Still having trouble solving this problem 94 940 Turbo-Wagon with 111,000 miles B230FT not Regina System Car starts well and runs great once warmed up but on Cold Start it has a Rough Idle, Motor shakes quite a bit. Gets worse when one puts foot on brake when getting ready to shift into reverse to head out for the daily grind. So far I have had Replaced: Crank Sensor (via Volvo recall) Plugs (using copper) Plug Wires including Coil wire (Bougicord) Distributor Cap (Bosh) Rotor Button (Bosh) Fuel Filter (generic) Air Filter (generic) Switched to Synthetic Oil with new Oil Filter Cleaned Throttle Body (new TB gasket) Checked for Vacuum leaks (found one off TB) Motor Vac Cleaned IAC (no difference after cleaning)(two terminal IAC, check resistance and got 7.8 ohms) Exchanged IAC with second hand unit (no difference after swap, seeks fast idle (approx 1100rpm) and then drops to low idle (approx 750rpm) very quickly. (maybe too quickly?, approx one second) (also two terminal IAC, check resistance and got 8.6 ohms) Now there is a blurb in the Volvo FAQ's stating that some cars were fitted with the wrong EPROM in the ECU that controls the IAC and this blurb describes my problem to a Tee. But I found the EPROM Sticker on the ECU and checked with Volvo, it is the correct EPROM in my car. Rats, I was actually hoping it was the wrong EPROM. What I don't know is if the car came with this EPROM or if the car had been re-chipped at some point. If it was re-chipped and one was sloppy about static charge then the EPROM could be damaged. But I found no additional sticker on the ECU stating that the car was re-chipped. So I am thinking that car came with proper EPROM but perhaps EPROM is just plain faulty? Wouldn't there be other symptoms? I don't have another ECU for trial at the moment. May prove difficult to find. Can anybody shed some light? Would the temperature sensor (ECT) under the intake manifold be a possible culprit? Thanks
