1.6 diesel to 1.8 8v carb conversion help needed

The headlight loom came with the wiring for the coil, a coil, and ignition module so its just the other bits  I need to sort

rubjonny said

ah ok that makes sense then, you just have the headlight loom which doesnt really help with the engine side of things

the diesel loom is fine just needs a couple tweaks mainly to add coil power and rev counter to coil if you want it, plus sensor stuff above

that wont include the fusebox wirign to the coil though unfortunately, thats just the engine bay side of things.

you'll need a good ignition live for live side of coil, factory its D/23. for the rev counter that comes from D/26, on the diesel loom its in the headlight loom to go to the alternator with the blue wire.

If the headlight loom isnt going to be sold on you could get a sharp knife and cut out the rev counter pin and swap it over to the engine loom. likewise you could pinch one of the larger pins to re-use for your coil power

Could I use the old glow plug live to power the coil?

rubjonny said

that wont include the fusebox wirign to the coil though unfortunately, thats just the engine bay side of things.

you'll need a good ignition live for live side of coil, factory its D/23. for the rev counter that comes from D/26, on the diesel loom its in the headlight loom to go to the alternator with the blue wire.

If the headlight loom isnt going to be sold on you could get a sharp knife and cut out the rev counter pin and swap it over to the engine loom. likewise you could pinch one of the larger pins to re-use for your coil power

rubjonny said

that wont include the fusebox wirign to the coil though unfortunately, thats just the engine bay side of things.

you'll need a good ignition live for live side of coil, factory its D/23. for the rev counter that comes from D/26, on the diesel loom its in the headlight loom to go to the alternator with the blue wire.

If the headlight loom isnt going to be sold on you could get a sharp knife and cut out the rev counter pin and swap it over to the engine loom. likewise you could pinch one of the larger pins to re-use for your coil power

you would have to re-terminate it to fit D/23, or maybe wire it to a relay above the fusebox. its pretty thick though which makes life difficult when trying to splice

another way to do it is fit a 17/18/100 relay in slot 2 then spade N will be live with the ignition.

If you use the glowplug wire it means you wont be able to use the carb heater, but tbh you'll probably be ok without. a lot of guys shave them down, plus they only work while engine is cold.

For the rev counter you could re-purpose the red/black for the fuel cut-off valve. either depin it or just cut and splice it to a wire cut out of the old headlight loom plug as I mentioned earlier

or if you re-fit the diesel headlight loom cut the red/black off the 2 pin near the battery and run it to coil negative instead that'll work direct no messing

Would I have been better off not changing the headlight side of the loom? I could put it back and then I don't need to add the brake light bits. Because the colil wiring was connected up with the headlight loom (via the battery negative I assumed I needed to change the whole lot!

yeah changing the headlight loom doesn't really help with the conversion, but before you pull it out again check it over. keep it if better than the diesel one, if worse then put the diesel one back in

This sounds like the easiest way but I've done a search on 17/18/100 relays and it didn't come back with anything, do you have a link to one so that I can make sure I get the right thing?

rubjonny said

another way to do it is fit a 17/18/100 relay in slot 2 then spade N will be live with the ignition.

Sorry, looked at your post again do you mean either a 17, 18 or 100 relay? there is already a relay in slot 2 (no 60) but this is redundant as its for the glow plugs. Where is spade N? and also does the coil need a ballast resistor?

I have hunted around for new 17, 18 or 100 relays but I can't seem to find anybody who sells new ones, any ideas?

rubjonny said

another way to do it is fit a 17/18/100 relay in slot 2 then spade N will be live with the ignition.

This might help to find spade N
https://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=electrics_2%2Ffuze-box-wiring-layout_2


Search Vw 17 relay or 18

Couple I found…

https://www.ebay.co.uk/itm/VW-AUDI-RELAY-NO-1-15-17-PART-NO-171906383-311963141B-171937503A-CHOICE-X1/153459439160?hash=item23bae53638:g:MUsAAOSw-ghb2Zb~

https://www.ebay.co.uk/itm/VW-Audi-Seat-Skoda-No-18-Load-Reduction-Relay-Part-Number-191937503/270914088716?hash=item3f13bcef0c:g:Kq8AAMXQsmFRbqAv
 

yeah its the x-contact relief relay on a mk1/2/3/4/5/etc golf. the newest version is 644 in mk6 era cars.

sort of thing you can pinch out of a VW down the local scrappy, they all have one somewhere.

spade N is where the glowplug wiring is plugged in now, on the carb its used for the inlet heater and injection engines often used for fuel injectors etc.

So you need an X relay slot 2, leave glowplug wire where it is, crimp a spade on it and pop to coil positive jobs a goodun.

for rev counter either use the diesel headlight wiring and move the old red/black wire for W terminal on alternator to coil negative or find the old red/black wire for the diesel fuel cutoff in D/15 and move it over to D/26.

The small pins are tricky to pop out, theres a relatively cheap tool or you could chop the old diesel headlight plug up for donor pins, or you can buy new pins even if you have a decent crimp tool.

Slowly making progress, engine in, all sensors and other electrics connected up, …..

But I seem to have hit another snag! I have, as suggested used the pre heater circuit with a 100 relay to provide switched power to the coil. I have two other wires that need to be connected to the coil, a black which I thought needed to be connected to the coil negative and a green which, from what I have found on-line needs to be connected to the coil positive, these both go to the control unit.

If I connect them up in this way, when I turn the ignition with a spark plug tester on the centre coil lead, I get nothing.

If I connect the green onto the negative with the black - which I'm sure is wrong -I get a spark at the coil centre lead, but this is a modulating signal so logically it the tacho signal. What I can't understand is why I can pick up a tacho signal but not a constant if I wire it up correctly, could the ignition module be faulty or am I just doin g something really stupid?




 

black is the positive for the coil, to + or pin 15. red/black from the fusebox goes on the negative side for the rev counter.

then you should have an ignition module and wiring loom that drops on top. this has a black wire to the positive and a red/black or green wire which goes to the negative side. Then theres a 3 pin plug to dizzy, and a single ring terminal to battery negative

Black is the switched live right? I don't have that because I'm using the old diesel wiring so I am using the pink/white (diesel pre-heater)  as a switched live. For the moment I'm not bothering with a rev counter.

From the ignition module wiring loom I have a black which is currently on the negative side of the coil so I will put this on the positive side and I have the green on the positive side which needs switching to the negative… I will give that a go.

Thanks, will let you know how I get on


 

rubjonny said

black is the positive for the coil, to + or pin 15. red/black from the fusebox goes on the negative side for the rev counter.

then you should have an ignition module and wiring loom that drops on top. this has a black wire to the positive and a red/black or green wire which goes to the negative side. Then theres a 3 pin plug to dizzy, and a single ring terminal to battery negative

right so the pink/white is the live from fusebox to coil positive, swap the ignition loom wires over and you should be good to go