Does the VDI need a load to open?
 

I reved my friends 91rex to 7 and still the vdi would not open. Anyone?

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I just checked the FSM. Doesn't say in there... :(

Just take it out for a spin. I can actually feel the VDI kick in at around 5.5k. :zip:

If you look at the control matrix on page F1-77 of the FSM, it says the VDI only operates under “heavy load”.

Never set eyes on a VDI, but maybe you could simulate load by taking the vac hose off the boost/pressure sensor and then reving the engine. Or if that did not work apply a couple of lbs of air pressure with a Mittyvac to the boost/pressure sensor while reving the engine. Just a thought. Or you might be interested if the solenoid is getting a signal to open while you drive the car. Maybe patch a set of long leads to the solenoid and monitor the voltmeter in the car while driving. Or pick off the solenoid signal at the ECU and run your meter leads to it and watch what happens while driving. Or get simple and buy a long vav hose and run it from the outlet of the vdi solenoid to the drivers seat and drive the car while monitoring if the hose gets pressure when putting a load on the engine. Or jumper the inlet and outlet hose of the vdi solenoid and eliminate the solenoid to see if the vdi moves. Or pull the plug off the VDI solenoid and jumper a ground and 12v to it to see if the vdi works. Darn, I just gotta get me a car with a vdi so I have something to do. You guys have all the fun.

uuuu. thnx.

WHO ARE U?

According to the input/output matrix on page F1-76, the VDI system uses the crank angle sensor (rpm) and the airflow meter (load) as its inputs, not the manifold pressure sensor. Go figure...This would be the best way to see if it's working, but I'd tee into the line so the VDI still works, and I'd put a pressure gauge on the end so you can see if the pressure's what the FSM says it should be.

In my 89 convertable I can feel the VDI kick in.
In my "new" 91 convertable I feel nothing.
Just started checking. the 91 hose is hard. Am swiching the hoses to the actuator to see if there is a leak.
Any other ideas?

its easy to do, pull one of the vacuum line to the VDI. Then just blow air in it. You should see it move

tmak26b has a good idea to see if the vdi itself works, but you also need to know if the solenoid is working to actuate the vdi, so you need to determine if the solenoid is getting an input from the ecu and if in fact the pressure is getting from one side of the solenoid to the other. Just driving and *feeling* shouldn't be good enough for you. You need to *see* the output of the vdi solenoid in real terms(real terms, what the hell does that mean?). Get radical, man. TAke the hood off. joke.

invest in a cheap vacuum gauge, hook it up to the hose that goes to teh VDI. It should read 2.7 if I remember right

THnx guys...Another? If I plug that hose that goes to the VDI , Will the ecu get confused and have a bad idle.??

The ECU shouldn't cause the car to have a bad idle if you plug the hose to the VDI. The ECU is not that clever. Like NZCONVERTIBLE said, it only works under heavy load. I think you should see if the VDI is working under heavy load. If it is not, it should not be difficult to fix. Its just a simple solenoid that has air supplied at one end of the solenoid, and when the ground signal from the ECU is put on the solenoid, the valve opens and ports air to the VDI. It seems just a matter of seeing if there is air pressure at the solenoid and if there is then checking to see if one wire on the solenoid has 12 volts and if that is the case, then seeing if a ground signal is being put on the solenoids other wire when the the ECU detects a heavy load.

Gotcha..thnx again.

Yo,


I've got Series 5, and I can make the VDI open just by revving it up high at idle. When I say high, I'm talking 6-7K. You can actually see the little actuator move under the manifold.

What I've been told is you can NOT make the 6 port actuators move at idle. Those have to be under load to work. But the VDI is a different story.

My two bits.

KS
1989 GTUs "Look ma, no turbo!"