ABF lumpy, VW mechanic stumped!

[Sgt_Lemon]

try running car with it disconnected. you could also check all the wiring to it for breaks.

On this idea you could also do a continuity test in the wiring also. Make sure it hadn't been melted somewhere by the exhaust.

[Simeon]

Soooooo, just to keep this updated for your continued entertainment...

Changed lambda sensor, which sadly didn't resolve the issue. Checked continuity of the wires and all good.

Then I started it again and got the following additional fault;



So, I've pulled the wiring from behind the manifold and although there are no breaks, there's a couple of suspect bits. Going to replace those wires and try again.

[Simeon]

The saga continues!!

So, this weekend we swapped out the loom (the 'vw mechanics' had messed around with the old one quite a lot). This time we used the mk3 coil and did away with the TCI set-up as all the wiring is 25 years old and thought we may have more luck using the newer set-up.

It's up and running, but it intermittently dips idle a little and hunts, then misfires at higher revs Also seems to run quite rich as smells of fuel. No codes being shown on VCDS unfortunately.

Going to stick some fresh fuel in it and see if that helps, then take it for a run and give it some beans to clear the cobwebs. Not holding out too much hope of that fixing it though.

Rev counter is playing silly buggers though, which may point towards a problem: when you turn the ignition on, the rev counter sweeps up to about 5k then back down to zero. Behaves itself when you start the engine. Anyone have any ideas what would be causing this? We have added a spade terminal to the Mk3 coil, then connected this to G1/12.

 

[Simeon]

Pulled the plugs, it's running very rich! Probably get some fresh fuel in it on Wednesday.

Any ideas what causes an ABF to run rich, other than the ECU temp sensor (white one on side of head), which I replaced last year.

[lemski]

Lambda, but you say thats new and working?
Unplug the temp sender and bridge the connections so that the ecu thinks the cars warm.

[Simeon]

Cheers for the reply. Yeah was having a read last night on various forums about ABFs running rich and the recommendation is to try running it with the lambda disconnected, so I think that's my next step. Good idea re the temp sensor, next time I get it warmed up I'll try it.

[lemski]

Doesnt even have to be warm. I did it with a 20vt converted mk2. Bridge the plug and it ran peoperly.
But that was using mk4 plug and wouldnt read. So swapped for mk3 temp sensor. Rewired and sweet as a nut.

[Simeon]

Interesting, I'll give it a go, cheers.

[Simeon]

Shockingly this now has an mot Engine is running ok, still a bit lumpy at idle and rev counter sweeps when you switch ignition on (but not every time), but drives ok, so happy days.

Moral of the story ... lease a brand new car and get on with your life

[Neo Badness]

Moral of the story ... lease a brand new car and get on with your life

Lol'd at that. I have a mk2 ABF that is being a dick having been sat outside in cold but now with similar symptoms. Good info pointers on where to start so cheers