Hi there my 16v mk2 is running rough under load it starts and drives just like usual but when u go more than half throttle it starts playing up. I have replaced: Dizzy Rotor arm Dizzy cap Leads Spark plugs Fuel filter Coil All of these where the guenine parts or the best u can get because i dont like cheap copy parts haha. I also done a compression test and all was very good. Any advice would help massively thanks in advance Paul
Check the cabling to the in tank fuel liftpump and the pump itself. Is the high pressure pump noisy ? Throttle cable OK between pedal and throttle body ?
The pump has only been noisy once in the summer i got stuck in traffic and i think it got a little hot and died but i left it for 10 mins and was fine again The throttle cable is fine a wee bit stiff but ok
Simple check worth doing is look at the earth strap between the engine/box and chassis is it poor or loose? Failing that I'd be looking at the fuel pump it could be struggling under load but ok at low rpm also fuel filter could be rank if your running one. Maybe give the injectors a clean if no joy there. Sent from my iPhone using Tapatalk
it could be a few things i'd check the in tank lift pump when mine went it would bog down when you booted it relatively cheap 20 or so worth just changing it for peace of mind plus if you find out later it's the main pump you've already done it as if you do change the main pump it's advisable change the lift pump at the same time if it's the injectors that feels more like a misfire worth checking the spray patterns
1st thing if u suspect lifter pump is unplug the main pump under the car then turn the key 1 click, you should hear the lifter prime. if not, its dead or wire issue. though even if it makes a noise it could still be dead to check for that pop feed line off and run a hose from it to a bucket then prime again to make sure it actually sprays fuel then have a read in here: http://www.clubgti.com/showthread.php?195423
