Hi, I `ve just bought a golf 1.6 driver which the engine was running well and nice and smooth from cold and also when hot. I recently renewed the brake pipe which runs behind the carb - before when i drove it into the garage the idle was nice and low, after i `d finished the work, started up and now the idle is way too high. I thought i may have caught or knocked something behind the carb when threading the brake pipe through, but i cant` see anything obvious and all vac pipes appear to on and in place. I have noticed though that the throttle cam which the throttle cable sits in is sticking open about 5-10mm short of the stop. I can push it back with a screwdriver and the idle goes back to normal, but then it springs back. It feels like i`m pushing it back against a spring or possibly a vaccum. Is there anything obvious i can check? The carbs are a bit new to me! I've had a couple of the digifant gtis but never a carb driver. Cheers, MIke Here`s a pic of the cam i`m talking about -
The throttle cable being pretty slack is absolutely normal, because other bits of the carb are holding the primary throttle open when the engine is switched off (in a good position for when it's switched on again). The high idle is consistent with a vacuum hose disconnected from a thing called the 3-point unit. Borrowing a picture from rubjonny's legendary how-to thread on these carbs, the ones you need to check are the pink ones at the bottom of the image. The 3-point unit is the thing bottom right; it governs the idle speed at start-up and fully-warmed up, but if the vacuum signal isn't there at its lower port, it won't retract from the start-up position of a fairly open throttle. When warm this position gives an embarrassingly high idle of about 3k rpm.
Hi, Thanks for the reply - i should`ve replied earlier, but i did find the problem and it was indeed the vacuum hose had come off the 3 point unit you mention. This did lead to an embarassingly high idle ! Running well now though ! Cheers, Mike
Well done Mike. Complicated-looking, but mostly made up of simple, separate bits and pieces. It's just when they're all there together it looks like an explosion in a vac-pipe factory...
