EGR Adaptation fail

[LB123]

After two problem free years on the 1.4 16v BBZ engined Fab it has started to run rough and showed a CEL. VCDS reported a misfire on 3 which a new coil on plug cleared. Unfortunately I noticed that the air pipe on the EGR valve had fatigued off or been broken of the body so I fitted a new EGR valve, cleaned EGR pipework and throttle body. TBA went fine with the full VCDS I have but EGR adaptation gave an 'ERROR'. I have repeated the EGR adp a dozen times. Each gives 'ADP Run' in the box on switching from memory blocks to basic settings for about 2 seconds and then changes to ERROR. Coolant temp is 16C and voltage 12.3v. Measuring blocks 74 show 0.53v 4.46v 0.531 and ERROR. Each time I switch on the ignition the same two codes come up, only the second of which can be erased.

The CEL is off and the car is running fine now although I have only driven a couple of miles. I can only think GSF have supplied a duff EGR or I have a loom fault. Any way of checking this please?

Nigel

Log-WL04UUW.txt

[Breezy_Pete]

Put the old EGR back on and see if that works? That would rule out wiring issues. Do you mean the little spigot that the small rubber hose attaches to, when you say 'air pipe'?

 

[LB123]

Yes the spigot the rubber pipe attaches to. Reading other threads this probably doesn't matter.

Have just been for a drive to see if hot coolant might change the result. It did but not in a useful way. Just changed the reading in 74.4 from 'ERROR' to 'TEST Off'. Possibly coolant too hot?

Will try the old EGR valve.

Edited 27 August, 2017 by LB123

[LB123]

Just changed the plug over to the old unit with it lying on the rocker cover so body earthed. Different set of voltages in the windows of 74 but a return of the 'ADP Run' with a longer delay of about 4 seconds before it reverted to 'ERROR'.

Coolant temp 80C and battery 12.4v.

Edited 27 August, 2017 by LB123

[Breezy_Pete]

I don't think the body is connected to any of the electrics, so earthing it shouldn't matter.  Are the voltages still close to zero and close to 5V?  Wondering if you should be checking a fuse for the solenoid, let me see which one.

[Breezy_Pete]

Fuse 7 in the cabin fuseholder, 5 Amp

[LB123]

Fuse 7 is visibly and electrically good.

 

Edited 27 August, 2017 by LB123

[Breezy_Pete]

Do all the wires look OK at the point the loom goes into the connector? Do the socket bits inside the loom connector look clean?

[LB123]

All clean. Checked the wires continuity from the EGR plug contacts back along the loom for 6 inches yesterday so if its a loom fault it's not at the plug. I have not run a full continuity check back to the ECU because I don't know where the five wires are supposed to go. I imagine to the smaller of the two ECU plugs but which pins. Should I be expecting any live volts at the EGR plug?

 

There appear to be two different EGR valves for AUB/BBZ engines. Earlier solid body type and later one with a sort of bellows type upper body. I bought the later type as the chassis number is ****** 6Y7 44131231.

I don't suppose I have the wrong one possibly?

[Breezy_Pete]

I can check all those things for you shortly, have to mow the lawn first though.

[LB123]

Thanks. I'm just loafing in the sun down here in Plymouth.

[rum4mo]

I replaced an EGR valve with a genuine VWG one which had the "bellows" top section, but I think that it is just heavy ribbing to improve cooling or prevent over heating of the solenoid coil. Is the GSF one a Pierburg  - if so check up if it is the correct one on the Pierburg website - though I think that you have proved that you have the same issue with the old one?

[Breezy_Pete]

036 131 503 T should be right for your car, which translates to Pierburg 7.28248.17.0 I think. Like this one: http://www.ebay.co.uk/itm/PIERBURG-7-28248-17-0-OEM-EGR-VALVE-/162616981969?epid=1705798990&hash=item25dcba39d1:g:iiMAAOSwMVdYEMRC

[LB123]

Yup, that's the one. Not a pierburg one. I bought from GSF a Vetech one.

Just noticed a post in an old thread. Check volts between terminals 1 and 5 in the plug. I got 9V.

Edited 27 August, 2017 by LB123

[sepulchrave]

It is possible that the new valve is faulty as well as the old one, however the ECU is very finicky about voltages returning from the PWM oscillator compared to actual EGR values measured by the MAP sensor, it is also possible that the MAP sensor is dirty enough to give slightly inaccurate readings throwing the ECU off.

 

If the valve is working then I would just ignore the CEL and drive it, the CEL will go off after a while anyway (50 starts or somesuch).

[Breezy_Pete]

Try pin 1 to battery negative/chassis, should be 12ish V, same as what you might measure at fuse 7 with ignition on.

 

Wiring as follows:

EGR pin     Wire colour(s)   Destination/source

 

1                 Black/red            Ignition 12V via Fuse 7

2                 Red/green          +5V (from engine ECU, I should think, working on that, yep pin 98)

4                 Brown/blue        0V/earth, also to ECU pin 108

5                 Purple/white      ECU pin 114

6                 Green/white       ECU pin 100

Edited 27 August, 2017 by Wino

[LB123]

Thank you for the wires and all the help. I can now troubleshoot the loom which I will do this evening. And get back with results.

[Breezy_Pete]

By way of explanation of the above wiring; the solenoid is powered by 12V on pin 1, and modulated by the engine ECU earthing pin 5 PWM-fashion to variably move the valve against the return spring.  Pins 2, 4, 6 are to the position feedback potentiometer, pin 6 being the wiper contact.

[LB123]

Rats. A confusing picture.

1. 12.3v

2. Continuity to 98. Only 1.93v when plugged in and ign on.

4. Continuity to 108.

5. Continuity to 114.

6. Continuity to 100.

However there is a hint of a high resistance short between 2 and 4. I presume they should have no interaction but, with both plugs disconnected, putting test probes into 2 and 4 there is a brief fluctuation on the meter which then registers no continuity as it should. This doesn't happen with any other pair.

And pin 2 can only muster 1.93 v rather than 5.

 

Looks like the wire pin 98 to 2 might be suspect. Cheap dirty fix would be to isolate it, cut it close to both plugs, retest and the substitute a new run of wire from the stubs on the pins.

 

Or unwrap the whole loom and chase both wires looking for damage.

Edited 27 August, 2017 by LB123

[Breezy_Pete]

There are other things connected to the +5V and sensor earth that may account for the behaviour with your meter, I think. Let me see what those things are, then you could disconnect them too to prove. It could also be that one of those other things is what's pulling the 5V down.

[LB123]

Not such a quick dirty fix then!

[Breezy_Pete]

Cam sensor and MAP sensor are the other things on that 5V rail as far as I can see. Try unplugging both of those and repeat your tests. (You'll probably add various new fault codes if/when you switch ignition on with all these things disconnected, but they'll go away easily).

[LB123]

Steady on 1.94v even with MAP and Cam sensors disconnected. I'm going to try the dirty fix. It removes the possible short and I can always go back if it doesn't work.

 

[Breezy_Pete]

Fair enough.  Only other thing I can think about the 1.94V is that it's just possible that the ECU only puts that 5V out when the engine is cranking or running, as opposed to ignition on. Would surprise me quite a bit though.

 

Thinking about it, that couldn't work I don't think, because EGR adaptation doesn't require cranking/running and it must use the potentiometer.

Edited 27 August, 2017 by Wino

[LB123]

Pin 98 is also connected to the manifold pressure sensor so that has been disconnected by my cut and produces a fault code. The EGR adaptation does not run at all rather than as before running for a second or two and then flaging up 'ERROR'. Perhaps because one of the conditions is no fault codes or one of the other parameters is not met. Think I will call it a day and repair the change I have made tomorrow. Might just have to live with it un-adapted. Many thanks for your guidance and knowledge Wino.