Glow plugs going to trash!!! Please help :(

[gaspard]

Hi OysterGray,

I replied to you PM, thanks.

I'll just say here that unlike you down there in Portugal, here in France we have a proper winter and can expect a couple of weeks at least of -10°C after christmas... this will be a problem for my glow plug-less audi!!

So I will be trying everything to resolve it... only I don't really know what that 'everything' is, so any help or suggestions are most welcome and slightly urgent!

Cheers,
Tom.

[OysterGray]

Hi OysterGray,

I replied to you PM, thanks.

I'll just say here that unlike you down there in Portugal, here in France we have a proper winter and can expect a couple of weeks at least of -10°C after christmas... this will be a problem for my glow plug-less audi!!

So I will be trying everything to resolve it... only I don't really know what that 'everything' is, so any help or suggestions are most welcome and slightly urgent!

Cheers,
Tom.

Yeah, you really need that glows working right....
I have a last resort suggestion.... You can build a custom wiring for the glows to work, you can switch them on/off manually or even construct some timer... I'm no electronics expert but I think the problem would be the resistor you might need to drop the voltage to 3 or 4 volts, because of the high amp the glows work on.... It would take a HUGE resistor :O
Or... You can always try to find a set of glows that work on 12v and are the same length and thus will fit the engine.... I don't know if this is really possible however...

[gaspard]

OK, back with a little bit more info.

So recap, my glow plugs are burning up in a matter of seconds. I have replaced the control relay, it made no difference.
Today I checked some voltages on circuits. The plugs are getting the correct voltage at start up, but when they are supposed to switch off they go back up from 4v to full battery voltage (~14v) that is the the end of that!

This happens about one start in two, and when it does they stay at this voltage until about 20 seconds after the car stops. There is a whining noise coming from somewhere in the engine V after engine shut off, this goes on for the same time, then stops as the egr solenoid releases with a clunk and the voltage at the glow plugs drops to 0.

When it doesn't, everything would work fine... except that the plugs are already burned out, so it doesn't make any difference to starting.

I checked some voltages in the gp relay connector with relay absent... main supply full batt voltage, 6 connectors to GPs 0v, a brown earth, a red+green 12v, and two others that read 12v and 9v.
When checked with relay in place and engine running... main supply full batt voltage, 6 connectors to GPs full batt voltage, brown still earthed, red+green still 12v, the two others drop to about 9v and 5v.

When I turn off the engine the main supply stays live, everything else is 0v except the red+green which stays at batt voltage until about 20secs after shut-off when everything switches off, the whining, the egr valve, the GP voltage.

So maybe the signal in the red+green wire is what is causing the GP relay to supply batt voltage, but where does that get me?

Is the whining sound followed by the clunk of the egr valve normal for this engine after shut-off? Can anyone confirm?

Does it have anything to do with the clicking/clacking (sounds of actuators) I also hear from the engine bay from time to time just walking past the car hours after having switched it off?!?

All connections inside the box containing the ecu look perfect. There is no sign of water ingress, everything is super shiny and like new.

I get the feeling it runs lumpy when producing this 14v on the GP lines... as if this GP problem is just the most visible sign of some other electronic problem...

Any ideas?

This is a massive problem for me, and seems unfairly rare!!

just to give all info, I have changed the battery for a 110ah varta which I coded to the car using codes found on a german site, and which didn't make any difference! I also get a clicking clacking from the central heating vents sometimes as though the actuators are going back and forth from 0 to 100 again and again for a few seconds. The only fault codes are the GPs and the GP relay.

As always, please help...

[OysterGray]

Same as me, replaced relay but also made no difference.
But my glows doesn't get the correct voltage at startup, they simply get no voltage :/. Only when I get the engine to run, they start to get full voltage... how weird
I can confirm that the whining sound is normal, my car always did that. Also, the GP voltage also cut after that clunk from the egr.
Also, my car doesn't always start at the first attempt, as if the starter tries to engage but do nothing.... don't know if related.

Man, this is really a WEIRD problem
Hope you find the problem... I really want my glows back

[gaspard]

There has been some progress on Oystergray's post over on ross-tech forum... here.

Suggesting that there have been earth problems that have caused ecu damage. so engine earth loom to be checked/replaced followed by ecu... that sounds simple and cheap��

[gaspard]

OK, I am back a year later to inform you that I have resolved the issue. New battery, new engine earth strap, new glow plug relay, new glow plugs. That was the starting point. Then I had the wiring tested at audi - no, not free, but €240 to assure me that there was no further wiring fault and get the latest engine ecu software upgrade. So only one component left to replace! I purchased a matching second hand ecu from Lithuania for €200 and had a guy in Lyon clone my original ecu data onto it for €140. I received the Ecu on Saturday and even with this cold damp weather the car now starts and runs smooth and smokeless in less than a second in the morning as opposed to about 15 seconds of cranking plus billowing smoke before!

So, I am the second person that has resolved this issue by changing the Ecu. The other got a new Audi ecu which might mean he is now homeless. Anyhow, I hope this gives hope to Oystergray... It works, and doesn't have to cost that much. Be warned, if going ahead with the replacement, be sure to replace the engine earth strap first to avoid burning the second ecu.

Enjoy.

[OysterGray]

Many thanks gaspard for that precious info... I have not fixed the car yet. I think this may also be useful for many other Audi A6 owners....
Merry Christmas and a happy new year.