Hard Cold Start and VANOS Error Codes

[sapote]

FIXED.

Man I love this forum. Based on you and saopte's statement that those pins should be chassis ground I checked the e-box and the large ground connector (X6053) was loose! No wonder it was running like dogshit! Wow I feel like an idiot! Thanks everyone!

Also fixed my oil level sensor issue!

So that loose ground connector X6053 must had about 12.8V floating voltage instead of 0V when reference to chassis ground. This is why with pin1, 3, 4, 6 at zero voltage (I bet the DME didn't active the solenoid when you measured the voltage) and you measured with negative -12.8v. If the DME activated the solenoid and supplied 12.6v to pin 1, 3, 4, or 6, then connector X6053 must be at 25.4v to cause the measurement to have -12.87v, and 25.4v is too high to exist in this engine.

[heinzboehmer]

FIXED.

Man I love this forum. Based on you and saopte's statement that those pins should be chassis ground I checked the e-box and the large ground connector (X6053) was loose! No wonder it was running like dogshit! Wow I feel like an idiot! Thanks everyone!

Also fixed my oil level sensor issue!

Nice! Gotta love free fixes. I'm glad you checked the ground on that connector, otherwise you could have spent a ton more time chasing this issue.

[eacmen]

I just probed my VANOS solenoid ground and it's the same as chassis ground. TIS says it is too (see below). If yours isn't, then I suspect this is your problem. Have you checked the wire bundle leading to the solenoid? They sometimes get messed up in the thermostat housing area. You can also check the ground bundle in the DME area, under the yellowish plastic bracket that holds the DME.

FIXED.

Man I love this forum. Based on you and saopte's statement that those pins should be chassis ground I checked the e-box and the large ground connector (X6053) was loose! No wonder it was running like dogshit! Wow I feel like an idiot! Thanks everyone!

Also fixed my oil level sensor issue!

[heinzboehmer]

I just probed my VANOS solenoid ground and it's the same as chassis ground. TIS says it is too (see below). If yours isn't, then I suspect this is your problem. Have you checked the wire bundle leading to the solenoid? They sometimes get messed up in the thermostat housing area. You can also check the ground bundle in the DME area, under the yellowish plastic bracket that holds the DME.

[eacmen]

I don’t think think there is negative voltage needed in this engine; how did you measure that negative -12.8v? Where the black lead touched?
Pins 2 and 5 should be zero Ohm to ground.

Tested with black lead on pins 2 and 5. Then red lead on 1 3 4 and 6.

I know other BMW engines with solenoids reverse polarity on the solenoid to open/close. So I wasn't surprised when I measured negative voltage on the S54.

[sapote]

One thing to note is that the ground on the connector is *not* chassis ground. At steady state with the valves deactivated the ECU seems to hold the solenoid at -12.8v. When the ECU commands the valve open it seems to supply a little under 300mV.

Anyone aware if this is normal operation for the VANOS solenoids?

I don’t think think there is negative voltage needed in this engine; how did you measure that negative -12.8v? Where the black lead touched?
Pins 2 and 5 should be zero Ohm to ground.

[eacmen]

It's not the same as chassis ground? That doesn't sound right. I'll probe mine in a bit to confirm, but the wiring diagrams on TIS suggest that it should be.

One other thing you could do is load up Testo and look at the target value for each cam vs the actual value. Should give you some idea of whether the issue is mechanical or electrical.

Yeah that was weird. I probed ground pins and touched the water pump with continuity and nada. If you test continuity between the two ground pins then there is continuity. And clearly there is a circuit between those two pins and the solenoid or there would be no voltage measurement. I am thinking the ground might be isolated from chassis ground because the voltage regularly swings from negative to positive?

Engine is running very rough, I am opening up the valve cover now just for peace of mind. Havent done a valve adjustment in a while so couldn't hurt. Just didnt feel like doing it before the winter.

Its weird though at first start its pretty smooth for like 5 seconds. But then it starts running very rough.

[heinzboehmer]

It's not the same as chassis ground? That doesn't sound right. I'll probe mine in a bit to confirm, but the wiring diagrams on TIS suggest that it should be.

One other thing you could do is load up Testo and look at the target value for each cam vs the actual value. Should give you some idea of whether the issue is mechanical or electrical.

[eacmen]

I decided to test if the ECU wiring to the VANOS connector is good. Using the Foxwell/Schwaben tool was able to command each VANOS solenoid valve individually. Used some standard pin headers, minigrabbers, and a multimeter to test voltage going to each of the solenoids. One thing to note is that the ground on the connector is *not* chassis ground. At steady state with the valves deactivated the ECU seems to hold the solenoid at -12.8v. When the ECU commands the valve open it seems to supply a little under 300mV.

Anyone aware if this is normal operation for the VANOS solenoids?

While doing this experiment was able to map which pins on the connector are which solenoid:

Pin 1 - Intake Retard
Pin 3 - Intake Advance
Pin 4 - Exhaust Retard
Pin 6 - Exhaust Advance

[eacmen]

Replaced solenoid and still getting codes and rough running. VANOS oil pressure still good.

Any other diagnostics to try before tearing into valve cover?


Sent from my iPhone using Tapatalk

[eacmen]

Don't suppose you let it fully warm up and monitored the pressure? As it warms up and thins the pressure likely drop a little.

No, just wanted to rule out oil pressure issues before dropping money on solenoids. With the VANOS codes the engine is running like total crap and I didn’t want to run the engine like that very long. I’ll test it again with fresh solenoid.

[maupineda]

Yes, measurement should be at an oil temp of more than 70C. But pressure should be maintained

[Shonky]

Don't suppose you let it fully warm up and monitored the pressure? As it warms up and thins the pressure likely drop a little.

[eacmen]

I did a pressure test just for sanity's sake to rule out any oil pressure or pump issues. Looks healthy. pressure at idle around 1650psi /113bar. And pressure drops slowly when engine shut down so accumulator seems healthy.

Video here if anyone is interested:

https://www.youtube.com/watch?v=QNnKgNjBJe4

[eacmen]

So far all I have heard the weak link is the solder joints. The head temperature is close to 90C to 100C and went through many heat cycles, leading to solder crack. Using lead-free solder can lead to solder joint crack easier than the old lead solder, as the former is more rigid and fragile than the old softer solder.
I would think adding 8 wires from the solenoid solder joints to the connector pins solder joints will take care the cracked joint, as the wires bypass the pcb traces with the cracked solder.

Agreed! Was thinking the same exact thing. Would just need to tap some holes in the valve body to mount individual solenoids and wire em up to the connector with maybe some voltage regulation between the connector and solenoid. Anyway maybe a side project I might spend some cycles on at some point.