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Discussion Starter · #1 ·
Some of you may remember that i said that my 55 wasnt running right, it seems to be a bit worse now! I have changed all the spark plugs today, no change, took it to have a diagnostic check on the computer, came up with missfire on all cylinders except cyl 1? we took it for a drive whilst it was still attached, he said that it seems to be running lean? He said that the MAF was fine, so havent cleaned or changed that. so i am going to change the fuel filter next, i also took it to an exhaust specialist, he thought that the cats were fine, (as i was thinking that it may be back pressure from cats)

my car runs fine under normal conditions, but if you accelerate hard or drive at high speed this is when the power loss occurs?

what you guys think?
any help appreciated, (least cost options!)
 

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2002 ML320
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I would say Spark Plug Wires; this was the fix for me.

My truck was throwing codes for miss fires on all cylinders speratically; I ended up limping home a few times.

My Indy advised me 80% of the time its the wires on these things; he was correct in my case, replaced wires and all is well for over 1 year now. The plugs should last 100k miles easy on these things and from what I know rarely are the cause.

This was the only issue I ever had with my truck, minus the recalls. I just turned 70k miles this morning.

I ended up escaping this one for 450 bucks.
 

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2000 ML55
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How many miles on the 55?
 

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Discussion Starter · #4 ·
61k
I also put some injector cleaner in yesterday to see if that helped a bit, done a few miles with it in now and it hasnt helped......

should i change all the wires then?
 

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My truck had exactly 60k also when I ran into the same issue you describe.

I would replace all spark plug wires; especially if you can get it done in the $400 range.

I was lucky too have a very knowledgable Merc Mech with tons of W163 exp... I think your having the same wire issue that hits many W163's.

Too fully service your engine can get very pricey, it very well could be a Coil Pack but I'm leaning towards the wires, hope you get this resolved soon and update us as too the final fix.

I have $50 on the wires :)
 

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Discussion Starter · #7 ·
played about with it today,
i dont understand why under normal conditions it runs fine? only under higher acceleration does it seem hampered? if i select first and try and accelerate, it is really sluggish and missfires but if i accelerate in 3rd at 2000rpm it is fine????
would the wires not cause a constant problem? the lack of power under higher strain leads me more towards fueling? i have been told that the maf is working fine, he was checking it whilst we were running, but i will clean it anyway, i checked the cats tonight to see if they were glowing and getting too hot, they weren't i also banged the silencer boxes and no sign of it breaking up? so dont think it is exhaust, but the symptoms to me, seem like problem getting rid of the air quick enough? heres another one for you, i managed to get upto a reasonable speed (not saying how fast, but fast enough) when the car really started to missfire and slow down, i pulled over re-started and it was fine? huh????????

HELP!
 

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I'm not kidding when I say exactly what you are describing was my issue. I was able too drive my car for weeks before I got it fixed. My car would miss fire and go into limp mode but only when I would hammer down the peddle and hit say 4k RPM's. I would then pull over, let it sit for a few and restart: everything would be fine until it happened again.

My wires did not cause a constant issue, but I'm sure they would have in due time.

Either way, you never want too just dump it in the shop, get the codes, clear em and drive around until it throws more codes too verify the possible issue.

I still have my dough on the wires. I hope you have a trusted Indy. I miss my Volvo C70 in times like this, what an easy car too DIY service that was.
 

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Discussion Starter · #10 ·
rob you owe me $50! it was maf! this thing must of been clogged for 6 months! never been like it is now! like a rocket! yipee! bloody 10 min job fixed it!
 

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2000 ML430 SOLD, 2007 BMW 328i Coupe, 2014 BMW i3, 2019 Honda Odyssey
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It never ceases to amaze me how a MAF can cause such a wide variety of symptoms and such headaches for people.
 

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Discussion Starter · #12 ·
all i would say guys if anything is wrong check the bloody maf first! i only cleaned mine with a brush! i nearlly got rid of my 55 as i thought is was rubbish! NO CHANCE NOW! plans back on, i will post you guys when i have my body kit on, i havent seen a picture of the kit anywhere other than the ukraine where i am getting it from,
 

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2000 ML430 SOLD, 2007 BMW 328i Coupe, 2014 BMW i3, 2019 Honda Odyssey
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all i would say guys if anything is wrong check the bloody maf first! i only cleaned mine with a brush! i nearlly got rid of my 55 as i thought is was rubbish! NO CHANCE NOW! plans back on, i will post you guys when i have my body kit on, i havent seen a picture of the kit anywhere other than the ukraine where i am getting it from,
Nearly sold a perfectly good E300 diesel in the midst of the high gas prices because of a bad MAF. You'd think the car was possessed when you turned the A/C off or sat at a light. It stumped 3 shops and finally the dealer in Ft. Lauderdale got it right.
 
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