1.9tdi accelerator dead, glowplug flashing, engine fault.

[Lordbob]

So....this may be a bit wordy but really hoping someone here is a magician...

Just picked up a Fabia 1.9tdi, 2007 for the missus. Test drive absolutely fine, drove approx 100 miles and no probs then I get a call, the car had broke down. Recovery came, brought it home and as soon as we got it off the truck, it fires up and drives like a scolded cat.

Next day, drive to work early and its fine, get in to come home and she drives half a mile and the coil light flashes, the accelerator is dead and she's on meltdown (the missus) Recovery called, they get there and car starts fine! So she drives home no issues. 

Next day....drives to shops, dies again so it goes to the garage. They pop it on the machine and says throttle body sensor so they replace it. Drives fine until home then fails again, same issue.

I have a Bluetooth and streetwise obd2 reader and neither show faults.

I have changed the brake pedal sensor after reading something on a forum and still doesn't go. 

It has gone from a intermittent fault to continous now. I have had a bit of a root around and I've figured out it's had a new ECU (the one on it has fabia mk 2 in green pen on the back, I'm sure that's not factory spec). The accelerator pedal says polo on it, again not factory spec so obviously the ******* that sold us it had issues before.

It's methodus operandus now is I turn it on, works fine on tick over, try to drive and the revs go OK for seconds, then all over, the no response and the engine goes to just above idle, which must be safe mode.

So my pondery is this, do I a) take it back to the garage b)scrap it and take a loss of about 900 or c) pray. I've had fabias before, we have had the 1.9 pd in other cars and they have been great, which is why we went for this but I don't want to be throwing money in a pit.

Had an mot in April, no issues. Serviced it just after purchase and when we got it, it went brill so I know the engine is strong.

Any pointers much appreciated!

[sepulchrave]

I strongly suspect a wiring issue, probably the engine loom, the core strands get work-hardened and start snapping making intermittent contact as the engine rocks and moves until something important goes and the ECU says no more and puts the car into limp home mode, this mode will usually clear when you switch the car off and back on again and restart it.

A generic code reader simply isn't good enough for diagnosing tricky faults like this, you need access to extended VAG diagnostics so I suggest you find a good auto electrician rather than using garage mechanics.

You could simply replace the entire engine bay loom but that could be very expensive indeed.

Bad luck, but if you find the right firm this may not be that expensive to put right, the sheer mongolism of replacing a perfectly good ECU beggar's belief so you can imagine the scale of the bills the previous owner paid before palming it off on you!

[nige8021]

You really need something better than that streetwise reader, it's just a very basic code reader, something that is VAG specific and gives "live data" that way you would be able to see in real time if the throttle pedal position sensor was giving the correct signals to the ECU, might pay to have a look in this https://www.briskoda.net/forums/topic/262215-list-of-vcds-owners-previously-known-as-vag-com-vcp-owners/  and see if there is someone local to you who would help read the system for you 

 

[Lordbob]

22 minutes ago, sepulchrave said:

I strongly suspect a wiring issue, probably the engine loom, the core strands get work-hardened and start snapping making intermittent contact as the engine rocks and moves until something important goes and the ECU says no more and puts the car into limp home mode, this mode will usually clear when you switch the car off and back on again and restart it.

A generic code reader simply isn't good enough for diagnosing tricky faults like this, you need access to extended VAG diagnostics so I suggest you find a good auto electrician rather than using garage mechanics.

You could simply replace the entire engine bay loom but that could be very expensive indeed.

Bad luck, but if you find the right firm this may not be that expensive to put right, the sheer mongolism of replacing a perfectly good ECU beggar's belief so you can imagine the scale of the bills the previous owner paid before palming it off on you!

Thanks for the reply...I was leaning towards a electrical issue, and i was kinda hoping a sensor how it's got progressively worse. I'll have a look at an auto electrical, I just don't want to spend hundreds more on a car that wouldn't be worth it, rather just scrap it or split it and chance with something else. Lesson learned and all that I guess.

[Lordbob]

25 minutes ago, nige8021 said:

You really need something better than that streetwise reader, it's just a very basic code reader, something that is VAG specific and gives "live data" that way you would be able to see in real time if the throttle pedal position sensor was giving the correct signals to the ECU, might pay to have a look in this https://www.briskoda.net/forums/topic/262215-list-of-vcds-owners-previously-known-as-vag-com-vcp-owners/  and see if there is someone local to you who would help read the system for you 

 

My little Bluetooth one gives live data on my phone app and shows the throttle position going up and down when the pedal is depressed but that doesn't reflect in RPM on the engine. Unfortunately no one is near me on the map.

I'll have a look for a VW specialist nearby maybe.

[Breezy_Pete]

VCDS lite can be used on a 2007 mk2. Get a suitable cable for £10-20 (e.g. this one) and download the free software from ross-tech.com onto a laptop. Minor faff getting it talking to car then really good diagnostic capabilities.

 

Can you ask the garage that said "throttle body sensor" exactly what fault code number they saw, and exactly what they replaced?

 

Edited 24 June, 2022 by Breezy_Pete

[KenONeill]

@Lordbob - Reads like throttle position sensor to me. Particularly with a non-stock used item installed.

[ApertureS]

Another case of garage sees a fault code and just replaces parts.

 

when will these parts changers (I won’t call them mechanics) learn that just because there’s a fault code for part X doesn’t mean part X is the fault. 
 

if a lambda sensor gives a fault saying o2 sensor bank 1 - mixture rich you don’t go and change the o2 sensor on bank 1 do you... you look further into it and find the cause.

 

sorry that you’ve been stung once by a dodgy seller and again by a ****ty garage.

 

you’re gonna need a higher end code reader to start on this journey of fault finding and then you’ll have to go from there.

[logrover]

When i had throttle issues (signal dropping so fabia-2 1.2 went into limp home mode), i removed the electronic throttle pedal and opened it up. I seem to recall it was easy to remove and open, and i then cleaned the contact tracks and "fingers" and made sure they were making good contact, put it all back together and its been good for a couple of years so far.

 

might be worth a go?

 

pics on inside of pedal after cleaning:

[Lordbob]

Thank you all you lovely people so far. I have found a vw specialist in preston its going next week but I'll have a look at the pedal this weekend, as you say it's a cheap and easy thing to look at. I will keep updates coming as soon as I have them.