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Discussion Starter #1
Greetings! Powerstroke monkey here in over his head on a side project.
2003 Passat 4motion 2.8 v6 auto.

Parts used so far:

New OEM coolant temp sensor.
Two new Bosch upstream o2 sensors OEM
Replaced intake manifold gaskets with OEM gasket
Replaced pcv valve (puck style)
Replaced pcv hard tubing Replaced old fabric vacuum lines

Main concern is vehicle does not enter closed loop mode after reaching operational temperature. Vehicle was driven 100 miles over the weekend to try and get readiness set. Vehicle never has achieved a closed operation and yet does not set DTC for any of the components misbehaving preventing closed loop.

Interesting observations:
When key is out, shifter can be freely moved through gears.
Vehicle came with an ECU that looks like it was bought used (had a sticker saying Immobilizer was disabled and had the magic ecu PIN# on it).
Vehicle exhibits a very slightly choppy idle (assuming running on default map is the cause).
Vehicle feels very fast for a heavy awd sedan.
MAF reported flow rates make sense.
IAT reported temp makes sense.
Upstream o2 sensor voltages make sense for narrowband sensors.
No MIL or DTC after 100 miles varied city/highway.
Vehicle has fresh 92 octane gas.

I am beginning to run out of logical diagnostic steps besides swapping ECU for one that I know is bone stock unmodified. The only clues I have so far is the idle is very slightly rough, the vehicle runs great when driven, and VCDS Measuring Block 099 always says O2 Regulation is off (open loop).

Thank you in advance!

IMG_2186.jpg IMG_2187.jpg 55735503924__A3E62D31-F95D-4919-AE56-282A794ECF99.jpg
 

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Since it looks like (and acts like) the car is chipped, I expect the 2nd O2 sensors have been coded out as well. The primary sensors should be wide band from what I have heard. I know very little about closed vs open loop, but it seems that if the primary O2 sensor voltages are adjusting the mixture, it should be in closed loop. How is the MPG?
 

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I do not believe they were OEM equipped with Wideband sensors. If someone else can chime in to confirm or deny, that would be great. Bosch #16287 was used.

Presently, the ECU is ignoring the upstream O2 sensors, thus the system is never entering closed loop operation.
 

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That ECU is a 'black box' at this point since you have no idea what is inside of it. You can do a bunch of tests measuring the outputs vs known inputs to try to see how it behaves or ..... just swap in a known stock ECU and start over. It seems near certain that the current ECU has been re-programmed so there is little chance of knowing what it is doing unless you can find someone to read the current coding and then reverse engineer it.

If you use VCDS to do the ECU swap you will need the ECU PIN number from the replacement (stock) ECU. I've been able to get the PIN from a junkyard ECU using the Xtool VAG401 but it's much, much easier to retrieve the PIN when you can actually start the car so I'd try to get one from someone parting out a V6 instead of trying a junkyard unit.
 

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Thank you for the reply. I agree with you not being able to eliminate variables until I have a known stock ECU. I have the SKC from the current "Unknown" ECU, and I intend to remove the Unknown one and set it aside, install a known good one and attempt to use a tool called Vag Tacho to recover the SKC from the "new" one.
 

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If you have Vag Tacho then you should be set ;) I've never used it but it sounds like it can do just about anything when it comes to coding ECU's, clusters, etc.
Can you read the ECU firmware with that? Maybe someone could tell you what the ECU is doing if you can read the firmware off it.
 
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