Gtr Issue

[MsR]

recently took my car to the tracks and noticed some issues which were not there when it was tuned about a year ago (not putting the blame on anyone here)

at idle, when you tap the throttle, it feels like the revs drop momentarily. Even when you rev the car in neutral, it feels like there is hesitation below the revs pick up. any idea what this is?

also at wide open throttle (WOT) the top of 3 gear is splattering. is this lack of spark? i have a big fuel system in the car and on the dyno it was fine, but im sure real life situations are different to dyno.

and last thing is at wakefield, as i come in fast to a corner and brake (turn 2, fish hook and last corner) the car doesn't rev or do anything! it drops to neautral for about 2-4seconds then picks back up again. I've tried to rev match and downshift but nothing worked! Car drives on the street fine but this is concerning me.

Is it a Tune? Spark? Fuel?

[portaz]

Sounds like fuel surge on corners , but u have bit fuel system , changed filter in last year? I'd be checking fuel pressure and also all fuel related electrical connections , sputtering up top happened to me recently and was a boost leak I didn't know about , if all if above ok I'd look at earthing coils directly before looking at tune,but you could contact your tuner usually they are more than happy to hp if they are any good lol

[MrStabby]

Simplest thing to start with for the 3rd gear splatter is to pull the plugs and take a look. Change them anyway if they're old. Don't run a wider gap.

Also, tunes don't last forever because all the components that produce power wear/get dirty etc and don't behave exactly like they did when the tune was done.

Agree that fuel surge is the last issue. As soon as that happens head off the track and back to Goulburn to fill up again, or take spare fuel and save the trip. You'll find it starts at about the same fuel tank level each time.

[Blackkers]

When you say a big fuel system do you have a surge tank?

Also do you have a wideband? That would tell you pretty quickly if you've got a fuel supply issue. I'd be worried at the top of 3rd gear if it's starving for fuel.

[Badgaz]

i'm gonna make some guesses here.... you need to do this

i did this on my wifes GTR that had a missfire when up it in third. the second part might be that your tuner may not have done your accelerator correction, or it could be your TPS. make sure your tps is reading the correct voltage at idle i think its 0.45v-0.55v at throttle closed position, the voltage should increase to somewhere between 3-5v at WOT. you don't need to do this with the car going but just the ignition turned on.

whats your ECU ? can you datalog?

[MsR]

shall be cleaning the fuel filters out this coming week. plugs checked out ok and did a quick compression test as well and engine seems good. strange why it would be spluttering down the straight if it was surging as that is what i would expect from cornering

fuel system consists of a Weldon 2015A fuel pump, Earls billet fuel filters, -8 lines to the surge tank, -8 hose all the way up to the engine then splitting up to 2x -6 at the fuel rail

[Badgaz]

whats your spark plug gap? and what coils are you running? are you running stock mafs?