Yet another W124 M119 that does not want to start

[dalek]

Friend of mine has a 95 E420 that, as the title states, is not really eager to come to life. By that I mean you crank engine and it does not come to life. So, we replaced the engine harness, changed distributor and cap, and put a rebuilt EAS. Now if you crank it and hold the gas pedal 3/4 down or more, it will start. But then to reach and idle of, say, 1000 rpm, you have to gently back the pedal off until reaching that. But, you will need to keep engine running by using the gas pedal

Anything we could have overlooked?

[emerydc8]

Several years ago a member posted how to reset the ECU. Maybe this will help. Also, I presume you have changed the fuel filter, pressure regulator and checked the fuel pressure at the rail?

You can reset adaptation back to Mean Base Line by re-setting/re-activating the ECU memory. After you have cleared all existing codes [Single flash verification ], you then hold button for 6-8 secs. after the single flash. [wait 2 secs after single flash].. Turn off key for 2 secs, On for 10 and then start.

This is NOT a code clear, it is ECU memory reset. That gets your ECU back to Normal. From there the unit will adapt to the new parts and sensors, but rather then coming back from high adaptation extremes, it will come up/down, +/- as required from a Normal Base value.

The ECU can/will readapt from the old memory by itself with drive cycles [ relearn process] , but if the trims were way out , you can still get codes coming back while the process takes place..so, it is easier to just clear/reset the memory after you have changed parts and have cleared the diagnostic codes ..you are then assured of starting with an ECU that has a Mean Base Line setting value..[ ie..a Normal setting]..which should be closer to proper adaptations with the new remedy parts.
Just a short-cut........

[vexed]

Any codes? May want to remove and clean the MAF with some CRC MAF cleaner. Check the fuel pressure regulator by disconnecting the vaccum hose at idle, if there's fuel present replace it