ray_hennig
MB Enthusiast
Hello All,
This applies to a W124 with M104 engine.
Have you got hot idling/start/misfire issues?
Have you got Bosch KE Jetronic injection?
Have you been through the ignition system and cleared any problems there?
Have you got an air intake temperature sensor that measures open-circuit (infinity ohms) regardless of air temperature? That's the sensor that screws into the side of the air filter housing, just before the filter element.
I answered "Yes" to all the above so I went online and found a Bosch sensor from a 'discount' parts place for €30. I then went to local MB place and got it for €12!!
Anyway, I got home and left the car idling.
Plugged in the duty-cycle meter and measured, as I thought, 50% +- 2%. Fine.
I then removed old sensor, installed the new one and plugged it in. Duty cycle then shot up to low 90s. Adjusted back to 50% and went for test drive.
ALL SEEMS WELL!
Next test will be leaving the car in the sun for 20 minutes and then restarting. Right, I've done that and ...
Pretty well as new. If I'm to be hyper-critical, there was the slightest misfire on first pulling away but then all was well. I should stress here that I'm still on the original, 19-year-old distributor cap - I cleaned it up and re-installed it after a breakdown with the 2-year-old Bremi replacement, so the next item on the agenda will be an MB cap that I've negotiated down to €200 from local MB - I also have agreed 15% discount in general on parts.
So, the moral of this story is, "Replace that sensor with the new one you've got from MB". You can't afford not to. It may be the cheapest repair on record!
Bonne chance all.
RayH
This applies to a W124 with M104 engine.
Have you got hot idling/start/misfire issues?
Have you got Bosch KE Jetronic injection?
Have you been through the ignition system and cleared any problems there?
Have you got an air intake temperature sensor that measures open-circuit (infinity ohms) regardless of air temperature? That's the sensor that screws into the side of the air filter housing, just before the filter element.
I answered "Yes" to all the above so I went online and found a Bosch sensor from a 'discount' parts place for €30. I then went to local MB place and got it for €12!!
Anyway, I got home and left the car idling.
Plugged in the duty-cycle meter and measured, as I thought, 50% +- 2%. Fine.
I then removed old sensor, installed the new one and plugged it in. Duty cycle then shot up to low 90s. Adjusted back to 50% and went for test drive.
ALL SEEMS WELL!
Next test will be leaving the car in the sun for 20 minutes and then restarting. Right, I've done that and ...
Pretty well as new. If I'm to be hyper-critical, there was the slightest misfire on first pulling away but then all was well. I should stress here that I'm still on the original, 19-year-old distributor cap - I cleaned it up and re-installed it after a breakdown with the 2-year-old Bremi replacement, so the next item on the agenda will be an MB cap that I've negotiated down to €200 from local MB - I also have agreed 15% discount in general on parts.
So, the moral of this story is, "Replace that sensor with the new one you've got from MB". You can't afford not to. It may be the cheapest repair on record!
Bonne chance all.
RayH
