A140 misfire could use some help please!

[geordie john]

Hi, I have taken a customers car in on Friday with a really bad misfire, really lumpy at idle and wouldn't rev at all. The plugs were changed about 200 miles ago at a dealer. I removed the coil pack and checked them - they all look OK. Thought I could hear tracking noises from the coil pack and tried insulating tape over the rubbers but to no avail. Replaced coil pack with new one at £60. Still rubbish. Connected SP ACR4 diagnostics and had 7 codes - mostly lambda related. Cleared the codes and I am now left with 2, both the same. The code is 072501 TN speed signal short to B+. Does anyone have any ideas? Thanks in anticipation.

 

[chez]

i had same kind of problem

have a look at these hope they help chez http://www.aclassinfo.co.uk/mypage.38.htm http://www.mbclub.co.uk/forums/showthread.php?t=49397

 

[jaymanek]

think you have the usual a class ECU issue...
I sent to these guys who were unable to repair but tried hard..
http://www.peacockandpurvey.co.uk/mercedes_a_class_ecu_and_air_f.html

I then had to buy a new ECU costing me almost £1400 including coding at the dealer...