TDi - different starting problem

AndyP

Member
I have a very intermittent starting problem on my TDi75, oddly this seems only from cold, but that could be coincidence as it happens so infrequently. Totally randomly and days/weeks/months apart it fails to start, engine turns over well, fires immediately and stops after a second - probably one firing stroke per cylinder. Excactly the same symptoms as if the imobiliser is preventing the engine from starting - I can prove this with my spare uncoded key. The difference then is that the EML light is on and the glow plug light flashes. With my coded key all lights are normal, but it doesn't continue running. It will turn over for 10 seconds, no difference. Remove key, lock/unlock car, try again, walk away, come back, same etc., then randomly, could be 1 minute later or 1 hour later absolutely fine, starts immediately. Initially, I thought this was a fueling problem but now I think it's immobiliser related.
I checked for ECU codes with Torque and found none. I dug out the laptop with VAGcom and there is Camshaft Position Sensor (19464) - (shame it doesn't display how many or the time of the fault). However, this symptom is different and I think occasional Camshaft sensor faults are "normal", plus I replaced it last year anyway.

There is also a 17978 which my shareware version doesn't decode but I just had to Google and I get:

17978 - Engine Start Blocked by Immobilizer
In case of Engine Starting Issues please make sure that you are really experience an Immobilizer related Problem! ... May be stored in Combination with 01176 - Key: Signal too Low in Immobilizer Control Module.


Eureka ! So this probably coincides with me testing the theory with the uncoded key. Now I have to wait for it to do it again to see if I get a fault from the normal key. I'm considering having the imobiliser disabled, presumably that needs the fully featured VAGcom? @timmus @2work - any thoughts?
 

2work

Admin Team
@2work - any thoughts?
Morning Andy,

Sorry to hear your woes. Personally I don’t yet have any experience on this subject and wouldn’t like to hazard a guess as it’s all unknown to me. Anything I suggest wouldn’t be based on no experience and only from understanding what I’ve found out from searching the internet.

Whilst waiting for other Tom to get back to you, you could also contact Paul @depronman as he knows a thing or 2 about immobilisers.

Kind regards,

Tom
 

AndyP

Member
Morning Andy,

Sorry to hear your woes. Personally I don’t yet have any experience on this subject and wouldn’t like to hazard a guess as it’s all unknown to me. Anything I suggest wouldn’t be based on no experience and only from understanding what I’ve found out from searching the internet.

Whilst waiting for other Tom to get back to you, you could also contact Paul @depronman as he knows a thing or 2 about immobilisers.

Kind regards,

Tom
I thought you may have seen similar issues with key coding. I have been wondering whether the thing near the ignition lock that reads the keys is failing.
 

2work

Admin Team
I thought you may have seen similar issues with key coding. I have been wondering whether the thing near the ignition lock that reads the keys is failing.
Hi Andy,

I’ve personally not experienced any issues like you explain whilst coding keys. I have always worked on fully functioning ECUs and immobilisers, all I’ve done is obtain the SKC and add additional keys (new ID48 transponder chip) to the vehicle.

Sorry I couldn’t of been any more help this time round.

I’m sure the either Tom or Paul will be able to talk you through how to work out exactly where your fault may be here.

I’d strongly recommend a repair opposed to deactivating the immobiliser as it could have insurance implications should your A2 find itself in someone else’s hands. Also get the spare key fully matched to the car, a spare is always handy to have.

Kind regards,

Tom
 

AndyP

Member
Hi Andy,

I’ve personally not experienced any issues like you explain whilst coding keys. I have always worked on fully functioning ECUs and immobilisers, all I’ve done is obtain the SKC and add additional keys (new ID48 transponder chip) to the vehicle.

Sorry I couldn’t of been any more help this time round.

I’m sure the either Tom or Paul will be able to talk you through how to work out exactly where your fault may be here.

I’d strongly recommend a repair opposed to deactivating the immobiliser as it could have insurance implications should your A2 find itself in someone else’s hands. Also get the spare key fully matched to the car, a spare is always handy to have.

Kind regards,

Tom
I'd always intended to get the spare key coded, I even have a spare ID48 chip, but well I guess it's been about 11 years, so one day ... ;)
 

2work

Admin Team
I'd always intended to get the spare key coded, I even have a spare ID48 chip, but well I guess it's been about 11 years, so one day ... ;)
Haha,

I’m due to visit your area in a few months (before Christmas). I’m more than happy to drop in and grab your SKC so you can code it yourself with your VCDS or even do it for you. It’s a quick process, no more than 10 minutes.

Kind regards,

Tom
 

Un4tural

Member
Mine did exact same thing with the crank position sensor fault (one behind oil filter/cooler, maybe cam sensor, pretty sure that one is cam?) turn over engine light and glow plug light, then start after a bit of time once it cools down for me anyway, replaced sensor with a new one back to all good, though I had a scanner on hand at the time so was easy to catch, gave me a good scare at the shops parking lot.

Once it started it ran just fine but still had the dash lights on so was a bit of a stressful drive back.

The sensor can fail in a very slow and frustrating manner popping up only now and again, as other posts have documented, I did not risk driving driving mine when I had it and ordered a new sensor. Though from what I recall more prominent when engine is warm.


Could be immobiliser also, but Immobiliser does not flash glow plug light from what I recall.
 

AndyP

Member
Mine did exact same thing with the crank position sensor fault (one behind oil filter/cooler, maybe cam sensor, pretty sure that one is cam?) turn over engine light and glow plug light, then start after a bit of time once it cools down for me anyway, replaced sensor with a new one back to all good, though I had a scanner on hand at the time so was easy to catch, gave me a good scare at the shops parking lot.

Once it started it ran just fine but still had the dash lights on so was a bit of a stressful drive back.

The sensor can fail in a very slow and frustrating manner popping up only now and again, as other posts have documented, I did not risk driving driving mine when I had it and ordered a new sensor. Though from what I recall more prominent when engine is warm.


Could be immobiliser also, but Immobiliser does not flash glow plug light from what I recall.

The Cam sensor errors do not tie up with the starting problems, I've proven that before (and I have already replaced the Cam sensor and there are no Crank sesnor errors).
Using an uncoded key does give the glowplug light flash - I proved it this morning.

Thanks for the thoughts though.
 

AndyP

Member
Haha,

I’m due to visit your area in a few months (before Christmas). I’m more than happy to drop in and grab your SKC so you can code it yourself with your VCDS or even do it for you. It’s a quick process, no more than 10 minutes.

Kind regards,

Tom

Can't believe I let you escape without doing it last time! Yeah, just let me know, I'm at home 99% of the time now and there's always a cup of tea waiting ....
 

depronman

Member
Andy
If you want to disable the immo even on a temporary basis then let me know I can do this via post you send me the ecu and read out the skc code and set the immo to off
Paul


Sent from my iPhone using Tapatalk
 

Un4tural

Member
The Cam sensor errors do not tie up with the starting problems, I've proven that before (and I have already replaced the Cam sensor and there are no Crank sesnor errors).
Using an uncoded key does give the glowplug light flash - I proved it this morning.

Thanks for the thoughts though.
Good to know, proves my memory wrong, could have sworn it was just the key that lights up for immobiliser!
 

timmus

A2OC Donor
Hi Andy,

Can you confirm that the immobiliser light in your instrument cluster is working (it's at the 3 o'clock position within the rev counter)? When you first turn the ignition with your programmed key, does the immo light illuminate and then extinguish? When you turn the ignition with your spare, unprogrammed key, does the immo light flash?

Cheers,

Tom
 

AndyP

Member
Hi Andy,

Can you confirm that the immobiliser light in your instrument cluster is working (it's at the 3 o'clock position within the rev counter)? When you first turn the ignition with your programmed key, does the immo light illuminate and then extinguish? When you turn the ignition with your spare, unprogrammed key, does the immo light flash?

Cheers,

Tom
Hi Tom,
Yes, exactly that happens.
 

66Beetle

A2OC Donor
Hi Andy,

Can you confirm that the immobiliser light in your instrument cluster is working (it's at the 3 o'clock position within the rev counter)? When you first turn the ignition with your programmed key, does the immo light illuminate and then extinguish? When you turn the ignition with your spare, unprogrammed key, does the immo light flash?

Cheers,

Tom
Tom,

Tried to Text and Call you today on the Mobile Number you gave me 2 years ago. Text Not Delivered. Number Not Recognised. Went round to your house about 18:30 - 19:00 ish this evening. Put a Note through Letter Box. Are you around at the moment please ? Looking to get our A2 Plugged In to Diagnose a Running Fault. Had been to Screwfix on Caton Road. Stopped by Roadworks at Crook of Lune. Engine started running “ lumpy “ and Amber Emissions Lamp kept Flashing. Seemed to improve a bit on the way home.

Regards,

Steve
 

AndyP

Member
Well I may have possibly solved this problem and it may be embarrassingly simple. After a few weeks of this problem coming and going and much reading of error codes etc., it would appear that Cam Sensor errors were becoming more frequent. Unfortunately the ECU doesn't preserve the time or frequency of the errors - that would help enormously. Anyway, I decided to replace the sensor (again) and this time I got a Febi part. On the monring the sensor arrived the starting problem returned and just for once when I didn't have to go anywhere in a rush. So I had time to disconnect the sensor, then the engine would start, so it seemed like the cause. I replaced the sensor and it started first time and has continued to do so - fingers crossed.
 
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