Hi all and Merry Christmas!

On Dec 21, our MY92 240 developed overnight the worst 'flat spot' on starting for the want of a better description. I tried to book her in to a dealer but all the ones in our vicinity were booked solid until after Christmas. So here I am up to my elbows in grease and DTC's for Christmas. Thanks Santa :(

The DTC retrieved from the EZ-116K diagnostic unit 2-1-4 which, according to Bentley, indicates 'Speed sender signal missing or sender faulty'.

Strangely then, the speed sender passed the function check by flashing 1-4-1.

Since, according to a mate, difficult starting is meant to be an indication of this unit failing and we had that symptom for a while, I replaced it. We need to crank the engine for a while and every now and then it would 'sneeze'; like a backfire.

Since I thought the engine was starving for fuel, I then had the injectors tested and ultrasonically cleaned, replaced the distributor cap and rotor and, while starting may marginally be better, getting moving from stationary is nigh on impossible. It's as if the car is gasping for something; air or fuel.

Timing is spot on at about 13 deg BTDC.

No further DTC has been captured.

This car has been serviced regularly by a dealer and has about 112k km on the clock.

While I have been undertaking this surgery, the emission warning light has lit on the dash. From what I have read, this is a reminder to replace the oxygen sensor at the cat. Is it related to the problem at hand? Australian cars do not have the Lambda-Sond system (I think). There is only one ECU behind the passenger kick panel.

I have bought a fuel filter, just in case, but haven't been able to undo the hollow bolts on the old one. Could it be a clogged filter? The one on the end of the pickup in the tank perhaps?

Diagnosing a 200 used to be easy. Now, with so many sensors and computers, one needs a Cray to get off first base. I can see I shall have to risk the dealer once more.

Any help would be greatly appreciated.

Merry Christmas once again from a hot-but-not-burning-today Sydney, Australia.
Ivan