Hello everybody, I've heard it said that these forums are where the most hardened of VW diesel-wizards hang out and so I come to you with some questions. To get it out of the way, I have read and searched quite a bit around here and that's all been very helpful.
I bought a Quantum TD wagon off some kid last month who didn't know a thing about cars yet who thought he could daily-drive a 30 year old VW. It runs and drives and really all I noticed on the test-drive was that it smoked a lot, had no exhaust left, and needed serious attention paid to the brake system. But it started right up, held an idle, everything (except the A/C) worked, and it was inspected so I took her home.
Now here's the thing; he mentioned that the throttle would hang up and said he was told the cable needed to be replaced. Upon taking a closer look, I discovered that it's not that the throttle hangs up, it's that once the engine gets farther up into the revs (around where it starts making meaningful boost) it starts to run away. If you hold the throttle lever at about halfway it'll start to run away slowly at first and then take off towards redline. Here's the thing though, if you let go it will hang for a second or two and then wind back down to idle no problem. In my searching of runaway problems I wasn't able to find anything like that mentioned in other threads.
So at first I thought I'd check to see if the turbo was the culprit; but, with the boost hose unhooked from the intake it still does it. It'll do it with the oil filler cap and vc breather both off, too.
Anyway, I'm not really looking for a "OMG WHAT DO I DO" type of thing here, moreso I just want to bounce ideas of y'all. So what are your thoughts? I'm inclined to think that well, maybe it's not oil after all? Maybe the pump or injectors are dropping too much fuel in there and it starts to run away but then when you cut the fuel it burns off the excess and then winds back down? We just pulled a running 1.6l (well it was before the headgasket blew, but fuel-wise it was good) out of a Rabbit that'll be getting a TDI soon and I thought I might swap the injectors over and see what happens and then swap the pump over (it had a turbo-pump on it) over and see if that makes a difference.
If it is oil, where's it coming from? Down the stem seals? I haven't done a compression test but if you pull the cold-start advance lever and glow the plugs it fires right up at the first touch of the key when cold and has no problem starting when hot, either.