1988 300ce engine wont start help!
 

engine start and instantly shut off even i rev it high it wont stay on no more than 2 seconds and when i looked to speedometer the RPM didnt move just stay on 0. got checked my mechanic yesterday he said fuel distributor, and after i told him the RPM didnt move he said 90% ignition control module is the problem. so my question is which one is most likely the problem? thanks for any advice

It sounds like its on the ignition side of things, you can rule out the cap, leads, and plugs, otherwise it wouldnt start at all. I dont think it's the fuel metering head as these normaly give signs of hard starting long before they fail. As the rev counter dosent move when you start it, I would have a look at the flywheel sensor behind the head, by the oil filter. These can give problems with the sensor "going blind" or the wires breaking down. It has a long lead that plugs in to the bottom of the ignition control unit, its worth a look before replacing the ignition control unit. ;)

thanks for you reply. its hard to start the engine when its cold but the mechanic said its because the adjuster on the air flow meter broke so he cant adjust it anymore. i dont know if this helps. so you think it towards more to the ignition module?

I would check the sensor I mentioned first, but it dose sound like its towards the ignition module. As a side note adjusting the screw on the "air flow meter" or in your cars case, the "air sensing plate" will have no affect on the cold starting.

Thank you! i will check that sensor.

oh i forgot, how do i know if the sensor going bad? im waayyy too green about this kinda thing

First take it out and clean it, you will see a 10mm bolt holding it in the top of the block behind the cylinder head. Undo the bolt and gently pry the sensor out with a screwdriver, try not to pull on the wire to much. With the sensor out, try and start the car. It shouldnt fire at all as this sensor tells the ecu about engine rpm and related ignition timing. Now clean any grease from it, put the sensor back in its hole and try to start the engine, if it now fires (or even better runs ok) the sensor is working. Hope this helps.

kodoq39, sounds like a bad crank position sensor to me.

When the ignition control module went on our daughter's 1991 300CE the engine would not start at all. From your description your engine starts, but won't stay running. Ignition control modules are very expensive (around $2,000) so you don't want to arbitrarily replace it. Hopefully it's something far more simple and less expensive like the CPS.

The best way to ensure longevity of the ignition control module is to regularly replace the distributor cap, distributor rotor and spark plugs ... say every 30,000 miles ... plus check the ignition wires for signs that they need replacement. Weak ignition components stress the ignition control module causing it to fail.

That would be the sensor I was refering to, but on these cars it reads the flywheel insted of the crank pulley so I refer to it as a flywheel sensor.

to remove the crank position sensor it helps a lot to remove the oil filter first. air filter housing is removed also. access to the sensor is difficult even with the filter removed. the sensor may also be stuck pretty good in the hole. a post above mentions a "10mm bolt" fastening the cps, it should a 5mm socket ('allen') head screw that uses also a 5mm hex key. a long set of extensions and universal or two make it easier to get at it.

This sensor also provides the speed signal to the OVP which distributes it the to fuel pump relay and of course the tachometer.
If the speed signal is not available the fuel pump relay cuts out in a few seconds, shutting the engine down.
Always best on an M103 with starting and running problems to look at the most likely problem which is the OVP.

Any luck with your starting problem?

i had this problem recently at it was the cps

other checks
 

it would be a good to check the fuel pump relay for operation as well. Key on to start position the pump should activate for a few seconds , and should be audible
regards