W163 - Back at Indie garage

[mercman1969]

in the continuing saga my W163 is back again at the indies in Nottingham

Had a very very long chat with them prior to handing over the keys as had done a few weeks worth of fault diagnosing

Asked if they could do a dynamic diagnosis using the STAR and even offered to attend and drive it 'my way' and let the techie concentrate on the read outs

Well - just spoken to them and they confirm a HUGE mis fire....trouble is they say it is not throwing up any fault codes??

I await a call back from them - fault has only really been apparant since they changed the plugs - they had it in and changed the camshaft sensor that didnt fix the problem....they are now checking leads, plugs, coils ect

Lets see how good they are and if they can fix it

anybody with any thoughts / comments on this are most welcome

 

[wobbly]

Huge missfire, would probably be a coil pack at fault.

One of the only problems I had with my w163, was when it had a miss fire, I was told by the AA it was bad fuel, and after draining the tank, and no difference,it was found to be the coil pack.

 

[IanA2]

My 163 recently had a very slight misfire which was cured with new leads. Given that the problem materialised after the plug change, have they tried another set of plugs?

 

[maddog]

not unknown for a new plug to be faulty

 

[Number_Cruncher]

>>they are now checking leads, plugs, coils ect

Having re-read the original thread, I think that your garage are now definitely looking in the right area.

One cheap test is to look at the engine running in the dark (you may need to take some trim covers off) - if the HT is leaking to earth, you'll see the spark. If you do this, be careful to keep your hands out of the engine - although you won't be able to see the fan and the pulleys, they're still running!

The other thing to do is to get the HT from each plug lead in turn displayed on the oscilloscope while the engine is running badly - if the trace isn't obviously bad, you'll need to check (or ask the garage to check) the peak firingvoltage, and the burn times.

 

[mercman1969]

Well,

It 'appears' that it could be either the leads or the coils
According to the data cylinders 1 & 4 are 'out of limits'

The problem occured AFTER they changed the plugs which is what prompted me to 'guide' them that way

Is it a false economy to only change 2 lots of coils / leads....is it a case of once 1 has packed in, the rest probably arnt far behind??

 

[gazz]

Ask them how they pulled the leads off the plugs...

 

[mercman1969]

To update people on this

I changed the coils on cylinders 1 & 4 today - couldnt source original leads so not done them as yet

Car feels much much better - am sure a new set of leads will also add to the better drive