Misfiring stops when restarted.

GeoffTucker

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I have a 1999 W-163 ML-320 which will run fine until suddenly I get a loss of power and it runs roughly. :( When restarted all is well again :).

This happened yesterday when the car was up to temperature and three times on the way home from work tonight, all when the engine was cold. It also happened when the car was cold this morning. Any ideas?

The car is new to me and I don't know the history. My wife has driven the car for a couple of days and had no problems at all. Grrr.
 

Alex Crow

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while we're betting on the cause i'll go with sam/colin's first guess, with a hedged bet on the air mass. i'd bet against the coil pack though.
 

jibcl500

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Colin

did I dream this but if the coil packs start to fail on this engine they can destroy the MAF also?

jib
 

television

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Colin

did I dream this but if the coil packs start to fail on this engine they can destroy the MAF also?

jib

I would say no,,not possible,,it would take the engine ECU out at the same time if it was possible
 
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GeoffTucker

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Thanks for all of your replies so far.

I got the codes read yesterday and there was only one which is PO170 which from looking around is a fuel trim problem possibly caused by MAF sensor, O2 sensor or a vacuum leak.

Anybody got anything to add?
 

japimport

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i dont have the same car as yours,but i had the same problem,i ended up changing the fuel pump,fuel filter,plugs,and put some stp fuel injection cleaner in the tank and im happy to say it hasnt happened since,it happened me a couple of times a day my car is a c200
 

Miffy

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try disconnecting the MAF to see if its the same or worse. if its the same as it was, then try replacing that next, very easy DIY job, 5 mins
 

television

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As Miffy above,,unplug it and see how it goes,,ignore any poor idle that may hapen
 

sistaffs

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Had exactly the same problem with my CLK.
Bought a new MAF off Ebay for £35 and fitted it in 10 minutes.
Totally different car now. Brilliant!
 

television

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The MAF can and does upset the fueling,,this is why it say o2 sensor as well,,but 99% are MAF only replacements
 
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GeoffTucker

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try disconnecting the MAF to see if its the same or worse. if its the same as it was, then try replacing that next, very easy DIY job, 5 mins

It only happens within the first 5 minutes of driving off (engine hot or cold). Is it alright to drive distances with the MAF disconnected?

I am going to have a go at cleaning the MAF over the weekend and see if that helps.
 
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