electrical gremlins

[steveyb]

My 87 gti 16v is suffering from some nasty little probs.
Firstly the fuel pick up pump sometimes wont work when i turn the ignition to stage two (when you'd expect to hear it). Then sometimes it wont work long enough to start the engine or splutters a bit.
 ive found if i turn the key back and forward till i get the correct length of time for the pump to run then it starts as normal. i can always hear relays working but not entirely sure if its the fuel pump relay thats working.

The second prob is when using the drivers side electric window it causes the engine to misfire, only happened a few times but always when the elecy windows are being used. sometimes its stops the window working after the misfire. after leaving the car and turning it off for a bit, then they work again. not noticed this problem when stationary only when on the move.
 Any ideas?

[rubjonny]

if the 2 problems are related I'd say its the ignition switch, thankfully being an 87 its a doddle to change as you can remove the ign housing from the car. assuming its not had the spline adaptor retro fitted.  could be problems are seperate tho, if so I'd start by replacing fuel pump relay then checking the in-tank lift pump is working. if not it will starve the main under car pump of fuel and eventually casue it to die. to check it, pull the plug off the main pump under the car and repeat the key turning tests, you should hear the in-tank pump prime.

[steveyb]

well ive managed to sort 1 problem out. the fuel pump issue is now resolved...turns out it was the fuse that had melted away. replaced it and is working fine again. The ither issue with the electric windows is still there. tonight it was worse than ever i normally have the window down a bit to try and stop the windscreen foggin up and pulled up at my destination. then tried to close the window and the engine almost died. think if id have held the switch any longer then it would have cut out completely. so i kept tryin it with the same result until i turned off the engine and then it worked again. im wondering if its the electric window switch has had it?.....any other suggestions?

[weazgti]

I have just spent ages trying to work out why my car was missing especially with the window switch pressed.
The ignition module on the ecu was sparking on the ecu cage which made the car run rough and sometimes not start with the fuel pump relay chattering like mad. Run the car with the tci unscrewed from the cage (thanks rj by the way) and it run fine until i touched the tci back on the cage. Had a spare one handy so i fitted it and its sweet as a nut now,no electric window misfire.
Wasnt just the window on mine it was anything switched on, i got to the stage where i couldn drive at night cos the headlights slowed the car down 

[rubjonny]

i wonder if some muppet has wired them in wrong, funny one this but try the windows while the car is cranking over on the starter. if they work then its wrong, someone has wired them to a coil live feed. if they did this without using a relay then chances are they've spliced into the ign switch black wire, and its pulling too much voltage while windows are active and starving the coil of power.

the correct way to wire them in is with a relay, the ign live feed is merely a trigger for this relay so they dont pull too much power.  you can get away without using a relay however, but you must try to use a x-over live feed instead (i.e. live with ign on but not when cranking) as draining too much power from this wont effect the engine ignition system.

of course it may just be the base idle, co and timing need to be adjusted, perhaps idle so low the isv cannot compensate for load on the electrics, or perhaps the alternator isnt so great.

[steveyb]

right sounds like ive got a bit of back breaking under-dash wire checking to do then!! that will be my first port of call as it resembles spagetti junction under there. looks like its had an alarm bodged in and ripped out at some point in its life!! wish i could just start with a fresh loom, there's black electrical tape everywhere with spliced soldered wires underneath...nice!!
im pretty sure its not the idle as its 1100rpm when cold then just below a grand when warm, which i think is about normal. The timing should be right as well but i wont rule it out as its hunting a bit on tick-over.