For all of you S5 guys, can you feel it when the VDI kicks in at 5,200? My friend just took me for a ride in his 89 GTU, and I noticed nothing after 5,000 RPM's. I mean the RPM's did not climb a bit faster after 5,200. When I put vacuum to the VDI port, I can hear a click, which means it's turning. But what I don't know is if it's working when he drives it. I know the computer controls the VDI solenoid. I don't want to tell him to start troubleshooting if there's nothing wrong.

Mike

 

It's not a night & day switch. At 5k+ RPMs the transition is very smooth, so it just results in a bit more overall pull to redline.

 

I'd check out the solenoid per the FSM. That will most likely check out. Then if you've doubt about the ECU sending the gnd signal to it, go buy a LED from Radio Shack. Wire the positive terminal of the LED to a source of power and the negative lead of the LED to the output wire of the ECU to the VDI.

If the light lights up each time you reach 5200 rpm, then the solenoid is working and the ECU output is working.

You could run the LED wires to the cockpit from the VDI solenoid or directly from the ECU itself. Matters not which. You'd have to by some wire to lengthed the wires of the LED. What? A buck for a roll of 22gauge wire at Radio Shack?

 

Just a quick check - you do have a working airpump and an ACV, right?

-b

 

Actually, he doesn't have the air pump or the ACV. I'll look to see if there is some other set-up that is being used to supply air.

Mike

 

well if theres no air pump, then there's no vdi and no 6 port actuation. those are run on pressure, not vac, and on 89-92 fc's, they are run off the air pump. the acv is not part of it, but if you remove the acv, you'll need to reroute the air pump pressure to the vac line that feeds those entities