1999 Passat 1.8 20V running rough

[mrbmcg]

My 1999 1.8 20V non-trubo ADR engine passat has been off the road for a couple of years and I'm trying to resurrect it.

The first problem I had was that it refused to idle correctly and would hesitate badly. In addition, a relay under the drivers side would click and the throttle body motor would turn back and forward constantly if you switched the ignition on. I performed a throttle body adaption with vag-com and the idle problem got a lot better, however it still does not idle perfectly and still hesitates badly under load.

When I clear the DTCs using vag com, the following DTCs appear. 17916 and 16685 are not always present, but 16705 and 01120 always appear after clearing.

17916 - Idle control Sys: Upper regulation limit reached
P1508 - 35-00 - -
16705 - Engine speed sensor (G28): Implausible signal
P0321 - 35-19 - - - Intermittent
01120 - Camshaft adjustment 1
04-00 - Mechanical malfunction
16885 - Vehicle speed sensor: Implausible signal
P0501 - 35-00 - -

The car does start and is just about drivable. An additional symptom is that when I accelerate from first to second for example, as soon as I lift off to change gears, the fuel pump relay (I think) cuts out and the car jolts badly. The annoying thing is that once the car is doing a decent amount of revs (>3000rpm) it seems to get a lot better.

Does anyone have any ideas? I'm not sure where to start?

Thanks
Bob

[martin1810]

If the camshaft sensor fails the ecu relies purely on the crank sensor which is not as accurate. Change the cam sensor and see what happens.

[mrbmcg]

Thanks for that martin.

Just another bit of info, the car actually runs exactly the same with the camshaft sensor disconnected. I was astonished to find that it even started, never mind ran.

Do you think this is more evidence for the camshaft sensor being to blame?

[mrbmcg]

Hi All

An update.....where do I start :zx11:

Ok, I left the car for a week then tried to start it. It wouldn't start. Well that's not quite true....It does start, revs up to about 2000 revs then dies again. I'm can definitely hear a relay clicking off (fuel pump?) just as it dies.
If I try to start the car again without turning the ignition completely off, it does not catch, but if I turn the ignition completely off, turn the ignition on again, let the fuel pump prime and then start it, it will catch again, but it dies, just as it did before. :mad:

Another strange thing has happened too. Before this I was able to use vag com to read the engine DTCs, but now I cannot connect to the engine or the instrument cluster and several other control units, but I can connect to the climatronic,radio,abs,airbags and the centre console. :confused:

When I do try to connect to the Engine or the Instrument cluster a hear a very faint beep/click from the instrument cluster, but it does not connect.

Any ideas? I'm totally confused :confused: