The SA 2.6i Microbus thread

[silverbullet]

I appreciate that this is pretty obscure but here goes...broke down in the 2.6 SA on Friday, had to be recovered thought I had fixed it with a new coil over the weekend so used it Monday ok and then this morning it ran for all of 10 seconds then died and wouldn't restart.
Symptoms are:
Sudden failure to start after a 75 mile journey; would eventually start but die if more than 1200 rpm; could pull away and drive but would soon stall again; restarted after standing 2 hours (stalled once but restarted again to turn round for loading onto recovery truck)
The ignition is a Hall-effect trigger (I think) type Bosch dizzy, the coil is a non-TCI generic VW modern "block" type (loom has a slight mod to remove multi-plug, it has 2 terminal posts instead like a Golf or Passat). Ignition was modded/repaired soon after import in c.2005 by a SA ex-pat mechanic in the Basingstoke area.
It also has what is described by etka as an "altitude sensor" on the bulkhead, with a vacum hose to the inlet manifold and a multiplug (3 pin) Not sure if it should have a TCI or not, etka not clear but it's run ok for the last 6 years as it stands.
Where to start? Suspect the trigger in the dizzy? Trying not to tear my hair out but it is my daily driver and everything else is broken, apart from the Mrs' trusty Sharan...
Help please!

[Aidan]

looking at ETOS hall sender is on end of camshaft not in disi, disi looks simple. Do you have an ignition amplifier module on yours - switch unit TCI -17S 905 351 B or suffix A - the equivilent on our systems are often the culprit in situations like this

[bigherb]

First you need to establish what you are losing, spark or fuel! First when the engine wont start remove the HT coil lead out of the distributor hold it close to an earth point and crank the engine to see if you have a spark, it's easier and more accurate if you get one of these just insert it between the spark plug and HT lead it flashes when there is a spark. Halfords used to sell them as well.
http://cgi.ebay.co.uk/Spark-Plug-HT-tes ... 4aa9796198" onclick="window.open(this.href);return false;

[silverbullet]

looking at ETOS hall sender is on end of camshaft not in disi, disi looks simple. Do you have an ignition amplifier module on yours - switch unit TCI -17S 905 351 B or suffix A - the equivilent on our systems are often the culprit in situations like this

AIdan - I looked at that particular etka diagram (if it's the one I think you mean) and it shows the V6 engine There's nothing on the end of R5 head apart from the dizzy poking out towards the centre of the engine bay, behind the last/first spark plug.
It doesn't have a TCI but since it's been modified it may not have the correct dizzy either, in which case things get a lot worse from here. It has either an optical or Hall sender inside.
Time for a picture or 3 and some part numbers - more later.

[silverbullet]

Here you go:
The general arrangement, the "altitude compensator" is to the far right of the coil (cruise relay and diagnostic socket in between) and the 3 wires from the distributor join the loom and head in the direction of the ECU, under the rear bench. Maybe these have mapped ignition, hence no TCI?
Note: old picture with suspect coil fitted, replacement identical.

Bosch distrubutor part number

Inside the distributor:

[bigherb]

Looks like the standard setup, the TCI is built into the coil.

[silverbullet]

This coil does not have a TCI module, it's just a basic dry coil. I should know, I fitted the replacement! SA's are nothing like German-built vans. The EMS doesn't even use a MAF sensor for a kick-off, so it's not like any EFI WBX at all.

[silverbullet]

After trawling a LOT of online lists and cross-referencing to double check, I have found out that the mystery module top right is a MAP sensor - for a 92-95 Audi 80 1.9TD 1Z !!! This is how the engine senses load. Distributor is generic VAG recon from the Bosch part number 0 986 237 678 (0 237 522 015).
Managed to source both from trade suppliers on £bay for less than the cost of the dizzy alone via LMF...
Trying hard not to think about the 22S Motronic ecu...to awful to contemplate if it's getting twitchy.

And yes that CV boot has had it

[silverbullet]

Well it wasn't the MAP sensor at fault and the dizzy that came has the wrong trigger unit (meant for a TCI, and this one isn't)
Back to google with the part number of the Bosch trigger unit now...should have known better than buying a generic part off £bay
Hall sensor in the Bosch has part # 1 230 329 038 but I can't find it online...

[Aidan]

according to etka your original disi 034 905 205H obsolete replaced by 034 905 237 AX which is £85.43 plus vat from VW - it might be worth checking - I think the Hall Sender shown as on the end of the 6 pot is what is in your unique disi, found one other link in Etka for that disi 1986 Passat engine code SK which doesn't show anywhere else, so it could be a mistake in Etka/Etos
the original coil was unique though that new coil pack -ignition transformer is fairly widely used now
no info on the rest of the engine management bits - iluus 906-10 only gives the ecu info none of the other parts like the MAP sensor in version 7 or ETOS which shows the full picture but no detail
nightmare

[silverbullet]

Yup, it's a nightmare alright...but I got an email from syncrohospital this morning and Stuart hade the same symptoms with a 2.6i syncro back in December. TPS pot was the culprit, they opened it up and improved the brush tension on the contacts as a spare wasn't available and it's been ok ever since.
So that's what I'll try today and get it re-timed. Somehow.
That illustration in etka is definitely wrong (but the part numbers might be correct)
I have just bought a manual for the later Audi 80 that includes 2.3 and 20v engines so should tell me most of what I need...

[silverbullet]

Here's the TPS, with a nice friendly German VAG part number (Golf Mk 3)

With the aid of a punch to pop out the rivet tubes and some matchsticks to lift the snap tags (broke one off, whoops) I find this inside:

The matchstick is pointing to a part of the carbon track that corresponds to about 1/3 throttle, and the white ceramic of the backing is showing through...I tweaked up the contact fingers about 0.5-1mm as the pressure was non-existant, but it runs just the same.
Time for a new throttle pot.

[Aidan]

I said it was just like no afm on a digifant symptom, is the golf one still available ?

[silverbullet]

Looks like it's still available as it also fits other models - Stuart tells me he can get them in SA too but they are a bit dear. I'll try TPS first thing Tuesday before sending a shopping list to Pretoria...

[silverbullet]

044 907 385A is still a good part number at VW and it's a whisker over £50 + vat
The bus has got to have one, so if this fixes the fault I'd better have a spare before they go NLA...

From my conversations with stuart at syncrohospital, it turns out there a early (mine) and later engine management systems for the 2.6i, both unique to SA. They are more advanced that I realized as all the ignition is handled by the ECU (the TCI is built-in) and the distributor is only there to put the spark to the relevant cylinder i.e. it has mapped ignition curves.
The use of a MAP sensor over a MAF means no flow restrictions so better ultimate power output, important at higher altitudes in SA when thinner air means big losses in performance.