HELP; strange electrics

[GOLFBALLS]

Last weekend i decided to have a crack at fixing some weird electrical glitches in the GTI. It had headlights not working and some funny earth probs.
After replacing the neg- battery terminal, actually connecting the earth eyelet to the body and replacing some fuses and headlight bulbs its all much better.
But one bloody annoying problem remains. When accelerating, the car used to sorta sputter and lose power breifly at 2750-3000rpm. Sometimes it'd be real bad and jolt and carry on! After fixing the stuff last wkend, its much better, but still slightly has the same prob. It seems to usually happen when the headlights are on, and when the indicator is blinking.
I tried it again last nite.
Rev from 2000rpm up to 3000rpm with lights on - smooth as silk.
Do the same and put the indicators on - ignition shudder city. Its like a power drain
I have noticed the left indicator flashes irregularly.. and my wiper stalk is a bit ****y...
Any help

[moto]

How is it when you turn the ignition on? Any funny events like the tacho kicking up to 2000rpm before the engine fires? Check the current at the fuel pump when you have other things turned on. Borrow a good ecu from someone and see if the problem goes away.

[GOLFBALLS]

Hmm, ok cool.
The tacho doesnt really rocket up at start. It even rarely has the infamous bouncy idle.
I'll def check that fuel pump tho...
Thanks mate.

[Jmac]

Mate run a seperate earth to the ECU. Ive had a few probs with them. I cut the main BROWN wire at the Ecu and ran it seperate to the Cylinder head. Fixed running fault mate, yes they are bad for earths with age, and this sounds like a common earth fault. Check you havent been getting rain into your fuse box mate, this too is a VERY common fault on the Mk2. The gromment for the bonnet cable loses its seal with age and the lets water run down the cable and straight into the fusebox. Had them go green in the Uk with our crap weather, caused all sorts of weird elec faults, really the only fix then is a fusebox or dry in depending how gone it is, and seal that grommet
CHeers
Jmac

[Golf Loon]

Sounds like a good time to get hold of a UK spec ecu mate

[GOLFBALLS]

Great thanks heaps guys, i'll try all of the above and get back to youse all
Loon, you mean my coming QPEng ECU right?? Haha.
Just a dumb thought - it couldnt be alternator related could it? It is very noisy and screams like a cat in a woodheater when cold!

[moto]

mate,
It sounds like you've got a problem with something breaking down randomly.
Irregular missfiring can be caused by not enough fuel (pumps/filter/injectors ), not enough air (airflow meter) or not enough spark (plugs /coil/hall sender etc). It can also be caused by the main earth to the engine being loose (Have you had the starter motor out recently?), knock sensor, oxygen sensor, temp sensor and even the ignition switch.

A few easy things to check: look at the loom behind the throttle body and make sure it hasn't rubbed through(the engine tends to lean on it when it rocks back). Check the insulation of wires around the block. 15 years of heat and oil vapour causes the insulation to crack. Run the engine in the dark and rev it to see if you can reproduce the miss. Load it up in gear and under brakes if necessary. Have someone watching under the bonnet to spot a fireworks display. Check the connections at the starter motor and at the alternator. Some parts of the loom terminate there. If you are getting voltage drop through the starter connections or alternator that might contribute to the problem. Dodgy starter or alternator can give you voltage drop too.

To fix air flow meter or ecu are serious dollars so its a good idea to eliminate the cheaper things first. If you think you're spinning wheels, I'd spend $50 with an auto electrician to get a diagnosis. Speaking from recent experience, I'd do it asap while its drivable because an electrical problem can leave you waiting for a towy and unless you're surrounded by shelves of spares a non starter is especially hard to diagnose.

[GOLFBALLS]

Hey chaps.
I managed to check a couple of things yesterday before it got too dark and started to rain.
There isnt any visible damage to the wiring behind the throttle body, all earth connections to the engine looked fine and the ECU doesnt seem to be getting any water in there either. As the problem isnt totally random (it only occurs at around 2750 rpm) and is linked to the indicators and lights, i have a feeling its either fuse related, and/or voltage drain to the fuel pump, air flow meter or even distributor getting outta sync. As soon as the revs clear past 3000rpm its fine again.
I'll check the fuse box connections for water leaks and voltage to the fuel pumps when i get the chanceand keep y'all posted

[Jmac]

Good onya mate , as an exercise splice into the brown wire at the ecu and earth it and see what it does.
Jmac