Mystery GTI (99' 1.8T), and lots of problems!

[benbenjamin]

Hi there,

So, I bought myself a cheap GTI with a view to doing it up. As far as I can tell it's largely standard. High mileage (150k) but seemed half decent for the price (£550, I wasn't expecting much!, but it needed a clutch and had an abs problem). Then naturally when I got it home I found loads wrong with it.

Managed to diagnose the driver's side wheel speed sensor (using vag-com, no other fault codes were recorded. Drove it for a day, still no other fault codes recorded), hopefully replacing that will stop the ABS from freaking out. And there's a list of about 30 other little things that need doing. But I'm having a bit of trouble figuring out a few things and wanted to see if anyone had any ideas.

First up is the really rough idle. It's less rough when it's cold, and gets worse as it gets warmer, cutting out at traffic lights from time to time. Engine power seems fine, just doesn't seem to want to idle.
When I got the car the temp gauge didn't work. So I replaced the coolant temp sensor, which sorted that out. But it didn't solve the rough idle. Is that likely to be new MAF/clean the throttle body? (I've given the maf a good clean with electrical switch spray, seems very clean now, but didn't improve anything). It makes a slightly rough sound when it fires up for half a second, but I don't know if that's the ABS unit freaking out, or engine related (hard to pinpoint). I've taken a few videos but it's hard to hear:

http://www.youtube.com/watch?v=fUEayMMbm1Q


The next mystery is the radiator fan. It doesn't work at-all. I thought replacing the coolant temp sensor might solve it along with the temp gauge, but no joy. Then I discovered some mysterious things.. Firstly this:



I have no idea what should be in the yellow fuse slot (it's a none AC 1999 1.8T), but I'm pretty sure there should be a lead running through the red arrow powering the radiator fan?. It's not dusty like the yellow slot, and look like it's been removed recently.. Hmm. Very suspicious!. Any pointers here would be great . While looking at manuals and guides and things I've managed to find on the internet I've noticed that all of the radiators for GTI's that I've see have 2 fans. One large, on he driver's side, and then one smaller fan on he passenger's side (UK car). Mine's only got one, idk if that's normal?.




Lots and lots of other issues, which I'll list and post the solutions to as I find solve them, but these are the most important at the mo. Any advice would be much appreciated!.

[mcgee9t2]

red radiator fan fuse. 40A link fuse, need one myself, PITA to get, cant find anywhere but vw to get one from, and they don't stock them.

the other link fuse missing is 50A for coolant glow plugs

as for rough idle could be numerous things, sounds to me like either a minor boost leak, temp sender/stat could be frigged, but think youv changed stat, could also be maf as you've said.

[brewey]

Agu engine I'm guessing so could be ignition amplifier, which has been suggested recently to a few others with similar problems. However, it could be a multitude of things. Coil packs maybe but I would think it'd always be rough if it were a coil pack.

[houston]

I'd say do a throttle body clean, check the plugs, fuel filter, air filter. Ignition amp or coil pack wouldn't affect idle much but would really be noticeable when the cars up the revs sp you can rule them out.

1 fan on radiator is normal if you don't have air con

[Perryd84]

I'd say do a throttle body clean, check the plugs, fuel filter, air filter.

+1 to this! The rough idle sounds similar to how mine went I cleaned the throttle body and it sorted itself out.

[sharki786]

I had simular pronlem with my agu, when i reved it, it would hunt like a cnut under its idle point. Gave it a full service (oil, oil filter & sparkies) and took the throttle of and it was full of gunk. Cleaned it out it all back together changed the dv with the breather hose for a silicone under the inlet and its all good now. So cleaning the throttle and replace with a new seal and see how it goes from there bud.

[Wazzzer]

If you have no AC then you don't have any use for the extra fan...