R32 Gtr With A Lack Of Power!

[Berry]

Hi guys,

Sorry for this being my 1st post, but thought someone maybe able to help out of this one.

I've had my 32 for over a year now and had some issues but some great times. It pulls well and i thought was full of power for a low tuned example (spec below). Anyways thought it was time to get a health check and power run to see how things were.

Engine spec

RB26 with std internals (as far as I know)

Std ecu

Std boost

Driftworks wasted spark plug kit

Up rated plugs

HKS twin filters

De-cat

Apexi (Jasma) exhaust

Went to a very well known company who deal with a lot of race car tuning etc. and was expecting 300-330 hp.

But got 230bhp!!!! @ 5200 (power just fell off! and 466 lbf.ft of torque! (which seems very high!)

The graph

The guys said it looks like the its getting 'strangled' top end and they suspect its the exhaust...they have found that Jasma spec exhausts can cause major restrictions. So have replaced exhaust with a Japspeed hi flow cat back system.....but no change! (Altho it seems a little easyer to drive!)

The cars also seems to be idling very high (around 1600 rpm) had a hunt for vacuum leaks etc with no results! Have also played with idle control valve and AAC, disconnecting both with no change!

So my question is.....um what’s going on lol...have i got 2 problems????

Any help would be great.

Cheers

John

[Moodles2]

Find the R32 GTR service manual off the net and find out the procedure to put the ecu into diagnostic mode. Yes that torque figure is very high.

My suspicion is the Air Flow Meter.

Wouldn't hurt to reset the ECU and see if it solves the idling issue.

[Berry]

Find the R32 GTR service manual off the net and find out the procedure to put the ecu into diagnostic mode. Yes that torque figure is very high.

My suspicion is the Air Flow Meter.

Wouldn't hurt to reset the ECU and see if it solves the idling issue.

Cheers, will have a look

[__PhaseShiftDown]

high idle is probabaly caused by air leak somwhere, split vac line or bad gasket. Get a can of carby cleaner and spray it around the engine bay, especially around the intake planum, around the injectors, throttle body....etc. If there is an air leak around that area, the engine will pick up rev.

And yes, check the AFM.

[Moodles2]

Check the hoses to the charcoal canister, mine kept blowing off and it would idle high, i ended up using hoseclamps to get them on.

[Godzilla32]

High idle:-

The only hoses on the charcoal canister that will cause a high idle are the vacuum signal and purge lines. They are both connected to the intake manifold and will cause a vacuum leak. Zip ties work well. Concentrate either aerostart or carby cleaner around the intake manifold area on all your pipe connections and joins. As mentioned if you hear a rise in idle speed you have a leak there.

If its possible to get to you could carefully try crimping the hose to and from the air regulator (cold start), and Idle control valve. Once warm there should be a difference crimping the hose from the air regulator as it should already be closed. If you can crimp the hose from the IAC and the engine continues to run then you have an air leak. The IAC is an air bypass valve to control the idle speed. No air will pass the throttle butterflies at idle, as they should be completely sealed shut. The engine completely draws its idle air intake through the IAC. Keep in mind if the hoses are old and hard they will crack if you crimp them too much.

I personally have had issues with leaking throttle butterflies creating a high idle, and i know of a few others too.

Lacking power:-

Checking the ecu for trouble codes is a good idea to possibly point you in the right direction. I suggest checking them then unplugging your battery (wait a few seconds) to reset the ecu and also delete the trouble codes. From there take notice how the car idles and take it for a drive then recheck the trouble codes to see if the same ones have returned.

You can check the AFM's for voltage by back feeding into the AFM plugs (one at a time). Cranking voltage should be 1v, idling 1.1v, however the most important one to check is full load. Take the car for a drive and at full load you should see upto 4-4.5v If its not then you have an issue and need to replace one or both AFM's.

Have you checked that the CAT isnt blocked or damaged? A CAT back system is only as good as the CAT in front of it. Same goes for dumps and front pipes, etc.

Did you get a graph with AFR readings? This is very important to see if the car is running the right mixture.

Make sure the car isnt actually misfiring at high RPM.

Check your air filters for cleanliness as a restriction here will cause issues.

I've noticed there is some boost creep on the graph but up top it only reaches 7.5psi. It should be there from the start after the turbos have spooled up. This could have been a result of the other exhaust. You should re dyno it and see if there if much change.

Hope this helps,

Deren

P.S:- A dead stock R32 GTR will make around 220rwhp so you may not be too far off power figures.

Edited May 8, 2009 by Godzilla32

[Berry]

Cheers for the replys, very good info.

Gunna check voltage at afms this weekend.

Have a de-cat pipe on there, inspected the front pipes as best as i could when they are on the car, and have new HKS filters.

The car is running better since changing the exhaust etc.

Will see what i can find out over the weekend

Cheers

John