Weird R32gtr/dyno Problem

[rb180]

So i took my r32gtr down today to get a power fc and boost controller installed and tuned. Mods are full exhaust, hks intakes, splitfire coil packs, adj cam gears and thats pretty much it. Now the power/power fc boost controller is installed and the car is put up ontop the dyno. The cars put into gear and the clutch is let out and the car stars to accelerate but rear wheels are being help back by something so the torque is sent thru to the front wheels while the back wheels are being help back, almost as if the rear brakes are being applied.

So what they did was stop the car and run it in RWD mode by flicking the switch i have rigged up to the fuse under the dash. The car does the same thing but now without transferring any torque to the front wheels as the switch is flicked over 2 RWD mode. So its as if the brakes are being applied when any speed is gained.

Next what they did was replace the stock ecu which also had the same result in both RWD and 4WD modes.

So they decided to take the car for a spin around the block to see if the same thing happens. The result was the car driving perfectly fine in 4wd mode (Torque was being applied to the front as usual) and also in RWD mode(No front torque transferred).

Now heres the weird part. When the brakes on the dyno are turned off(load is applied to the rollers by a brake to measure the power output of the car like you all know a dyno does) the car drives fine and can accelerate normally.

So just in summary the problem is I cant get the power FC tuned because the rear wheels are being help back by something when you try to accelerate on the dyno in both RWD and 4WD modes. When the car is put back on the road it drives normally in both RWD and 4WD modes with both ecu's in.

Could it possibly be a fault in the dyno brakes? I cant think of anything else that it might be.

The workshop owner has never seen anything like this he said and neither have I ? Any help or idea's would be great.

[GeeTR]

I'm not 100% of your issue. But keep in mind when you go to 2WD, you generally pull a relay which controls both ATTESSA and ABS. If you have hooked up your switch incorrectly, then its turning ATTESSA off only.... resulting in the ABS kicking in when the rear turn and the front don't...

Could this be your issue?

As a test, switch to 2WD and then on the street, induce some wheelspin. If the ABS kicks in, my suggesiton is correct.

Edited January 21, 2008 by GeeTR

[TTT]

did the dyno guy try a different car on the dyno?

Has he tried to reboot the dyno?

[rb180]

thanks for the replys. Im pretty sure its hooked up right as when i switch to 2wd mode and induce some wheelspin on the street the abs doesnt kick in. I have one of those garage switches off the forums here. Also the anti-lock light comes on with the 4wd light when the switch is flicked.

The guy said other cars are on the dyno are fine. But he did just give me a call and said he talked to his friend who had the same problem and he did reset something. So im taking it down now and ill see how i go.

cheers

[blind_elk]

First of all, the phrase is "held back" (not "help back").

The dyno is the only common element to the (bad) behaviour. Then it has to be the dyno.

[TTT]

CTRL, ALT, DEL on the dyno.

[rb180]

All was sorted. He reset something on the dyno, I'm not sure what it was and then it worked fine after that

I managed 244 kw at 1 bar. Car is stock apart from full exhaust, hks intakes, splitfire coil packs, adj cam gears and an exedy clutch. I'm pretty happy with the result. I'm also hitting Calder park this Friday to see what 1/4 mile time i can get. I'll try and post the dyno sheet up to see what you guys think about the graph. Cheers

[TTT]

My guess is 12.4-12.6 for your run.

[rb180]

I've already ran a 12.5 before the mods were on hehe so im hoping to beat that at least.

[jenkies]

your killin me lol i got similar mods and only made 200 awkw and 625 nm of torque. how much torque u make?? and can anyone tell my why i only made 200?? car is in awesome condition and running high boost of 1 bar

Edited January 23, 2008 by jenkies

[TTT]

different dyno = different figure.

torque from the dyno is not the same as torque quoted by manufacturer.

Dyno is a tuning tool.

Drag strip shows car's ability.

[Beer Baron]

I'm not 100% of your issue. But keep in mind when you go to 2WD, you generally pull a relay which controls both ATTESSA and ABS. If you have hooked up your switch incorrectly, then its turning ATTESSA off only.... resulting in the ABS kicking in when the rear turn and the front don't...

Could this be your issue?

As a test, switch to 2WD and then on the street, induce some wheelspin. If the ABS kicks in, my suggesiton is correct.

that's unpossible. ABS releases brake pressure when you lock wheels under braking. it doesn't apply the brakes all by itself.

also, the cabin fuse is the ABS sensor fuse so it cannot just disable ABS, or just ATTESA. there is a fuse in the engine bay that can independently disable ATTESA but leave ABS alone but most people are too lazy to go for that one and just use the cabin one.

anyway, problems solved - faulty dyno.

[Adz]

Mate if your bloke doesnt know how to setup his dyno I wouldnt let him any where near a PFC.

PFC isnt just plug and play you really need to know what your doing. A PFC can be the best modd to blow up your motor the quickest, youl need "help back" to another workshop.

can i ask where you took it to?

[rb180]

I'm pretty sure he knows what he's doing. He tunes cars all around the world i was told by some other people. And the car is running perfect atm so im very happy with the work. His name is Ray and the shop is now called ART in heidelberg.

[GeeTR]

that's unpossible. ABS releases brake pressure when you lock wheels under braking. it doesn't apply the brakes all by itself.

also, the cabin fuse is the ABS sensor fuse so it cannot just disable ABS, or just ATTESA. there is a fuse in the engine bay that can independently disable ATTESA but leave ABS alone but most people are too lazy to go for that one and just use the cabin one.

anyway, problems solved - faulty dyno.

Hah - v.good point bout release not apply! ma baddness