Flat Spot At 3000 Rpm

[adrnln]

Hi all

I am getting a flat spot at 3000rpm I release throttle and step on it again and it revs through it. It's all the time not on off. I have done the usual checks.

Any one have any thoughts??

Billy

[base308]

Dodgy tps streched throttle cable 2 first thoughts that pop into my head

[Galois]

Any other symptoms? Misfiring? Maybe it needs a clean of afm or a tune?

[toffy]

is it blowing any smoke? (i.e black) , i had an r33 do that to me , just before the fuel pump died

[adrnln]

Pump just replaced, no smoke. Will be getting looked over this weak for tune. It spits and farts when it hits 3000 rpm. I will give the afm a clean again. Thrilled doesn't stick when I free rev.

[Dose Pipe Sutututu]

All I can think of is, dirty AFM and also injectors need a good service.

[89CAL]

How much boost and what ecu?

[adrnln]

16psi and NISTune.

I changed plugs cleaned afm and still nothing. I'm going to try change the z32 afm and see if it's that also.

[adrnln]

Have found that it was low volts to the fuel pump have rectified goes like a dream now.

[adrnln]

Ok it did run like a dream now I'm having the same issue and I have changed about everything I can think of tps, afm, coils, spark plugs,injector clean, fuel pump, fuel filter. It ran fine on the dyno and when I took it to the track and it fully warmed up it start getting a flat spot and surge at 3000rpm and thing else I can try??

[DVS JEZ]

Get your tuner to put a wideband on it and go for a road tune quickly. It will be a small lean spot in the boost transition area

[adrnln]

Is the wide band what they usually use on the dyno? As the fuel line is perfect on the dyno run. I can hold the throttle flat and it will hold revs at 3000rpm until I pump the throttle through the flat spot.

[DVS JEZ]

Yes thats a wideband. Rather than strapping it onto the dyno u can replicate the issue on the road. Will then be able to to see if its a lean spot or not.

Now that u say it wont rev past it at all its a bit of a weird one. Can u drive past 3k on light to medium throttle?

Did u do a rewire on the fuel pump?

[adrnln]

Yea can drive through it in on light throttle. Fuel pump has now got a direct power supply from the battery in the boot.

Would the CAS (crank angle ) give this sort of issue?? It's the only thing I have yet to replace?

[DVS JEZ]

What ecu

[adrnln]

Stock ecu with nistune

[boostn0199]

I would chack the cas ive been having similar problems with light throttle misses at about 3000 and its the cas playn up. Cost me 50 kw aswell

[rondofj]

Gosh and i thought RBs were great reliable motors..hope u find the solution soon mate, dont forget to let us know the issue

[STATUS]

Ok it did run like a dream now I'm having the same issue and I have changed about everything I can think of tps, afm, coils, spark plugs,injector clean, fuel pump, fuel filter. It ran fine on the dyno and when I took it to the track and it fully warmed up it start getting a flat spot and surge at 3000rpm and thing else I can try??

is it a a31 by any chance? if it is bin the ecu, swap in a r32 ecu the a31 and c33 ecu's are junk and a re well known to do this.

[STATUS]

any updates?