ECU Garage Switch

jonjo

Member
Theoretical question - Is it possible that a garage could switch out your ECU leaving your car with an intermittent fault they couldn't repair themselves?

Anyway of knowing?
 

Howey

Member
Very much doubt it!

Have you got a spare key that the garage has had no access?

Try it and see if engine still runs without any immoboliser light on dash that would prove it!
 

Howey

Member
The battery is irrevalant as your testing all your keys are still coded to your ecu which i believe would be impossible if the ecu has been swapped (happy to be corrected mind)
 

audifan

A2OC Donor
It is only the top part of the key ( contains the ID48 chip ) that you are testing. If the car starts then immobiliser could be on or off as it could be the original correct ECU or the immobiliser could be coded off on a replacement ECU or the replacement ECU has been coded to the car so the immobiliser works....... A lot of work to "induce" faults if that is what has happened. Why do you suspect foul play?
 

jonjo

Member
Tried the spare key, I had put a fresh battery in it last year. it wouldn’t unlock the car but was fine to start it and then lock it. I’m guessing that key *has* to unlock for the immobiliser to read it or is it on the ignition barrel on these?

Only possible foul play because I overheard someone at the garage getting excited about the a2 and saying “hasn’t x got one like this” then being shut down by the manager pretty quickly/abruptly. Since I left it with them and had an “ecu repair” it’s had trouble starting. They have pointed at everything else except the ecu. I just wondered for peace of mind that they are trustworthy then I could cross that off the root-cause list.

Fuel filter, plugs, plug relay and diesel bug have been checked/replaced. Tandem pump drain back and starter motor are on the to-do. The latter was replaced last year. A kind member is sending me a cam sensor and I may be getting an ecu from another kind member at some point.

I know a few members are having this problem.

If I work out how to get a vid up I’ll post the slow start tomorrow.
 

audifan

A2OC Donor
Possibly the tandem is internally worn allowing the fuel to drain back to the tank. Another possibility is the injector loom has aged and now either the wiring is crusty giving resistance or the terminals have become loose on the injectors.

The immobiliser has nothing to do with the keys battery as the ID48 chip lives in the upper half that contains the key blade. The pick up for the immobiliser is in the ring area around the ignition switch.

Suggest having a full VCDS scan done on the car, although even that will not tell all faults due to not everything reporting to the computers.
 

jonjo

Member
Thanks @audifan I will add the injector loom to the checklist. Would I expect other symptoms if the injector loom was failing, like misfires or rough running? It's relatively smooth once warm.

VCDS threw up bad Plugs and Plug Relay which we have switched out with no change.

The red herring is that the start problem only came after the garage repaired the MAP sensor harness and the subsequent "damage" that had caused to the ECU.
It is possible it's co-incidence or poor timing.

To check fuel drain back, do you know if it is hose 1 or 2 (or neither) that I should temporarily replaced with clear hose for monitoring?...
1638967810643.png
 

audifan

A2OC Donor
Hose number 2 in the diagram is the fuel feed line. This is the line that will drain back to the tank if the tandem is failing. Pipe number 1 is the excess fuel return line.
 

kp 115

Member
Tried the spare key, I had put a fresh battery in it last year. it wouldn’t unlock the car but was fine to start it and then lock it. I’m guessing that key *has* to unlock for the immobiliser to read it or is it on the ignition barrel on these?

Only possible foul play because I overheard someone at the garage getting excited about the a2 and saying “hasn’t x got one like this” then being shut down by the manager pretty quickly/abruptly. Since I left it with them and had an “ecu repair” it’s had trouble starting. They have pointed at everything else except the ecu. I just wondered for peace of mind that they are trustworthy then I could cross that off the root-cause list.

Fuel filter, plugs, plug relay and diesel bug have been checked/replaced. Tandem pump drain back and starter motor are on the to-do. The latter was replaced last year. A kind member is sending me a cam sensor and I may be getting an ecu from another kind member at some point.

I know a few members are having this problem.

If I work out how to get a vid up I’ll post the slow start tomorrow.
Did you have it scanned with VCDS at all prior to this garage visit?
As this should show ecu ID I believe.
Hope that helps
Keith.
 

jonjo

Member
Did you have it scanned with VCDS at all prior to this garage visit?
As this should show ecu ID I believe.
Hope that helps
Keith.
Sadly not that I would have access to...the garage has their own VCDS. Nice idea though, I'll see if I can contact the previous owner.

The spare key (that they didn't have access too) did work but they could have removed the immobiliser coding as part of the "repair". The key/car symbol still shows on the dash during startup, I'm not sure if that would show if it had been decoded?

I think chances are slim they switched it. The main outrage is the ECU repair cost of £375, more than a second hand ECU! and created more problems! 😬
 

audifan

A2OC Donor
Not trying to rub salt.. Did you post here with the problems first before you went to the garage. So I am I correct in saying they have repaired your ECU or they have replaced the ECU. If replaced demand your original one.

You REALLY NEED to have a full VCDS scan done now to highlight any issues.

This goes back to my statement about the first 4 things to get as a new OR existing owner before upgrades.
At least 2 fully working remote keys.
A minimum of VCDS Lite on a laptop and a cheap KKL cable from ebay or a Gendan cable.
A good electrical test meter preferably with loop clamp.
The owners manual as it contains important information and answers most common questions.
 

Howey

Member
Sadly not that I would have access to...the garage has their own VCDS. Nice idea though, I'll see if I can contact the previous owner.

The spare key (that they didn't have access too) did work but they could have removed the immobiliser coding as part of the "repair". The key/car symbol still shows on the dash during startup, I'm not sure if that would show if it had been decoded?

I think chances are slim they switched it. The main outrage is the ECU repair cost of £375, more than a second hand ECU! and created more problems! 😬
If the key is known to the car and coded to dash/ecu, the immo will behave as normal, however an uncoded key would start the car as normal but immo light will continously flash

Cover key in tin foil so the dash cannot report a known key is present (and disarm immo), car should then start for 2 seconds then stop
 

Howey

Member
Scratch that just tried that and its unreliable, cast iron way would be for you to take key blade out and use pliers or better still contact jim mann with a picture of your key and buy a "surf" key which will just be a basic key. telecomman@hotmail.com

Great guy and superb service!
 

kp 115

Member
Sadly not that I would have access to...the garage has their own VCDS. Nice idea though, I'll see if I can contact the previous owner.

The spare key (that they didn't have access too) did work but they could have removed the immobiliser coding as part of the "repair". The key/car symbol still shows on the dash during startup, I'm not sure if that would show if it had been decoded?

I think chances are slim they switched it. The main outrage is the ECU repair cost of £375, more than a second hand ECU! and created more problems! 😬
Get a price from ECU testing to compare normally around £170–£200 & lifetime warranty!
I’ve used them on a couple of cars with no problems
(ecutesting.com)
 

jonjo

Member
@audifan those 4 items are now the highest priority on my list!
They should be on a bumper sticker for new club members!

Fuel Drain Back - Stuck at the hose clamp on one end...suspect VAG 1921 is needed, the local garage thinks the lugs snapped off the clamp. My last visit there!

ECU - thanks @kp 115 for the ecutesting.com link, had a chat with them and they can take the ECU for £45+VAT and £20 Return postage, check VIN stored and investigate faults in a 3 day turnaround so this is looking like a decent/viable option.

Starting this morning was brutal, half way between start and stop for around 7-8 seconds.
 

audifan

A2OC Donor
The VAG tool is the best way to remove those clamps and equivalent ones can be bought on that auction site, but with CARE pliers or mole grips can be used. If the lugs have gone you will need to replace the clamp(s). Disconnect the line at the tandem pump not where is joins the metal fuel pipe.

Can you park the car facing down hill? If so that can slow down the drain back to the tank. You could still have a combination of leaking tandem AND injector loom faults. Unfortunately neither will show up in a scan. You could remove the rocker cover to access the injector loom and unplug each injector then CAREFULLY squeeze the loom connectors to make a tighter connection onto the injectors. Just make sure the gasket for the rocker cover is not damages and follow the instructions to refit it including the torque settings. That said by the time you have gained access to the injector loom and cleaned the connections and tightened them you may as well replace the loom. All costs money so depends on finances as a tandem is not cheap either.

Regarding the ECU, yes that company should be able to help you. Although if you have someone near you with good knowledge that can obtain the security code from the car then program a replacement ECU that may be an alternative. Even if you just get an ECU with the immobiliser turned off- not the best way but can be cheaper and then get someone to match the codes and reinstate the immobiliser at a later date.
 

jonjo

Member
For the hose, are you suggesting to leave the original hose connected to the metal fuel line and couple in a bit of clear, or just disconnect the tandem end first?

It is an expensive problem to hunt for, I'm hoping the cheaper options will turn a culprit first!
Ideally someone on here would be stripping an ATL with known good tandem/loom/fuel housing/starter etc.
There is a conversation open with a kind member here about a potential ECU but I suspect they are snowed under at the moment.
 

audifan

A2OC Donor
Personally I think fitting a used tandem is false economy. The work it does justifies a new replacement and a quality OEM metal gasket that has the extra tracts of blue silicone.

Disconnect at the tandem end and then either remove the hose completely and replace with clear pipe or couple a piece of clear between the tandem and the top of the rubber fuel pipe.

LUK pump and gasket is the direct swap where the better Bosch pump requires the use of an additional spacer that needs modifying to allow the ASV to clear the bigger Bosch pump.

Injector loom £84 here..


Tandem pump £168 here...


Probably others these are for an idea of prices. Darkside are very good and have used them myself before.
 

kp 115

Member
Personally I think fitting a used tandem is false economy. The work it does justifies a new replacement and a quality OEM metal gasket that has the extra tracts of blue silicone.

Disconnect at the tandem end and then either remove the hose completely and replace with clear pipe or couple a piece of clear between the tandem and the top of the rubber fuel pipe.

LUK pump and gasket is the direct swap where the better Bosch pump requires the use of an additional spacer that needs modifying to allow the ASV to clear the bigger Bosch pump.

Injector loom £84 here..


Tandem pump £168 here...


Probably others these are for an idea of prices. Darkside are very good and have used them myself before.
Same here & glowplugs in 1 place far cheaper than tps or dealer.
 
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