Hey guys! Recently got around to doing some work on the car (February 05 R53, 6MT; needed new shift cables) and tried to start it again after 3-4 months of no running. I had disconnected the ECU (after disconnecting the battery), so I guess I'm not surprised that there are codes. After reassembly, the car struggles to start: it'll crank, fire a few times, and then die out. I was able to get it to idle by performing an ECU reset, and then holding the pedal down to keep the idle high. After removing my foot from the pedal, the idle dipped to ~600 but recovered to 1,110 (so, expected behavior really). Seems okayish after that, but I'd still like to get my head around the codes, so any light you all can shed would be greatly appreciated.

Probably important to know that, prior to the work being done, the battery had dipped to a measly 3 volts. I know, I know, I'm awful. I haven't had to go many places with the whole pandemic thing.

Codes:
Engine-DME Digital Engine/Gearbox Electronic 2: 1688/not present: DME Electronic throttle monitoring, level 2/3, air mass - calculation error
EWS Vehicle Immobilizer: 0F Voltage Supply. EWS3 control module (I'm guessing this was related to the battery dying in storage)
ABS-DSC Stability Control MK60: 5E1 9/not present: ABS-DSC: CAN data error from DME/DDE (DSC lamp on as long as error is present)
SBBF Seat Occupancy.passenger: SBBF: Undervoltage
KOM Instrument Cluster: 92 KOMBI MRSZ5: malfunction in airbag system || 61 KOMBI: CAN bus, no communication || 67 KOMBI: CAN bus, no message 1 from KOM2 || 11 KOMBI: Tank sensor 2
Airbag-MRS Multiple Restraint System V: 92 KOMBI MRSZ5: malfunction in airbag system
ZKE Central body electronics: So many different open circuit codes, pretty much for each light on the chassis.

I've since cleared the codes and am waiting to see how many come back.

Seemingly related, my passenger seat occupancy sensor seems to be on the fritz, but I'm not sure if it isn't just the ECU being funky. The light on the center console will flash on and off occasionally, even when I push down on the seat.

 

Might also be worth to check some earth straps here & there. And keep measuring the battery to see if its still holding up (else replace it). Also with ethanol being added to fuel, sitting still for 3 months might be a disaster.

 

Maybe being off so long it developed corrosion on the DME harness Pins. Quite delicate.

 

Fuel pump. That’s a wild guess but from ur description sounds like when mine went out...

 

Perhaps remove the ECU again and reinstall. I have run into a few situations where I had to do this.

 

All of the codes except for

Engine-DME Digital Engine/Gearbox Electronic 2: 1688/not present: DME Electronic throttle monitoring, level 2/3, air mass - calculation error
ABS-DSC Stability Control MK60: 5E1 9/not present: ABS-DSC: CAN data error from DME/DDE (DSC lamp on as long as error is present)

haven't come back. I was initially hopeful since I was able to get it to idle for a time, but it's started dying after a few seconds of running again. I've inserted/removed the ECU harness a few times on both sides, figured the action would scrape off light corrosion if that was an issue. Battery is new as well, so that should be alright. I'm leaning towards poor summer-mix gas, as I was driving very infrequently even before storing it. Guess I'll be pumping it out and replacing it this weekend.

Out of curiousity, I looked around for stock images of the JCW airbox, and noticed that it had a few more connections going to it than mine did. Specifically:


I don't recall seeing that vacuum hose in the lower left corner. Are there connections I might have unplugged while removing the airbox that I totally glossed over in replacing? I imagine there's also a connection for that little unit inside the airbox that opens the bypass at the rear?

 

JCW Airbox Installation

 

Hey again. Finally got around to draining the tank and swapping with fresh fuel, and it'll actually hold an idle now - just, a very rough one. Frequent dips to 500-600 RPM, lugging, etcetera. Also seems to be stuck in limp mode, since the throttle doesn't do anything at all. Checked out some live data, and noticed that one throttle pot only reads 1.11v while the other reads 3.90v. Pedal travel sensors (sensors 1 and 2 respectively) read 0.36v and 0.72v at 0%, and 1.96v and 3.95v at 100%.

I'm leaning towards the sensor connections on the throttle body being the issue here - corrosion, gunk, something along those lines. Thoughts?

Error codes are:
1688/not present: DME Electronic throttle monitoring level 2/3, air mass - calculation error
1229/present: DME: Throttle potentiometer - adaptation fault
638/not present: DME: Throttle - malfunction (flap malfunction)

 

You might just try a few things:
- Reset the drive-by-wire throttle synchronization - ignition on, floor the gas pedal for 15 seconds, ignition off & key out, release the gas pedal.
- Clean all the electrical grounds.
- Use electronic switch cleaner on any suspicious plugs & sockets.
- Take the car for a decent run - 10-15 miles at least.
& see if there's any difference.

 

Again, I'm seeing a common theme here, don't you ?

 

Did you do what Eurothrasher suggested about the JCW airbox install? Namely, the hose connection to the ByPass Valve? That's probably why your idle is so rough.

 

Sorry guys, trying to keep up :p not to put too much blame on the previous owner, but it seems they dropped the JCW airbox in without any of the supporting hardware like the cable splices and vacuum hoses, and I'll have to figure out that retrofit. Was hoping to ignore it a little while longer since it seemed to run alright without the things before, but maybe it's time to give it a look over.