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Discussion Starter #1
Just a little info to pass on. My 98 ML320 had a rough idle problem (especially in drive sitting still) and would shut off at a red light or stop sign on occasions. Replaced the MAF, plugs and wires, fuel pump and filter, air filter and cleaned the EGR tube to no avail. My local mechanic told me to check and clean the butterfly valve on the intake. I took the intake tube off and checked it out and sure enough, it had a ring of what looked like hard carbon build-up around it keeping the valve from functioning properly. Needless to say I cleaned it off using MAF cleaner and it runs like a champ! No hesitation, sputtering or rough idle anymore. Hope this helps anyone having the same problems!
 

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Astani. I will but mine is very minor at the min. weather is closing in here. Much more chance of something snapping. I will only do it if i can pinpoint problem, otherwise i will leave it until spring. Main problem is the poor mpg. I was getting 20mp uk gallons now 17.5 to 17. Carbon build up may be an issue, as that pipe has never been off for 6 years that i have owned it.
 

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I would have done this long time ago but look at the space on the ML430. I cannot imagine how you get behind there and do some useful work. Any suggestion would be great.
 

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Astani. I will but mine is very minor at the min. weather is closing in here. Much more chance of something snapping. I will only do it if i can pinpoint problem, otherwise i will leave it until spring. Main problem is the poor mpg. I was getting 20mp uk gallons now 17.5 to 17. Carbon build up may be an issue, as that pipe has never been off for 6 years that i have owned it.
Thank you, I am not in the hurry too. I have a rough idle at the red light stop now and then, but no major problem.
 

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Discussion Starter #8
I have 5"-6" back there when you remove the intake tube but its still a little tight, but worth the effort. I sprayed the cleaner inside and held the valve open with a long extension (so it couldn't fall inside the motor) and used my hand and a small flathead screwdriver to remove the build-up. 1500 grit sandpaper probably would work to clean it all .
 
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