A_LSD on a dyno??

[Risking]

I have an R33 equiped with the A-LSD option. Now when its on the dyno the power curve goes up till 90Kph then drops (to 70kw) and then comes back up again.

The A-LSD and ABS lights are on and go off as soon as it off the dyno.

Obviously the car is realising the difference in wheel speeds but how have others gone around this problem?

Its driving me nuts as I cant tune the car properly till I can get a proper power pull.

Anyhelp would be great thanks.

[paulr33]

my 33 has alsd and its had a few dyno runs with no dramas. i dont see why the abs light would come on during a dyno run? does the slip or a-lsd light come on? a-lsd means system error spli means its slipping and splitting the power

[Risking]

Pretty much all of the lights come on. As soon as the car was driven off the rollers the lights went off and it was normal.

When sitting at idle on the rollers it was fine as soon as the wheels turn the lights go on.

Doing snapshots the lights were all on as well.

http://accesssupport.com.au/risking/dyno.jpeg

[Risking]

The lights are on as soon as the wheels start turning on the rollers.

Drive the car off the dyno and its all normal.

Its there during snapshots and all.

These are a series of full throttle power pulls, as you can see the radius on the bottom of the dip is the same on every run indiacting its the ecu dialing back in the power?

[paulr33]

what mods and boost are you running

[Risking]

Its basicly a series 2 R33, turbo back exhaust, pod, SAFC, Front mount and on these runs it was about 7 and 9 psi with an EBC

The power on the graph can be disrgarded as its not even at redline as the engine was obviously not going to make anymore power.

[paulr33]

hmm my first guess would have been the stock excess airflow cut from too much boost but not sure really. does the safc come up with crazy knock figure or anything that could indiciate why the ecu is backing off the timing, assuming that is the cause. do you get any smoke or loud noises or whining when its on the dyno, or you weren't there when the runs were done?

[Risking]

I was actually running the car. The car doesn't even hessitate during the flat spot it just doesnt make any power!

Everything is spot on perfect. I logged everything I could with consult and nissan data scan, (I work for a Nissan dealership) The MAF is no where near maxed, injectors are only hitting 66% give or take but the timing is dropping from 22 odd to only 6-7 in the flat spot. which is exactly what the data log does when it wheel spins on the street, just you dont seem to notice the massive power loose

It has to be A-LSD realated.

[paulr33]

well is there a fuse you can take out or disable for the a-lsd system? the consult appears to have some form of diag for the a-lsd have you tried that? or at least the service manual states it does but never covers what it is or how to do it. i have a-lsd and an aftermarket ecu and the a-lsd light comes on and indicates a-lsd fail but i dont loose any power. this is intermittent on my car and the rest works fine, even the slip mode works, just occaisioanlly the a-lsd comes on and it fails. restart of the car fixes it. so the a-lsd comes on as soon as its on the dyno and a-lsd stays on and you loose all the power. hmm odd. the power loss your seeing sounds like the stock ecu retard and protect mode from excessive airflow but i doubt you would be hitting that on stock boost, also you would see the afm max out if that was the case as well (but its not maxing out). i dont have any ideas sorry

[Sydneykid]

Ahh, traction control at work. I had heard this was a problem on the dyno, but I have never actually seen it. Maybe try pulling the ABS and A-LSD fuses. You will still get a warning light or two, but the traction control shouldn't interfer. Please let us know how you get on, this is bound to happen to someone else.

[paulr33]

did you get this sorted out?

[Risking]

Not as yet no. I have been flat out at work and not had a chance to get the car back on the dyno or play with fuses