1.8T Problems

[mwarrey]

On my way back to South Wales from Cornwall on Saturday and I started to have problems. The car started to stutter a bit (almost like bad fuel). Above 3500 rpm car seemed to be better but still stuttered when applying throttle (fine when off throttle). So I hooked up the vag com and I get this :-

17967 Throttle valve Control Part Fault in Basic Settings P1559 35-00

I tried clearing it with Vag com, but it just kept coming back, tried throttle adaption but this kept coming back with an error.

I managed to get hold of another throttle body (same p\n AEB non dbw) Put this on but get the exactly the same issues. So I am a bit lost now. I suppose it could be another duff throttle body so I will try to get another.

Anyone had this before ?

 

[mwarrey]

Ok, quick update. I managed to get hold of a Ignition control amp to see if that was the problem (as this is quite a common fault I'm told). However, exactly the same...

 

[aragorn]

the fault code indicates the Tb. If changing it for a known good one doesnt help then i'd suspect the wiring?

 

[Broken Byzan]

The amp usualy means it runs on three cyls, normally dropping 3nd first.

Throttle body would have been my guess, have you checked the wiring?

 

[mwarrey]

Hi, I've done a quick visual check at the TB end, nothing obvious. Anyone know where it is likely to fail, or a good method for testing ?

The problem also seems to get worse the warmer the engine gets ?

I tried unplugging the MAF to but the engine starts and dies instantly (even when giving it throttle)

 

[aragorn]

The engine management system uses default values when a component becomes faulty. So if the TB is faulty it will ignore it and use a fixed value for the throttle position, basing its fuelling solely on the MAF and other sensors. Similarly with the MAF unplugged it will use other sensors like the throttle position and RPM to guess the fuelling.

With the MAF unplugged and the TB knackered its simply not got enough data to run, and so it dies.

Craig was getting a very similar error on his S4, and it ran funny and even bacame compeltely unresponsive to throttle input at times. We ended up swapping the PCB in the throttle body for one from another car (1.6 seat or something) and that sorted it.

Might be worth taking the cover off and giving the tracks a clean to see if that helps?

 

[mwarrey]

Thanks for your replies. I already tried cleaning the tracks (and the internals) of my original TB.

 

[auroan]

Have you "adapted" the throttle body to your ecu ?

 

[mwarrey]

As in my original post. I can't get the TB to adapt, the original one or the replacement.

 

[aragorn]

The TB should adapt itself if you turn the ignition on and wait.

You should hear it whirr and click.

 

[auroan]

I though If you introduced a new TB to a car you had to run it through basic settings in Vagcom and this "adapted" the TB to the ECU.

Thats what I mean't with my previous comment. Not it trying to find the 0 position.

 

[aragorn]

Nah, it adapts itself, might just be after the battery having been removed. But either way, you just flip the ignition on and dont start it. After a few seconds you hear the TB doing its adaption cycle.

 

[mwarrey]

Ok, bit of an update I thought I would share with you. After trying a 3rd throttle body, a new ignition module, new set of plugs the problem remained. I had the feeling that this was something to do with the ignition side (rather than fueling) and was starting to think that the throttle body fault code may be a red herring.

After a visit to a local VW\Audi specialist, the next step they recommended was the coil packs\leads. I had been told by a number of people whose opinions I respect that these don't go on the early ones (unlike the later ones which is a common failure). The specialist said that he had never changed one before, but guess what, they turned out to be the cause.

I don't know whether its the leads or coil packs yet as I replaced both. The fault code remains but the car now drives and idles perfectly.

So what have I learnt ? Having VAG COM is useful but it can lead you in the wrong direction. I was expecting to see some sort of misfire fault logged but it looks like the ecu on early cars doesn't log these. Any part can fail, even if its a rare occurance

 

[Broken Byzan]

Mine dropped a coil pack, fortunatley i have spares already so played musical coilpacks till i found out what it was. Mine only missed under high boost/load

 

[aragorn]

How do you mean leads and coils?

The 1.8T doesnt have leads, the coils sit right on top of the plugs in the cylinder head...

It seems that the fault code was a bit of a red herring in this case, however fault codes dont appear for no reason, so there IS something wrong with the throttle body or its wiring. It just wasnt causing your bad idle.

Its quite common for missfires to go unlogged on these engines, however missfire + nothing on vagcom would have suggested an ignition problem immediately.

 

[mwarrey]

The coil packs and leads can be separated from each other (they just pull apart) The rubber part being in effect a very short plug lead.

About 6 months ago I had a leaking rocker cover gasket which had soaked the leads and plugs in cylinders 3 & 4 with oil. I only spotted this whilst doing a routine service. Oddly this had no affect at all on the cars running or idle which I was quite surprised about considering the amount of oil in there.

The coil or lead that was gone was in cylinder 3. This could be pure coincidence but may have something to do with the failure.

A am a bit lost with the throttle body issue. It has now had 3 different throttle bodies. They could all be faulty but thats unlikely. I have checked the voltages getting to it and they are all correct. The engine idles perfectly (I have the original throttle body back on)

I am not disputing the usefulness of VAG COM, I am just saying that it can lead you in the wrong direction. I had a misfire and a fault logged to the throttle body so thats why I headed in that direction. My gut feeling was that it was ignition related and coil pack was one of the first thing I thought about. I was expecting to see a fault code logged about it.

 

[aragorn]

I would dig out the wiring schematic, and check the continuity of each pin on the throttle body plug back to the ECU plug to ensure theres no broken wires.

If its not the TB itself, then it can only really be the wiring i would think?

 

[mwarrey]

Paul, it was Andys VW\Audi in Swansea, very helpful guy. Thanks for your recommendation about Europerformance, I didn't think the car would make it that far!

This morning, out of interest I swapped the lead on the suspect coil and it is the coil thats gone.

I have checked as much as I can on the wiring (I followed elsa). The voltages are all correct, I guess continuity to the ecu is next (but elsa talks about using a test wiring block which I haven't got).

Again I would have expected the ecu to throw up a fault about communication to the throttle body if there was a problem there though ?

The plus side is that I now have some spare coil packs ! If anyone is having similar problems PM me