1995 W125 220E, misfiring... leading to non start. Loom repaired... still non-start!

[Basil7]

Hi, I bought a 1995 W124 220E, to replace a car that had been pranged by the misses. Anyway it had done some 500 miles over the last couple of years. When I bought it and drove it home 50 miles, about halfway back it started misfiring with a noticeable loss of power under load, but made it home. Restarting the following day it ran okay until it warmed then misfire. The car ultimately broke down the following day, only driven out of a need to get to work. Looking at the engine I noticed the wires attached to the intake air temp sensor wires had lost their sleeving. Also on closer inspection the lead nr the plug for injector 1 was also exposed wire. After a little clicking online about loom issues I removed and resleeved with heatshrink all the wires apart from the coax to crank sensor and cam sensor, that seemed according to my research to be less of a problem.... so all the conventional wires. There was evidence of prior work including to coil pack wires, bits of the loom wrapped in insulating tape and sealant and other general bodgery. This done (including coil pack wires),

With the car reassembled.... it turns over lumperly and spits and farts but won't start. I put a strobe light on each lead getting a flash off each lead, spark tester on the end of leads (instead of spark plug) showed a spark not spectacular but okay I guess... red-blue spark a little wavy. Noid lights on injector wires... all 4 having a pulse. I have tried a secondhand set of plugs that are old but believed to be okay. I took the crank sensor out and did an ohms test 700 ohms (at room temp) 900 ohms (when heated with heat gun).... touching the sensor end with steel it read open circuit. I have ordered a flash code reader, to check for codes, I don't have a engine check light showing on dash.... not even when ignition live is activated on key in the position prior to cranking. I'm assuming I should have the light on the dash cluster and it has probably had the bulb removed

I'm starting to lose the plot a little so any suggestions would be very welcome, as the car apart from this is in relatively good shape.

 

[BoristheBounce]

Hi and welcome.

You say the car has only done 500 miles over the last couple of years; any idea how long it had been stood around before that, it may be something as silly as the fuel has gone off or the fuel filter is minging or even the pump is faulty????

 

[Basil7]

Hi and welcome.

You say the car has only done 500 miles over the last couple of years; any idea how long it had been stood around before that, it may be something as silly as the fuel has gone off or the fuel filter is minging or even the pump is faulty????

In my ownership it had about a tank of new fuel (still has around 1/2 a tank).

I only found out after I had paid that the guy I bought it off had only bought a couple of months previously.... I'm assuming in that time he found some issues that looked expensive and off loaded it onto me (without telling me). The owner before that was an elderly chap who got a motability car and stopped using the Merc.... so it sat around a little and low annual mileage before that. I guess I should check the fuel pressure on the fuel rail.... and change the filter.

That said I had done 200+ miles before it packed up completely.

 

[Basil7]

Hi and welcome.

You say the car has only done 500 miles over the last couple of years; any idea how long it had been stood around before that, it may be something as silly as the fuel has gone off or the fuel filter is minging or even the pump is faulty????

Oh I should also say.... I did a compression check, good on all cylinders and plugs 2,3, and 4 also looked damp suggesting fuel present but possible issue with injector 1.

 

[Basil7]

Hi and welcome.

You say the car has only done 500 miles over the last couple of years; any idea how long it had been stood around before that, it may be something as silly as the fuel has gone off or the fuel filter is minging or even the pump is faulty????

I can hear the fuel pump working both prior to cranking when key at ignition live and briefly just after cranking suggesting it is active when it should be. If it is getting injected or even reaching the engine in sufficient volume/pressure is yet to be established.

 

[Smiley]

There's no EML on the 124 from memory. Regrettably sometimes the loom problems can fry the ECU.