Vag-com blocks for Passat? Surging problem!

[blitza]

Hi all,

I'm having an issue with my '98 Passat B5 1.8T tiptronic (AEB). It's stock, as far as I know.

1. I have Vag-Com, but I'm not sure what measurement blocks I should be using. Is there a link that shows me exactly which ones I should log?

2. My problem is that the car pulses or surges as I'm coasting. It's noticeable, even to passengers, by around 500rpm. It does this for about 15-20 seconds and then settles down for a while (some time later it will start doing it again). Just before it starts I think I can feel a slight shudder in the car. The only error I find in the log is a Brake Light Switch ("implausible signal").

Any ideas?

Cori

[sci_fianime]

Not sure of the measuring blocks...

but it sound like a vacuum leak issue - do you have a boost gauge?

[blitza]

I don't have a boost gauge, but I think VAG-COM can log boost. But I can't find where that might be?

It's now become a little more pronounced, and more rough.

I am pretty sure the mechanic has cleaned the throttle body and the injectors. But I'm not sure.

[sci_fianime]

do a google on ross tech, if I recall correctly, they had a manual on how to use the Vag-com software including the measuring blocks...

[Transporter]

I don't have a boost gauge, but I think VAG-COM can log boost. But I can't find where that might be?

It's now become a little more pronounced, and more rough.

I am pretty sure the mechanic has cleaned the throttle body and the injectors. But I'm not sure.

Engine controler, measuring block 10 and 11

[h100vw]

I don't think you an see boost on the AEB motor. I'd look at the gearbox ECU as well.

Best thing to do is start the engine and go through the measuring blocks one at a time until you get the one you want.

I'd look at the MAF and see what that's up to. Could be jumping around or dropping off intermittently.

Gavin

[Transporter]

When you brake the injectors deliver 0 fuel. If the brake switch would be faulty intermittently that could explain surging. Check the brake switch and replace if in doubts to see if it corrects the fault.