ABF lumpy, VW mechanic stumped!

[tshirt2k]

It's more to do with a voltage regulator inside the relay failing, that doesn't give the correct voltage to the ecu. IIRC.

[Simeon]

In case anyone is reading this with a similar problem, I eventually took a trailer down to Bristol to pick it up so I could have a look.

A cursory check of the static timing revealed it was 4 teeth out on the cam .... removing the crank pulley revealed it had stripped the keyway on the pulley. This is why I hate it when garages just plug things into laptops and expect all the answers, they could have figured this out in an hour if they had actually checked the timing..!

Anyway, I have replaced the pulley, dowel pinned it onto the crank, replaced the fuel filter and tidied up the wiring (which the garage didn't leave in a particularly good state) replaced the ISV and although it runs, it doesn't run well

I have compression tested it and cylinders 1,2 & 3 are about 12 bar, cylinder 4 is about 10psi down on the other three. Doesn't suggest bent valves to me, so that's a start.

Once it is up to temp the idle will slowly drop to about 500rpm, before the car blips itself back to about 1500rpm before dropping to 900rpm and then starting the whole process again a short time later.

Another issue is that the pulleys on the crank end seem to have a relatively significant amount of wobble in them, it's definitely either the mounting face of the crank nose to the crank pulley or a twisted crank has been suggested?

I'm getting my hands on a code reader in the next week or so, so will plug it in to see if any of the sensors are throwing a fault code.

[weazgti]

Mine idled same before Christmas.
Brake pipe clamp on fuel pressure regulator vac hose made it run nicely when it was doing this

[Simeon]

Thanks for the thought, vac pipes are all new and tight.

Plugged it in, got two fault codes;

Air inlet temp sensor - not surprising as it wasn't connected.
Throttle Position Sensor.

Cleared the codes, plugged in the air inlet temp sensor, started it up, checked for codes again and none came back.

Anyone got any bright ideas about how I can check whether the crank nose is flat without removing the crank?

Anyone got any thoughts on the idle issues?

I'm grasping at straws now, engine might get pulled and replaced in a couple of weeks..

[tshirt2k]

Bit of a bump. Did you sort crank nose? Had a similar issue with an ABF. Used a hammer to peen of the high spots then draw filed the nose with a small file.

[Simeon]

Nope, spent a while trying to sort the crank nose, but the pulley is all over the place. Decided to pull the engine and start again, gonna do it in a few weeks when I have the time. Bit of a pain really.

[Simeon]

Just to update, purely for your entertainment...

We fitted a new engine over a weekend a couple of weeks back, bolted all together and it started and drive fine

However, we had a tapping from the top end, so I decided to swap the tappets over from the old engine, not a big job (he thinks..)

Whip out the cams, swap the tappets over, refit and find that 4 of the cam cap studs will not torque up. Great.

Remove those to find they have previously been helicoiled/bodged, who knows. New helicoil kit bought, studs repaired, bolted back together and think .. finally sorted!

Nope. Now it barely runs, back fires etc etc. Immediately thought I'd cocked up the static timing (been there, got the t-shirt) so double checked it and all seems fine

Bugger

The time of messing with old cars is slowly drawing to a close methinks, next year I'll have my professional qualification in hand and I can go join those old buggers on the mk7 board 

[Sgt_Lemon]

That's a whole bunch of bad luck there bud. Don't go to the dark side just yet, burn that bad luck to the ground or break it and start a fresh.

[roberto]

did you compress all the old oil out of the tappets before fitting? if not then try that. I use an m8 bolt and vice for it. bet that will sort it

[roberto]

infact do a compression test first to see what like.