3.0 M103 124 Backfiring!!!!!!!!!!!!

[belly20034]

Well here we go again.
she starts, she run's perfectly, she's get's up to temp, then she's cut's out! after she die's and I try turning her over she make's a nasty popping that I think is coming from the air inlet, then she backfire's. So ive got to leave her to cool right back down to nothing before she will start again. any idea's?

 

[panason1c]

Just a couple of ideas that might be valid (or not)

Possibly an intermittent problem with the crankshaft sensor causing it to cut out when hot, the subsequent cranking when trying to restart would cause a build up of unburnt gases in the exhaust which would cause the backfire when ignited.
Also, check out the inlet manifold gasket isnt leaking.

 

[grober]

Does sound like an ignition problem rather than fuel. Sounds like something's cutting out with engine heat or simply an ignition component overheating-- Coil -- EZL unit

 

[television]

Dizzy cap and rotor arm on a 103 can do this with condensation

 

[panason1c]

Would be good to be informed what the solution eventually turns out to be.

 

[belly20034]

fixed!, i think

Does sound like an ignition problem rather than fuel. Sounds like something's cutting out with engine heat or simply an ignition component overheating-- Coil -- EZL unit

Thanks everyone, Grober you did it again my friend, i went along to my local mercedes breaker and took an ELZ unit and a Coil out of 1991 260e.
He charged me a tenner for the both, Which i was more than happy with.
Changed both of them over and its seems to have solved the problem, i run the car outside the house for 2 hours and drove it round the block a few times, its running sweet, the real test will come tonight when i drive it to my pal's house, 50 miles round trip. Thanks Again Guys

 

[grober]

If that has cured the problem great. These EZL UNITS are getting like gold dust now. If its working OK I would put a thin coating of heatsink compound e.g. http://www.maplin.co.uk/module.aspx?ModuleNo=33695&doy=8m3 between the unit and the inner wing its mounted on ( make sure this has a nice clean surface. The reason they go is because the original heatsink compound dries out allowing the unit to run hot and eventually burn out.

 

[belly20034]

Omg

If that has cured the problem great. These EZL UNITS are getting like gold dust now. If its working OK I would put a thin coating of heatsink compound e.g. http://www.maplin.co.uk/module.aspx?ModuleNo=33695&doy=8m3 between the unit and the inner wing its mounted on ( make sure this has a nice clean surface. The reason they go is because the original heatsink compound dries out allowing the unit to run hot and eventually burn out.

I was wondering what the white paste was all about, ill sort that in the morning. thank you very much, i would have never of thought to deal with that, The ELZ i got was the only one in his yard and he only had that because the car had just come in, infact im gonna start hoarding ELZ's, OVP relay's and all that good stuff, just off the top of your head grober, is there anything else like that you can think of i need to start hoarding? coz lets face it my car is 1986 and things wear out don't they.

 

[grober]

If your car has the JETRONIC K system which I assume from its age,and you have access to that donor car at those prices I would try to get a hold of the warmup regulator, the auxiliary air device, cold start valve, OVP and fuel pump relays and thermo time switch. The ABS control unit/ecu could be useful also. Only worth getting them (on spec ) if they are as cheap as the other parts. I would have said the engine ECU (if it has one?) but if its from a 2.6 it will probably be different from the 3 Litre. Still you might be able to swop it for a suitable one? It really depends on the prices.

 

[belly20034]

Cheers pal, ill grab what i can!