once at operating temperature.

I also have no problems at higher revs at all comes on boost well and revs throughout without any problems.

I am stumped as to what could be causing this.Have had a look around to see if anything seems to be out of place (have changed the turbo a fair while back now) but don't see any obvious problems.

Anyone got any ideas as to what would cause something like this? Seems to be very specific in the parameters it needs to cause the issue

[DVS JEZ]

What setup?

Only thing im thinking thats alittle outside the box is the fuel pump wiring. If u havent rewired it maybe the low rpm (low voltage) not enough fuel

[Marcus89]

I have installed a bosch fuel pump and haven't changed the wiring from stock so I guess that is a possibility. Still seems strange to start doing it when warm but I guess it is possible the ECU drops the fuel pump voltage when no longer in cold start due to needing less fuel?

I have basic stuff installed:

Fuel pump

Atr43 turbo

FMIC

splitfire coilpacks (also have fairly new copper spark plugs in there i'd say <1000k's old)

Nistune

Most other stuff is stock ATM have got injectors that will be going in soon as well as Z32 AFM

Oh also when changed spark plugs I changed the fuel filter and air filter

[DVS JEZ]

Didnt realise it was tuned,

May be in the tune? Get it on the dyno so it can be checked

[scotty nm35]

If u havent rewired it maybe the low rpm (low voltage) not enough fuel

^^ This.

Rewire the pump through a relay and take it back for a clean up tune.

[Marcus89]

What setup?

Only thing im thinking thats alittle outside the box is the fuel pump wiring. If u havent rewired it maybe the low rpm (low voltage) not enough fuel

^^ This.

Rewire the pump through a relay and take it back for a clean up tune.

This was the problem cheers for that guys. Took it for a long drive tonight (after doing fuel pump rewire) and had zero problems all ready to be tuned up on Sunday now

[Marcus89]

Wanted to make sure I replied to this topic cause I know I hate it more than anything when I find a topic with almost the same problems and no final resolution

[DVS JEZ]

Perfect buddy. Thanks for letting us know

[scotty nm35]

Good to hear its running fine Marcus.