ML320 W163 Misfire P0302

[spedge]

Hi All

I have a 2000 ML320 W163 110,000 miles, that is showing a only P0302 No.2 Cylinder Misfire.

The misfires only occur under very heavy acceleration at over 4500-5000rpm.

keeping it under this rpm it is fine, turn ignition off and on and fault clears.

I have replaced the Plugs x 2, Leads x 2 & Coil pack (tried 3 different ones) and also tried a new MAF.

The car originally had several misfires across multiple cyclinders but it was overdue a good service (all plugs now changed) and only this code comes up.

What are the next steps to check, could it be an injector?

Your help and support is greatfully received and help me out many times before.

Thanks in advance
Simon

 

[momomo]

Are the coil packs and MAF either genuine or Bosch?

 

[spedge]

Hi, the MAF was not Genuine but an Ebay special, the coil packs are genuine but secondhand. I have tried them in different positions and placed a known good item in pos. 2.

Would an inferior MAF only cause a misfire on one cyclinder ( yes I suppose if it has an already weak mixture).

si

 

[momomo]

eBay special MAF's are known not be to any better than the faulty MAF's that they replace. Some have had luck but in most cases they will cause the same issues.

I would not rule the MAF out until tried with a new or a known working one, either genuine or bosch parts. Does sound like a fault that a bad MAF would cause.

Also get it to someone who has STAR if you can, they can easily pin point what is causing the problem if they know what they are doing.

 

[spedge]

Many thnaks, I dont know of anybody in the North East that has a Star machine, I will need to find out who is closest to Newcastle Upon Tyne / Northumberland.

 

[momomo]

Here you go:

http://www.mbclub.co.uk/forums/mercedes-specialists-across-uk/68228-staithes-garage-newcastle.html

http://www.mbclub.co.uk/forums/merc...-mechanic-north-east.html?highlight=newcastle

http://www.mbclub.co.uk/forums/merc...rers-northld-cumbria.html?highlight=newcastle

http://www.mbclub.co.uk/forums/merc...s-uk/41588-servicing-newcastle-upon-tyne.html