Can anyone tell me why my 190E (2.5 petrol) exhibits these symptoms :

Engine warm, at idle:

Blip the throttle - the engine bucks a little, has a stumble.

Disconnect the EHA/control pressure actuator, engine warm, at idle:

Blip the throttle - engine responds more cleanly, no stumble or bucking


This makes no sense. The EHA is supposed to provide enrichment?? Yet it's better without it???

Go out on the road though, you'll find the characteristics aren't duplicated. Instead, without EHA it is pretty laggy to respond to the gas pedal. With the EHA back on it is "okay" only. Bunch of rubbish this KE.

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190E's:
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black 2nd owner
http://www.maylane.demon.co.uk/190esmall.jpghttp://www.maylane.demon.co.uk/190esmall2.jpg