Rev cut? 6000 RPM in 4th gear on GTR?

[underground]

Hey All,

I have been experiencing what appears to be a rev cut with my RB26DETT motor...

I am using the RB25DET tranny in my Silvia...

The car just bogs down, like a speed cut, where it almost turns the motor off.. You get this instant thump where all power is cut to the motor...

It occurs about 7000 RPM in 3rd gear, and about 6000 RPM in 4th gear...

I'm sure it does this in all of my gears, but this is where I noticed it tonight when drag racing...

The only thing I can think of is I currently don't have any filters over my air flow meters.. The MAF's are wide open to the outside air.. All I can guess is that the MAF is sensing too much air flow and telling the motor to cut revs...

I'm just shooting in the air...

Any help is appreciated!

Chris

[cameron]

What ECU are you running ?

[N I B]

Its your speed cut not a rev limit.

[ferni]

Yeah was going to say, standard GTR ecu will speed cut at 180ish

[GTR-Ben]

What AFM's are you running, and is this a stock RB26DETT?

[japsky33]

Check your speed cut dude. If your losing your throttle for a few seconds.

BR,

JH

[underground]

It's a stock RB26DETT, does have cams, but that's it... Stock Turbo's, Stock ECU....

Stock AFM's

[ferni]

as everyones said, its a speed cut then, not rev cut

[GTR-Ben]

Yep has to be speed cut..

[awurth]

yeah the gears and rpm sounds about right to be the speed cut.

[underground]

Who all makes a speed cut defender..?

[wrxhoon]

Who all makes a speed cut defender..?

stock ecu , speed cut comes @8000 rpm in 3rd and a bit over 6000 in fourth in fifth it will be a bit over 5000 .

it cuts out when you reach about 185-190 kmh or 114-1180mph

[BNR32]

Trust and a few others make a speed cut defender for the GTR... they are expensive but worth it because they come with all the instructions, cable ties, wire connectors etc etc..

www.nengun.com sell to the states and his prices are good, you should have no problems getting one from there within 7 days direct from Japan.

Other alternative is to go with an Apexi Power FC if you have future plans for modifications, providing you have a local tuning shop that can tune a power fc.

[Duncan]

Or just get someone to remap your standard computer to remove the speed limit

[N I B]

Disconnect the speed sensor wire to see if the problem goes away.

[awurth]

As far as know (with 33's anyway because that's the only cars I've done it with) you can simply cut the wire. the wire is only really needed for idle map control on the Auto's (ie, if you let the car idle down while still rolling along the road the computer knows this)

[GTR-Ben]

Yep snip snip and no speed cut.