Is the VDI killing my power?
 

Ok, the car is a 90 ITS N/A. I was recently (five minutes ago) was running it in my driveway to test some things and noticed that the VDI never moves or actuates. When the engine is off, at idle, and high rpm, the actuator never moves the arm. According to the manual it is in the closed position. So, my assumption is that it is not working. Should I remove the actuator and wire it so that it is open all the time...any problems with my theory? I dont care about low rpm as i rarely go below 5k.

Thanks everyone....!

Wire it open.

of course, ludwig to the rescue. Yeah, that is what I decided to do, thanks again for the help my good man.

IIRC, it operates off pressure from the air pump, like the 5/6 ports, so that's probably why yours are non-functional.

I need to do the same to my track car (91 NA). Does anyone have any suggestions on the best way to wire it? Simple things like "where do you wire it from/to?" :D

Pictures are welcome.

Thanks,

-bill

Wouldn't the VDI operate the same way on the S5 as the 6 ports do; that would be they only open when the engine is in gear or under load. You are not going to see these things operate in your driveway. You need to put something on it to see if it opens when you are flooring the car all the way up to redline. You also need an air pump on the car incae you have removed yours.

I have also heard by word of mouth that the VDI is only worth about 7 horsepower and I have seen back to back dynanometer graphs that show the 6PI are worth 18-20 horsepower.

You can feel the VDI kick in around 6K... it's a pretty significant boost.

I think...

Take the actuator apart, lube it with white lithium grease, then check to make sure that:

1. Air pressure into the nipple moves the acuator.

2. The VDI solenoid works (use a battery).

3. That the VDI plug on the harness is in working condition (as per the FSM).

Really, if it's a race motor, just wire it open. You'll be spending most, if not all of your time in the upper RPM bands anyway.

too bad it's technically not legal under ITS........ =P

VDI actuator directly connected to the air pump which is part of the smog system. Might be thin, but I'm not going to lose sleep over it.

PaulC

Heck, with the recent ECU changes, I can just claim that wiring it open is effectively something I can do with the ECU anyway...

Actually, as Sllkworm pointed out that since you may get rid of the air pump anyway, wiring the VDI into a fixed position is a reasonable (and defensible) action under the GCR.

-bill