It Begins: The S3 1.8T into my '85 Mk2 GTI

**GOLFBALLS** · 10-01-2014, 02:32 PM

Wow it's been a while!

Bad news.

I have no power getting to the ECU for some reason so the car is paralysed.

Anyone able to help with possible causes ie: relays, etc???????!!!

**sports racer** · 11-01-2014, 10:28 AM

Why not take this opportunity to bypass the ignition switch and run a separate +ve wire to the ECU via a hidden switch in the cabin. Run it to a +ve connection that only gets power when the ignition is on (make sure it's fused). That way if you leave the car with a mechanic you can leave the ECU switched on because it will only come on with the ignition turned on. When you park at work/home/naughty ladies club you hit the switch and no-one can drive off in your car.

I had a push on / push off switch mounted in the foam padding under the top of the dash. You couldn't see it but you could feel it if you knew it was there.

If you decide to produce this commercially and make millions I want 50%.

Cheers

Paul

**Jarred** · 11-01-2014, 12:05 PM

Originally Posted by sports racer

....
I had a push on / push off switch mounted in the foam padding under the top of the dash. You couldn't see it but you could feel it if you knew it was there.
..

Sneaky. I love it!

**golfmeup** · 23-02-2014, 01:26 PM

Wade, loved reading this from start to finish again!
Your build is an inspiration for my planned 1.8T build later this year.

I think I'll be going for a milder AGU setup however as this will be a daily driver.

So the Qpeng is out of the question then!
I have a lot more research ahead of me!

**GOLFBALLS** · 11-03-2014, 08:03 PM

Hi again fellas. Jeez its been a while since i checked in here!!

I've been scratching my bald-ass head for the last 6 months trying to figure out whats causing a massive misfire issue when the engine is under load pulling from low revs with hard throttle bursts...

Coincidentally, When the thing cut out that day my tuner said the ECU wasn't getting any power. He couldn't trace why, but he made a better earth which improved it , then he wired up a separate power supply to the ECU.

This got the car at least running again. So i asked him what he thought the heavy misfire could be, to which the answer was "what misfire? The thing runs great".

Somehow the new earth & power supply had fixed the misfire - but only temporarily. It came back later on that day...

So, I have a pretty good idea what it is...

stay tuned kids

**sports racer** · 14-03-2014, 12:00 AM

Fixed?

**GOLFBALLS** · 14-03-2014, 02:42 PM

Nope.
A while back i got some water down in the fuseboard which caused the wipers to go nuts. I checked the fuel pump relay the other day and there was some pretty gnarly corrosion there and i thought i'd found my problem.
Anyway, roccodingo sorted another CE2 fusebox for me and after putting it in last night it has done four fifths of f#@*all.
Car is still misfiring and carrying on under load.

Then i disconnected the coilpack harness and found some cracked wires. I tried to fix them up and put a full set of coilpacks in just to make sure.

I'll test drive it tonight...

**sports racer** · 14-03-2014, 05:12 PM

There's an old trick to see if your misfire is caused by faulty/worn sparkplug leads. Have a look under the bonnet in the dark with the engine running but no lights on, not even a streetlight. A dark garage works best. In the dark it's pretty easy to see any stray sparks jumping from the leads to something else.

**GOLFBALLS** · 15-03-2014, 12:58 AM

Originally Posted by sports racer

There's an old trick to see if your misfire is caused by faulty/worn sparkplug leads. Have a look under the bonnet in the dark with the engine running but no lights on, not even a streetlight. A dark garage works best. In the dark it's pretty easy to see any stray sparks jumping from the leads to something else.

yep a good trick! I'd forgotten that one. Obviously there's no spark leads here but you can probably do the same with a split coil pack harness.

BUUT, ITS FIXED!!!!

After months of frustration its finally back to it's bangin' old self!

I changed the coil packs and taped up some of the suspect wires at the same time so i dunno which it was that was causing the issue, but right now i dont care!!

One difference is the violence of the off-throttle boost purging. I think its just because i've deleted all the stupid breather tubes, vacuum pipes, pcv stuff etc so there's nothing to absorb the pressure from the system (i havent put a catch can in yet, its just going into the air!!). But more on that later...

So back for a remap soon.

Thanks for the suggestions ppl

Now i can crack on with the engineering certificate...