2.0TS Fluctuating idle

Hello all,

Cleaned the throttle body last week, last weekend changed the belts, variator and water pump. Today the car is idling fine but from time to time (let's say every 10-20 secs or so) it suddenly drops and then revs up to correct before it stabilises again.

I replaced the MAF sensor about 18 months ago. Alfadiag doesn't show any fault codes.

This engine still has the habit of cutting out in mid-flight as well, although that seems to have become somewhat rarer (from everyday to every week) since the throttle body cleanout.

Any clues? Can I diagnose more using alfadiag? The lambda sensors seem to work, they do show a nice oscillating graph but do drop to zero volts occasionally and alfadiag responds with a 'short circuit'. However, it all continues fine afterwards.

Thanks in advance.
Berrie

hi,
- check self adaptive parameters TRA, FRA, DTV
on UnidiagKWP2000 software, it's free.
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http://img209.imageshack.us/img209/5...afactorob4.jpg
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http://img337.imageshack.us/img337/9858/lambdaxc6.jpg

Hi Berrie,

Mine was doing this exact thing a few weeks ago. Peak Alfa noticed that my timing was out a bit, someone had put a small 1.6 water pump in it and so the timing belt was loose - got im glad i took it in!).

Running better than ever now!

Someone on this forum did tell me the same thing about 6 months ago but only just got round to checking it out.

Matt!

Thanks guys,

I'll have a play with alfadiag again and also downloaded UniDiagKWP2000_0_3_1_27.

And euroscan, I take it that your screenshot of alfadiag is on a properly functioning engine?

Cheers,
BB

hi,
- not really, lambda sensor is broken.

What is the obvious indication that it is broken? The occasional short circuit to zero?

It doesn't look a million miles away from this one: Lambda Sensor (Zirconia) Waveform

But yours does look a lot like mine ;-)

Cheers,
Berrie