Hi Brickboarders,

This story might be of interest for you. Had trouble with an intermittent "shake" of the engine (B230 FK, Volvo 940 with LPT engine '96)and short drop in the rpm, while waiting at e.g. traffic lights in Drive. Checked sparkplugs and rotorcap, cleaned IAC valve and throttle body, checked in tank pump and injectors and performed all the usual tricks (thanks for all your replies!)The problem seemed worse while the engine was under load while idling (in Drive while foot on the brake)
When I explained my frustrations to a friend he told me that last year his wife's car (Mitsubishi Galant V6) had a similar problem and went back and forth to the dealer. They even took out the ECU but couldn't fix it. Eventually (after hundreds of dollars in labour costs!) they went to another small and local garage where they instantly replaced the spark plug leads and the whole problem disappeared. I phoned this garage and had an interesting conversation with the owner who told me that so often myterious idling or performance problems stem from defect spark plug leads!! He said that "heat soak" has quite an impact on the leads and told me to change out leads every 75.000 km's. I ordered a fresh set of "Bougi Cord" leads and the problem has now disappeared!! Lesson to be learned. I was digging to deep! Start at the basics.

Baz
Christchurch, New Zealand