B5 S4...Throttle cut out while driving?

[Richard van der Hoff]

Hi Craig,

I don't have much to offer here, but I see nobody else has weighed in, 
so I'll say what I can.

The symptoms you describe are very much consistent with the ECU going 
into limp-home mode. As you observed it shuts down to idle until you 
restart the engine.

As to what causes it to go into limp-home mode, could be almost 
anything: both sensors failing on the gas/throttle body, big air leak, 
that sort of thing. When it happened to me on my B5 S4 it was the latter 
- I'd recently replaced the throttle body, and one of the hoses was loose.

You really do need a vag-com; it would be invaluable in dealing with 
this as it would point you straight at the problem. Without it you're 
basically reduced to checking all of about 500 things on the car are 
working right - you'll spend more time and money doing so than you would 
have spent on the vag-com. If you don't want to splash out on one (and I 
really can recommend one), you're probably best off taking it to a 
garage - you might even persuade one to just plug in their diagnostics 
for a nominal fee.

HTH!

Rich



Craig Porter wrote:
> Driving along on the highway, not pushing the car at all, all of a sudden I
> start to slow down.  I push the gas pedal and get nothing.  Push in the
> clutch and the rpms return to idle....push the gas to the floor.....no
> difference.  I pull over to the breakdown lane, shut off the ignition, lift
> the hood, look for anything visibly wrong with the connections to the
> throttle body and find nothing wrong.  Back in the car, start it up,
> everything is back to normal??  Drove home and didn't have the problem
> again.  This morning, same thing happened after I was leaving from DD on my
> normal coffee run.  Gas pedal seemed to just lose connection(I know its
> drive by wire)This time I slowed down with the clutch in, I shut the key
> off, turned it on, and let the clutch out.  Everything went back to normal.
> 
> Does anyone know what gremlin I may be dealing with??  I searched online
> threads, but I haven't come across this issue.  I don't have a vag-com
> either, which from what I have read would probably help me troubleshoot
> this.
> 
> 
> Thanks!
> Craig
> 
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