pebattrick
New member
Hi everyone. I need someone with some in-depth knowledge of the motronic DME system.
The cat has been getting harder to start when warm for a few months now. It now refuses to start at all when warm and hot. It starts immediately when cold, temperatures from 10degC (today) to -2degC (a couple of weeks ago). The car drives very well but will not restart until it has cooled down again (typically about 1/2 hr.)
I have replaced the ignition system - coil, dist cap and rotor, spark leads, plugs.
Also the DME relay.
The Cylinder head sensor has been checked out , at the DME, and is within spec, hot and cold.
Similarly the flywheel sensors, using the method described by "Specialised ECU repair", are both good, although the rpm sensor reads higher volts than they suggest.
Voltage supplied to the fuel pump correctly but I haven't put a meter on the fuel pressure yet. However there is good pressure in the manifold when the bleed nut is loosened.
The idle position actuator is working and the idle contact and the full load contacts are working. However when sitting with the ignition on, but not running there is a slight vibration from the body (clearly being driven by the DME) and the gubbins inside twitch regularly
Not sure about the Air flow meter but since the car goes well until I turn it off, I assume it must be ok.
The question is - Where next?
The cat has been getting harder to start when warm for a few months now. It now refuses to start at all when warm and hot. It starts immediately when cold, temperatures from 10degC (today) to -2degC (a couple of weeks ago). The car drives very well but will not restart until it has cooled down again (typically about 1/2 hr.)
I have replaced the ignition system - coil, dist cap and rotor, spark leads, plugs.
Also the DME relay.
The Cylinder head sensor has been checked out , at the DME, and is within spec, hot and cold.
Similarly the flywheel sensors, using the method described by "Specialised ECU repair", are both good, although the rpm sensor reads higher volts than they suggest.
Voltage supplied to the fuel pump correctly but I haven't put a meter on the fuel pressure yet. However there is good pressure in the manifold when the bleed nut is loosened.
The idle position actuator is working and the idle contact and the full load contacts are working. However when sitting with the ignition on, but not running there is a slight vibration from the body (clearly being driven by the DME) and the gubbins inside twitch regularly
Not sure about the Air flow meter but since the car goes well until I turn it off, I assume it must be ok.
The question is - Where next?
