My vanos is stuck on

[JGood]

So my vanos is stuck on. I have 12v coming from the harness at all RPM's, as opposed to just ~1k to ~5.5k. What would cause my ECU to not deactivate vanos? I'm losing top end power, when I unplug the vanos and drive it, I have no low end but it screams up around 6k.

It's a 94 e34 m50 with s50 cams and a TRM tune.

[M-technik-3]

So your saying the solenoid is defunct or you are always getting power to it? Just wanting to make sure I understand you correctly.

[JGood]

I am always getting power to it. The solenoid and all other vanos components work as supposed to.

The DME should provide 0 volts until ~1k PM's, then provide 12 volts. This activates vanos. Then The DME cuts the 12v supply around 5.5K RPM's, which deactivates vanos.

Here is the wiring diagram. Actually, it looks like the DME actually cuts the ground supply to the sensor, as opposed to cutting the positive supply. Positive comes from the main relay.

[JGood]

Another...

[JGood]

I guess my questions are:

Does the DME use any info to determine vanos engagement other then RPM? Could another sensor (knock, for instance) that has an out of spec reading, cause the DME to advance timing at all RPM's?

Could the DME be bad in a way that would cause normal operation, except for this?

[Dissembler]

The computer needs a road speed signal before it does anything with vanos AFAIK, which is why you need the wire from the back of the cluster that goes to the pin 20 of the x20 connector

[JGood]

The computer needs a road speed signal before it does anything with vanos AFAIK, which is why you need the wire from the back of the cluster that goes to the pin 20 of the x20 connector

That's the thing, the computer IS doing something with vanos, it's engaging it permanently. As soon as the car starts, it sends the signal to vanos to engage.

And I do have the road speed signal hooked up. Proof of that is my ability to rev to 7000, I think? Because with no speed signal aren't you in limp mode, with a rev limit of ~6300?

I'm going to try my old chip today, just to be sure it's not that.

[hoveringuy]

VANOS will be engaged when the motor has warmed a little bit and under load until around 5200 rpms. If I rev my motor hard while parked my "V" light will light (VANOS), so I don't think road speed is involved.

ECU will complete a ground to the solenoid. Solenoid should always have +12 volts with ignition.

How do you know what the VANOS is doing?

[JGood]

ECU will complete a ground to the solenoid. Solenoid should always have +12 volts with ignition.

How do you know what the VANOS is doing?

That matches my finding as well (post #3, not the 1st post). I know what vanos is doing because I can feel it. I haven't checked with a multimeter that the DME is or isn't cutting ground, but I'm 99.9% sure it is.

Unplugged: No midrange, pulls hard above 5k, espeically around 6k.
Plugged in: Lots of low end torque, doesn't pull as hard above 5k

It's not placebo effect, it's a very noticable difference. At least 25hp or so.

If the car is running, and I plug vanos in, it stumbles. This is at idle, when vanos should not be operating. That proves it's engaging at idle.

[JGood]

If the DME is sending signal to activate vanos, that might mean it thinks vanos is engaged, which means it's not giving me the proper maps in the top end, even when I have vanos unplugged? So although I'm getting more power up top, it' might not be nearly what it should be? Or maybe it uses the cam position sensor to decide where the cam is, and what map to use for map selection, in which case I'm already getting max power up top with vanos unplugged...

I hope there's even more top end power to be had when this is all straightened out :)

Are there any diagrams or articles out there that describe this kind of stuff, how these DME's work?

[JGood]

While I'm blabbering...

How hot are these DME's supposed to get? I know mine gets so hot that I can barely hold it. The case is not grounded to the car, just laying in my glovebox. Do either of these things sound bad? I didn't think they should get that hot, and I hope it doesn't need to be grounded to operate properly. It'd been running fine other then this vanos issue, for the last 2 years.

[hoveringuy]

You can't neccesarily just check continuity to ground on the plug because it's going through a MOSFET. There will be resistance.

Get a 12v LED at Radio Shack. Connect the +12v side to the battery, connect the (-) side to the ground side of your solenoid. Tape the LED to your wiper arm.

If it is truly stuck on disconnect the ECU from the harness and check for shorts to ground. It's also possible that the electrics are working fine but the solenoid is physically stuck. Unscrew it and check that the plunger is free.

[lifeiskaos]

While I'm blabbering...

How hot are these DME's supposed to get? I know mine gets so hot that I can barely hold it. The case is not grounded to the car, just laying in my glovebox. Do either of these things sound bad? I didn't think they should get that hot, and I hope it doesn't need to be grounded to operate properly. It'd been running fine other then this vanos issue, for the last 2 years.

They don't need to be grounded, but it helps a bit in heat dissipation to be bolted in

[JGood]

You can't neccesarily just check continuity to ground on the plug because it's going through a MOSFET. There will be resistance. Get a 12v LED at Radio Shack. Connect the +12v side to the battery, connect the (-) side to the ground side of your solenoid. Tape the LED to your wiper arm.

I was going to plug both leads of the multimeter into the vanos harness plug, one ground and one positive, then measure voltage. Should be +12v when engaged, 0v when disengaged, no?

I'm not expecting to see chassis ground continuity in the vanos plug. That may be the case, but as you said, might not prove anything at all.

If it is truly stuck on disconnect the ECU from the harness and check for shorts to ground.

You mean connect my multimeter to the harness wire that engages vanos (pin 7 at the DME plug), and check for continuity to anything else (chassis ground and other harness wires)? That makes sense to me, and was one thing I wanted to try.

It's also possible that the electrics are working fine but the solenoid is physically stuck. Unscrew it and check that the plunger is free.

If that were the case, I would not get a significant power increase up top by simply unplugging the solenoid. It would also not create a change at idle when simply plugging the vanos solenoid in (it stumbled and almost stalled, but a restart of the engine allowed it to idle smooth again).

[hoveringuy]

If I unplug my solenoid at idle it will stumble and idle like crap, too. That's not because it's engaging the VANOS when it's not supposed to, but because the ECU checks the solenoid when it starts. It needs to see that load.

Only way around that is to put a 100Ohm power resistor in there to satisfy the ECU.


Edit: Re-read and you never said it stumbles at idle. Never mind! Checking for +12v at the harness with the multimeter like you mentioned will work.