Hard starting 1991 240

My 1991 240 has recently become difficult to start. I have replaced the spark plugs, leads, distributor cap, coil, fuel filter, and air mass meter. My experienced vovlo mechanic plugged the car into the diagnostic unit and no fault was indicated. The teperature of the engine does not influence the hard starting. Once started the car drives perfectly. I travel 60kms per day at at 140km/hr. Sometimes the car will start easily but usually it takes a few attempts. It is getting a good spark. The Haynes manual seems to suggest the ECU unit maybe a potential cause. Does anyone know if this is likely? and can a 2nd hand unit be fitted?
The car has travelled 190 000 kms and has a full service history. It has automatic transmission. Any assistance, advice would be greatly appreciated.

Ben
Ontario, Canada

[Mike_Brace]

Does the voltage to the coil increase on cranking? If not needs wire from starter to coil replacing - this gives a hiogher voltage on cranking to help starting.
Mike

[Peter D]

When you say you have decent spark, is that with the fault condition or without. The common cause of this is the TDC sensor behind the head. Volvo issued a replacement sensor due to reduced output on cranking. Once it starts ir runs fine becuase the fly wheel is spinning faster than cranking and a larger signal. Easy test, next time it won't start get a tow or a good 3 amn bump start and if she fires up there is your problem. ( this sensor does not report a fault when cranking fact ).If not then you need to see the LT waveform at the coil on a scope as this could be a coil problem with a shorted turn internally but I doubt it. Regards Peter

[abulloch]

Ben -

You've probably done this already, but you may find some useful tips in a similar topic which I started earlier this month 'Problem starting when cold or damp' (topic #2955 on the board).

It was the idle valve that solved the problem for me, but there were some very useful hints/recommendations about other remedies to consider.

Good luck!

Anthony

Thanks Mike and Peter for your response.....

Since talking to you both the coil was replaced with that from a 740 turbo. This seemed to solve the problem temporarily but now it is just as hard to start as ever.

Mike: the voltage when checked does increase on cranking.

Peter: I have a decent spark with and without the fault condition.

Any other suggestions now it has a new coil? The car has been running without a stove pipe but I putting a new one today. Would this influence the starting? Do you think it's worth replacing the TDC sensor?

My Haynes manual says hard starting can be a result of the ECU. Would this be likely as these are very expensive to replace?

I attached a picture of the car in the summer...and the dreaded Canadian winter. I don't think it has anything to do with the cold as it was difficult to start even in mild weather.


Thanks again,
Ben

I replaced the TDC sensor and cleaned the throttle housing..... now starts first crank even in -20 degrees celcius. Thanks for the help.