SL/R230: rough idle 2005 SL500
Thread Starter
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Joined: Dec 2010
Posts: 103
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
rough idle 2005 SL500
I took my car in for the 30000 mile B service. had the fuel injectors cleaned, coolant flush, oil change. Also had the engine and trans mounts replaced under warranty (Thanks Bruce). when I got the car back it has a sporadic rough idle that rocks the car and I can really feel it in the seat. Took it back to dealer after a couple weeks to see if it was bad gas or possibly dirt from injector cleaner. they ran the test and said it was possibly a plug wire and recommend wires and plugs while they are in there. $1500! wow. That was a lot to "see" if that was the problem. they had it on some machine that showed the plugs not getting the proper volts. There are no codes in my system for a misfire. I ordered plug wires on line from autohaus. they are karlyn sti and plugs for 300. I was researching and karlyn is an oem manufacturer? Am I making a mistake by using these? mercedes wires are $20-$50 each and I need 16 of them. Also any tips on changing the plugs? other than letting the engine be cold!
Thread Starter
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Joined: Dec 2010
Posts: 103
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
i got the karlyn bremi wires, when i took the originals off they were Bosch. bremi had 1kohms on them but the factory had 2ohms on them. going to return them ahd get bosch
Junior Member
Joined: Feb 2010
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From: Washington DC Metro
2003 SL500, 2005 ML500 SE, 2005 CLK500 Cabriolet Avantgarde
Really interested in how this turns out for you. Just started experiencing the same symptoms too after an oil change. Car feels like a tractor 
.
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Thread Starter
Member
Joined: Dec 2010
Posts: 103
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
ordered 2 coil packs and swapped them out 2 at a time to see if I could find one that was bad. still feel the car idle in the seat. with the hood open you can see it shaking. Glad I did not pay the dealer 1500 to find out that the plugs and wires were not the issue.
Any suggestions on next part to replace? I will check the seal around the engine cover and MAF. After some research here it look like an egr might be the issue.
Any suggestions on next part to replace? I will check the seal around the engine cover and MAF. After some research here it look like an egr might be the issue.
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Thread Starter
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Joined: Dec 2010
Posts: 103
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
The dealer just replaced them. That's when it began to shake. You can see the engine shaking at idle with the hood up. I did not notice or look prior to the issue. It shakes like a highly modified v8 would. I have a mustang and it idles smoother
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Joined: Dec 2010
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
Took my car to an indy here in Tempe Az. Star Services. They had it for almost a week doing every test they could on the ignition. everything was perfect. moved to the air fuel. replaced the mass air but still same problem. finaly called today and said they figured it out, the harmonic balancer has slipped. replaced it and rough idle gone. they are going to see about warranty covering that and other issues then I will get the car back. some have said they have the same issue. here is another thing to check. will post when I get it back to let you know if that was the solution
Thread Starter
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Joined: Dec 2010
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
Vibration damper on the end of the crank shaft. It's the big thick pulley at the bottom center of your engine. Offsets the imbalance of your internal rotating parts. Like a weight on your wheels.
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Joined: Dec 2010
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
yes it runs a lot smoother. they also replaced an idler pulley, egr, valve cover gakets. Engine does not shake at idle!! Thankfully I had the extended warranty wich saved me a ton. If you have the rough idle you can now check this part. You might be able to see that it is going bad. the rubber could be sticking out of the pulley.
Newbie
Joined: Feb 2013
Posts: 3
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SL500
I have the same issue, engine shake ramdom when is in idle in park or neutal. If engine in over 900 RPM no shaking. Local Benz dealer were unable to point it out. I have new cables, spark plugs, mass air flow sensor, fuel pump. No missed fire or check engine or computer codes. Damper looks fine. I just don't what else to check o replace. Thanks for any feedback
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Joined: Feb 2013
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Daytime: Slow and easy with 2006 SL500 & 2003 S430 . Night time: Hard and Fast with my wife
Eclipse.. what model year is your SL? Groves73 has '05 and I have an '06 and I am starting to worry if this issue would carry over to my model year. (even though my car has only about 5K miles on it)
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
only use Chevron 91. The other day my check engine light came on. took it back to the shop and it was something to do with egr which was just replaced. they found a vacuum leak in the egr system tubes. got it back and the idle is good but tht happened last time I got it back. will report back in a week if it does or does not return. I hope this is the last time I have to get work done on this car for a while!! i am about to give up on it if more problems arise. just love the car when it run right.
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Joined: Dec 2010
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
and the rough idle is back a week later. ran perfect for a week. only happens at idle. With all the work that has been done above it runs perfect off idle. real smooth and strong when accelerating. i am going to switch to Shell gas but dont think that is the issue. Has to be a vacuum issue somewhere. is there any vacuum in the trunk with the soft close? That was another part they replaced in the first service. It is such a sexy car and drives so nice I dont want to get rid of it. just the idle sucks now. will take it to one more mechanic. not sure if the motor mounts that were just installed are good. Engine lifts pretty far under load.
Thread Starter
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Joined: Dec 2010
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
check engine light came on again. back in the shop. last codes were egr and mass air flow. I am having them check that and doing a smoke test. will post again when i get an update.
Newbie
Joined: Feb 2013
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SL500
My rough idle is finally gone, I discovered that after I unplug (cable & vacuum hose) from the EGR valve and didn't make the engine shake wors. Got a new one from napa $159.00 and about an hour of work to replace the valve. Also replaced 4 inches of vacuum hose that connect from EGR valve to the intake manifold. I hope this solution will save time, money and frustration to anyone having the same issue. I expend about $900 before I got it right and many visits to the shop.
Thread Starter
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Joined: Dec 2010
Posts: 103
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2007 CL550, 2005 SL500, 1984 380SL 1985 Mustang GT
So glad to hear you found your problem. I am hoping one day I can say the same. I did have the egr replaced. Check engine came on and it was a vacuum on the egr. Took it back again with engine light on, it was vacuum on a vacuum pump? Each time I get it back it runs like a top...... For about 5 days. Egr made top end rpms nice and strong. I am going to try another shop to find vacuum leaks. Car has been in the shop 5 times since end of December it's march now.
