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1997 SL500
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Discussion Starter #1
Hi.I just bought a 97 SL500 (gorgeous)with very low miles. I am having some issues and could use some assistance please. It has been driven very little in the last year. The car is running rough. In particular at stop signs it skips a bit and surges a little. The idle seems to be all wrong too. I have been told by a couple of people that claim to be familiar with the 97 SL500 that this is common to the year/model. Is this true? Someone at the dealer mentioned there is a fix for this (I have a call in but have not received a response yet). It runs perfect on the highway and at high speeds. It is also not starting well; although, it is turning over. Any comments on this or general comments on the car. This is my first Mercedes. Helpful hints...thanks! Lynn
 

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BenzWorld Elite Member
2004 SL55, 2006 Range Rover Supercharged, 2013 Infiniti M37
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312 Posts
Lynn,

Had the similar problem with my 98. When I inspected it I noticed a rough idle - asked the sales rep. to address prior to delivery. Upon delivery it had same issue, sales rep. called service manager who explained that this was inherent in this model, year, engine, etc.
I wasn't satisfied with explaination but there was little I could do as my ride there had left & the dealer was approx. 1hr. from home.
About a month later service engine light came on & I brought to local dealer to repair. I also asked them to verify / correct cause of bad idle.
They changed the spark plugs - there was a noticible improvement in the idle.
I purchased the car in 03 with 31K miles.

I hope this helps, good luck.

Hi.I just bought a 97 SL500 (gorgeous)with very low miles. I am having some issues and could use some assistance please. It has been driven very little in the last year. The car is running rough. In particular at stop signs it skips a bit and surges a little. The idle seems to be all wrong too. I have been told by a couple of people that claim to be familiar with the 97 SL500 that this is common to the year/model. Is this true? Someone at the dealer mentioned there is a fix for this (I have a call in but have not received a response yet). It runs perfect on the highway and at high speeds. It is also not starting well; although, it is turning over. Any comments on this or general comments on the car. This is my first Mercedes. Helpful hints...thanks! Lynn[/QUOTE]
 

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clk350
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71 Posts
I'll probably get a bit slammed for this, but the 5.0 does have a bit of an idle lope even when well tuned.

As the previous responder notes, changing his plugs offered improvement.

In my own experience with the 5.0,a 1995 you need to remember that all of the parts of the distributors are precision machined and any oxidation or slight wear causes havoc. Usually, if it is a distributor problem, the car will not only idle a bit rough, it will run smooth until about 4500 RPM and start to feel like the anchor is out.

Ain't cheap to do plugs, wires, distributor(s) and rotor(s), but I've found it solves a host of sins.
 

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1990 500SL
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146 Posts
on my 1990 what should i be idle'ing at when car is at full operating temp?
 

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SL60 ///AMG
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110 Posts
90-500SL - 4/12/2005 3:35 PM
on my 1990 what should i be idle'ing at when car is at full operating temp?
650 +100 -50 rpm
 

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SL60 ///AMG
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110 Posts
RE: look @ UR users manual

Carlo$ - 4/12/2005 4:04 PM
I looked in the service manual for R129 for year 1990 for M119. Don´t you trust me? [:D]
 

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1997 SL500
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4 Posts
Discussion Starter #10
I have been reading the replies as they post. I didn't realize when I bought this car that I was getting a new hobby! I am really impressed that I have this many helpful responses in this short time frame. Thank you to everyone! I checked out all the reference links and everyones websites AND fabulous cars. I will keep checking back to this post and I am going to relay this information when I take it to the mechanic tomorrow. Lynn
 

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2000 SL500
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106 Posts
The 95 engine is different then the 96-98 engine. The 97 does not have a distributor and rotor, and the wires are not spark plug wires but wires to the coils over the spark plug. By chance do you know if someone put platunium plugs in that 97 engine. I added platnium plugs to my old 97 and I found out that the idle was irratic and would surge sometimes. Once i removed the platnium plugs and put the oem coppers back in the problem was solved.
 

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Hi There,

It could be the idle valve, it can sometimes stick especially if the car has been sitting for some time.

It is situated on top of the engine in the middle of the 'V' and is a cylinder about 3" long with a two teminal connector at one end and two rubber hoses at the other. If you disconnect it at the hose end and give it a good clean with degreaser or something similar it should help.

Always better to start with the cheap stuff!

Good luck

Webby
 

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Sorry Carlos,

I don't have a digital camera, but if you remove the engine covers and air filters you will see what I'm talking about. Did mine a few days ago and it seems to make a bit of a difference.....well it was that or hammering the car up the autoroute at 200KMH [:D]

Webby
 

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1997 SL500
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Discussion Starter #15
Hey Guys. I get my car back Monday. I printed all of the posts from this topic and brought them to my mechanic! He said to tell you all that, "the car is running as smooth as a baby's ass." He loved that comment! Here is what I have learned: Yes the car has the coils that attach directly to the sparkplugs, no they were not platinum. Yes - a bad spark plug....replaced ALL 8 (uhhhhgggg)thanks for the good advice. Also bad MAF (air) sensor and problem with connection on fuel presssure regulator (YIKES- Good thing that is fixed). I can guarantee I won't be parking this poor, poor little car in a garage for months. It seems like it is a lot better idea to DRIVE the car rather than let it sit..Right?! Hopefully I can add a PHOTO to my profile next week! Cheers, Lynn
 

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'97 40th Ann. Edition SL500
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25 Posts
These messages are old, but herewith some (perhaps) new info for consideration...AND a question:

Idle spec given above is correct. Right outta the book! However, know that it is Factory Set and can NOT be adjusted by dealer (so I was told). Here in deep South, hot, HOT idle can cause serious low oil pres., even with 5W-40 EURO Formula Pennzoil Full Syn. Maybe I'll (gulp) go to Mobil 1 15W-50 Spring-Fall. NOW, about Spark Plugs! Owners Manual for '97 SL500 says (#1) Bosch F9DC0, apparently NO RESISTOR. Current Bosch application for this engine comes up F8DC+ (BOS#7927), and WITH resistor!!! I have called Bosch and will have further conversation tomorrow. I DID get a BOS#6726, which I need to pursue. Any advice on "BEST" Bosch plug for this engine???
 
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