Follow-up to my 156 emissions fail....

The cat. has been replaced and the emissions are actually fine now.

However, it's still failing the MOT because, when holding at 'fast idle'
the ECU is dropping the revs from 2700 to 2200 rpm on a constant
throttle - it does this for a couple of seconds then recovers back to
2700rpm.

However, when the revs. drop to 2200rpm, it causes a 'spike' on the
emissions result leading to a fail.

The ECU fault light isn't illuminated - it also has a clean air filter
and a new set of plugs.

It's going on a diagnostics test (OBD-II compliant, not main dealer) on
Monday in order to (hopefully) diagnose the issue.

We've already dismissed the AFM, but could it be the TPS or the idle
control valve?

Cheers,

--
SteveH 'You're not a real petrolhead unless you've owned an Alfa Romeo'
www.italiancar.co.uk - Honda VFR800 - Hongdou GY200 - Alfa 75 TSpark
Alfa 156 TSpark - B6 Passat 2.0TDI SE - COSOC KOTL
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