I am trying to resolve a few problems on my son's recently purchased '86 240 (B230F / LH 2.2). When we got the car, the DPO had hooked up the constant idle circuit with one hose blanked off. Now that I have corrected the hose routing, but when the air control valve is plugged in the engine revs to maybe 3K rpm. When the throttle is blipped the idle drops briefly to normal, and then revs back up. I have unplugged the valve so that he can drive the car, but need to figure this out. I can hear the throttle switch closing when the throttle is closed.

I am also trying to troubleshoot hesitation coming off idle and during acceleration. The car has a nice smooth idle and is smooth at speed but almost dies moving off idle though it revs freely when parked. It's worst accelerating from a stop, and only a very gentle throttle will work or it will die. At speed, anything but very slow acceleration will cause loss of power & hesitation. The thermostat in the airbox had failed when we got the car and it had been breathing hot air from around the exhaust manifold for who knows how long and so I suspected the AMM, but the car does driver better with the AMM plugged in than not. Actually the off idle performance is about the same plugged in or out, but plugged in it will accelerate much quicker to speed though with surge and hesitation. Do AMMs fail completely, or could this one be bad but not completely failed? How do I test for this?

I still need to get a Bentley manual; the Haynes seems to be better for earlier cars and not much good for 86 and later. I know we need to replace the wiring harness but am trying to sort these issues out so that son can takes driving test on Monday.

I have been reading this forum since buying the car last March and it has been a great help! Many thanks to all.


Cliff