Need advice from the forum sages

[MarrV]

Sorry to hear you still have problems with your engine,

but this is confusing:-

Vento Haynes manual does not have ignition coil easily labelled, only glow plugs...

bold by me =

(glow plugs only on a Diesel, so you won't find an ignition coil on that diagram )

I know, which is what is so damned annoying. The whole manual has both petrol & diesel through it, but when it comes to wiring it only has the diesel ignition system wiring, the ignition coil for petrol simply is not there. Done some googling/reading and it seems it was an oversight by Haynes in 3097.

Which is just sods law.

The wiring diagram is also a newer type in that manual, think they were trying to make it easier to follow. Either way, working it out.

Ghost - I assume this sort of issue is not common - the van starting one day & not the next. And it is most likely a symptom of something else being wrong?

[ghost123uk]

Ghost - I assume this sort of issue is not common - the van starting one day & not the next. And it is most likely a symptom of something else being wrong?

It's not really uncommon. Intermittent poor starting is unlikely to be anything like timing etc as that won't have changed since the last time it ran. One just has to be methodical.

In order :-

Is it turning over fast enough? (low battery voltage, bad connections on the heavy starter circuit wires, poor starter motor)
Is there a good spark at the plugs?
Is fuel reaching the carb?

Once you have satisfied that the above are all correct, it should run. As I say, stuff like valve clearances, timing, etc won't have suddenly changed by themselves. The most common cause (as above) is the motor not spinning fast enough, low voltage for whatever cause will result in this and also rob the coil of enough juice to provide a nice fat spark.

[MarrV]

Is there a good spark at the plugs?

This is the issue at the moment, fuel is ok & turning over it fast enough.

The timing was me just being paranoid. I know it is fine.

The spark is white, not blue, and seems to be pretty crappy. Which is why im going to go check ignition coil and clean spark plugs now. And been checking all the wiring.

When this damned van works will bring it to a meeting and be ribbed im sure for taking such a long time to fix easy issues

[ghost123uk]

If you suspect the spark, if it were I, I would find another known good coil and ignition amp to borrow and substitute (one at a time) to see if that sorts it. Then, if that doesn't do it, maybe do the same with the hall sensor in the dizzy too. These parts can be got from T25 breakers on here cheap enough. Don't forget the condition of the cap and the leads too

[MarrV]

If you suspect the spark, if it were I, I would find another known good coil and ignition amp to borrow and substitute (one at a time) to see if that sorts it. Then, if that doesn't do it, maybe do the same with the hall sensor in the dizzy too. These parts can be got from T25 breakers on here cheap enough. Don't forget the condition of the cap and the leads too

Leads seem to be in good nick (HT leads) looked at them enough when trying to sort out the timing issue before

*E D I T* Did resistance test on ignition coil, found 15-1 to be 1.3 ohms 15-4 to be 3,420 ohms.

Haynes has it listed as ok (2.4k to 3.5k assuming it is a green sticker). The following issue being that the coil I have in front of me is for a t25 engine, but I do not have a t25 engine.....

I think though the general condition of most parts on this engine will be considered middling to poor (gunge everywhere doesnt help), we know the gear box has recently been "fixed" thats about it.

As for parts to borrow, I think earlier in this thread we asked if anyone was near but got no responses.

Tracing wiring I have a blue/red wire from 15 (+ve) on coil going into a black box marked 12v (pic here). This is not present on Haynes diagram. Please see this pic for how my coil was wired before I removed it.

So is this 12v black box linked just a 12v relay and the N41 (TCI unit) in Haynes the ignition amp? If so think time to find some breakers as you said

[ghost123uk]

The ignition coil is my prime suspect currently, measured resistances across 15-1 & 15-4. 15-1 was around 1.3 ohms, but 15-4 was 3,420 ohms. I believe that the later is meant to be far higher (11-18k)

From our wiki =

Ignition coil - Green (Later type 1986-90) with pin type fitting - most common type for late engines.

VW No. 211 905 115 D Bosch unit with green label. Matches setups where Distributor cap and leads have PIN-connectors.

Test data. Primary resistance [between terminals 1 & 15] - .5Ω to .8Ω Secondary resistance [between terminals 1 & 4] - 2.4kΩ to 3.5kΩ

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ignition coil - Grey (Later type 1986-90) with pin type fitting - extended servicing type.

VW No. 191 905 115 A

Bosch unit with grey label. Matches setups where Distributor cap and leads have PIN-connectors.

Test data. Primary resistance [between terminals 1 & 15] - .6Ω to .8Ω Secondary resistance [between terminals 1 & 4] - 6.9kΩ to 8.5kΩ

I measured a spare (new) coil I keep and I got 0.6 Ohm and 3.42K Ohm, so I reckon your 1.3 Ohm reading indicates summat out of tolerance.

I would for sure be trying a new (proper spec) coil. I am thinking that coil might be for either points type ignition, or a "ballast" fed system (which ours isn't)

However I am struggling to find specific resistances for the ignition coil (not helped by the ignition coil has a distinct lack of helpful markings, only that it is a Bluetronic Electronics Ignition coil for a 12v system with 8051 482 stamped on the bottom).

Can't find any info on that

[ELVIS]

Have you taken earth strap off NS head and cleaned body,engine and terminals on strap?

[ghost123uk]

Have you taken earth strap off NS head and cleaned body,engine and terminals on strap?

I know it's now a very long thread, but he has an inline 4 Golf type motor in his van.

[ghost123uk]

Tracing wiring I have a blue/red wire from 15 (+ve) on coil going into a black box marked 12v (pic here). This is not present on Haynes diagram.

Well that is listed as a 40 Amp Diesel glow plug relay (but someone might have fitted it for some other purpose) You can still see the fuseable link at the bottom of it.

The basic ignition system on the earlier Golf/Scirocco/Passat is the same as on our post 85 vans. Get a proper spec coil and then remove any extraneous wires, relays etc and just wire it up as per original.

[ghost123uk]

In reply to your PM

Will do as you said and get new (right spec) coil & then take out all extra wires.

One thing that seems to be the case with this van is that whoever changed it from its diesel to this petrol engine seems to have followed instructions from multiple sources. Hence left over parts, ignition coil from a t25 petrol on a non t25 petrol engine, extra wires all over the place.

Am thinking your right, just put right parts in & remove all the extra wires. Just need to hunt down this missing ignition coil/system wiring diagram.

Should I also check the TCI to make sure it is for the correct engine, or (as you put it) as "the basic ignition system is the same as our post 85 vans" should it be ok?

Rory/Marrv

The basic ignition system on the earlier Golf/Scirocco/Passat is the same as on our post 85 vans. Get a proper spec coil and then remove any extraneous wires, relays etc and just wire it up as per original.

Well I have just been out to look at our 86 Carb Scirocco. It has a green sticker coil that measures the same Ohms as the spare T25 one I have, so that is the same. The TCI unit looked the same, but one was Bosch and the spare I have for our T25 is Seimens. I was so convinced they are the same, I quickly put the spare T25 one on the Scirocco and it fired up just fine, so they are the same.

This makes getting spares much easier at the breakers because you can get them off an 80's / early 90's Passat/Golf/Scirocco which are much easier to find at the scrappy than a T25. Only problem here is you won't be getting "known good", so you could end up chasing rainbows if you are unlucky enough to buy a duff TCI unit (you can measure the coils )

[MarrV]

Ty sorry for questions in PM, that was meant to be mostly just to say TYVM

As for breakers, I assume work through those listed in wiki as a first port of call

[ghost123uk]

Just popped back in for a cuppa

Ta sorry for questions in PM, that was meant to be mostly just to say TYVM

As for breakers, I assume work through those listed in wiki as a first port of call

Nah, most breakers near you will have a Golf/Passat/Scirocco somewhere. Note they seem to charge more for bits off Golfs

E D I T = Many Audi models of that era will have the same bits on them (same engine )

[MarrV]

Been trying local breakers & not having much luck asking for "80's to early 90's passat, golf, sirocco or audi"

Just occurred to me while asking - does the engine volume need to match up for the ignition amp? As in does the donor vehicle need to be a 1.8ltr as well?

P.s. sorry in breaks of replying health tends to be unpredictable

[ghost123uk]

Just occurred to me while asking - does the engine volume need to match up for the ignition amp? As in does the donor vehicle need to be a 1.8ltr as well?

No as long as it is a carb model, not injection, they are all the same (he said pretty confidently )

[MarrV]

Just occurred to me while asking - does the engine volume need to match up for the ignition amp? As in does the donor vehicle need to be a 1.8ltr as well?

No as long as it is a carb model, not injection, they are all the same (he said pretty confidently )

Sweet ty.