flat spot

[twoquik]

Hey guys,

well as some of you know i have been having a few problems with my car lately,

slowly getting it sorted out, its running a little better than before the only thing wrong now is from standing still and lauching full throttle i get a flat spot after 4000rpm and continues until i change gear but i will get it in 2 and 3rd gear also.

what could it be?

[GunMetalR33]

1) Could be stock ecu boost cut. How much boost are you running?

2) Thats about the time the VVT comes in, So big touque increase which means your spark could be a little weak at that point. What have you set your spark gap to, what is the heat range of your plugs? Try lowwering the gap by 1 mil.

3) There could be a air leak in your intake piping somewhere?

[twoquik]

running 12 pound

have plugs gapped to .8, could it also be the wrong heat range, i cant remember which one

i have i think 6 or 7.

I have never had a problem with ecu boost cut before, what is VVT and what can be done about it?

[Zahos]

1 - you are definately running too rich at that RPM due to your increase in boost. The standard ECU does this. Subsequently, timing is pulled when your car runs this rich and you will get that dreaded flat spot / misfire from ~4000rpm up to ~6000 rpm. 6000rpm - 7000rpm it feels fine, doesn't it?

(search for: misfire boost SAFC hesitation)

2 - You could have some small cracks in your coil packs, causing your spark to jump around there. This ma or MAY NOT be a problem for you...

see this thread for the solution.

The first has been covered HEAPS, as just about every R33 driver has experienced this at some stage, so you should find lots of info...

You will definately need some sort of aftermarket management - PFC OR a piggy back to correct your A/F ratios - SAFC. These 2 are the most common choices, I went for the SAFC as I could not afford the combined price of a PFC and tuning that went along with it. The SAFC II (with installation and tuning) cost about $600 - $650 all up and fixed the problem for me.

Zahos

[Col-GTSX]

Go the fc...

I found the SAFC to do the job however the difference inbetween price/effort and outcome. The fc does it everytime.

I mean its worth saving the bickies to go the fc for future mods and cost saving in fuel has paid the difference within 6 months...

[The Mafia]

another vote for the powerFC.

If you decrease your boost to 11psi, and make sure it doesn't go any higher with with spikes etc, the standard ecu will run great.

BUt yeah, I have a powerc, and I'm running a brilliant tune.

[R31Nismoid]

this is over a year old.

come on guys!