misfire when hot only!

deano1976 · Post by **deano1976** » Tue May 20, 2008 11:30 am

Here we go again! I have a 1994 480es 2.0i automatic that will misfire when it hot only. She has had new ignition module, leads, cap, arm and plugs - thought I would start with the basics!!!

Still misfiring when hot. Haven't read fault codes yet as I abandoned it at a mates house 150 miles away!!!

Please help anyone?

rpruen · Post by **rpruen** » Sat May 31, 2008 8:46 pm

This could be the crank position sensor, the hall effect sensor output drops when warm, and can lead to a misfire. Autos are particularly prone to this, as the sensor 'reads' a thin steel plate not a flywheel.

Try swapping the sensor and see if it helps.

Richard

deano1976 · Post by **deano1976** » Sat May 31, 2008 9:01 pm

Many thanks for that! I will give it a try. I was getting worried noone had any idea!!!!

Will let you know. Collecting car monday so will take spare crank sensor with me. Well, one of my GT anyway! I know that one works!!!!

gingherheed · Post by **gingherheed** » Wed Aug 13, 2008 2:44 pm

This happened to me. Took it to VOLVOTECH in Nomansland and the mechanic pulled open a connector, cleaned it, and put it back. No further problems.

This also happened in my old 1.8 440. Though it turned out to be air mass sensor that time.