Hello folks, would appreciate your thoughts on following.

(Sorry to duplicate thread that was in "Ask a Tech" for few days, but got no response there)

55 plate 1.2 Fabia rough at idle; worse under load in low gears, with lots more rpm per gear, and clutch control required. e.g 1200 rpm to prevent stalling when moving off and manouvering. Drives like a pig. Normal at higher speeds (50mph+).

No fault codes (presuming scan tool was VAG compliant).

Compression test reveals nothing. All ignition coils replaced, but no improvement. Mechanic stuck for ideas.

100k, one owner, fsh except previous 2 yr gap where did 20k with no oil change.

Can compression be checked under load?. Any electrical item other than ignition leads & spark plugs a possible culprit ?

Thanks for reading, and for any guidance you can give. Much appreciated.

Knock or map sensors giving intermittent readings can cause this apparently without showing up codes.

Exhaust valve not seating correctly is not unheard of.  If you can look at the live data and see a misfire counter you may see the misfires getting logged for one cylinder but won't be serious enough for it to illuminate the management light.

 

A compression test won't show much of a difference in compressions, what your mechanic needs to do is perform a leakdown test, which is where you get the cylinder up to top dead centre with the valves closed and fill it with compressed air and then have a look to see where it is escaping from.  If you hear it hissing out of the exhaust pipe, the exhaust valve is the problem.

My bet is valves also.

colzie64

fordfan

hutchysrs50

 

thank you all very much for the quick help.

Good starting point for further investigation.

I have identical problem like Monkey. I did compresion test, change EGR valve, change sensor of temperatur, change a few seal of injection, new candles, new valve N80, cleaning air flap. Mooving off is very terrible and igling is no regular. VAG shows no errors. If I delete adaptation data, do mooving off is better but for short time. This problem takes more than 2 years :-(