SL/R230: Misfires when cold
Thread Starter
Newbie
Joined: Feb 2024
Posts: 6
Likes: 0
2007 SL600
Misfires when cold
I have a 2007 SL600. When starting in the cold (say under 50F) the engine runs extremely rough and I sometimes get a CEL. Scan reveals cylinder x misfire. Trying to drive it - even a little just to move it - is painful (limp mode, terrible sounding).
If I leave the car idling, the engine eventually warms up and then - almost all of a sudden - starts to run completely smoothly. From that point on it's golden; no misfire, lag, or loss of power.
Any suggestions/advice on what to look at first ? MAF, any particular vacuum line, some temp sensor ?
Advice appreciated !
If I leave the car idling, the engine eventually warms up and then - almost all of a sudden - starts to run completely smoothly. From that point on it's golden; no misfire, lag, or loss of power.
Any suggestions/advice on what to look at first ? MAF, any particular vacuum line, some temp sensor ?
Advice appreciated !
Last edited by colobart; Feb 21, 2024 at 07:49 PM.
Thread Starter
Newbie
Joined: Feb 2024
Posts: 6
Likes: 0
2007 SL600
Would they only exhibit an issue when cold ? Once warm, everything's perfect.
I don't get any DTCs from OBD - except for the cylinder misfires. What would show up in a scan if the coil pack was going bad ? (Besides a misfire )
I don't get any DTCs from OBD - except for the cylinder misfires. What would show up in a scan if the coil pack was going bad ? (Besides a misfire )
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
What scanner do you have? You need an MB specific scanner, a generic scanner won't do.
Scan with Foxwell or Launch CReader or similar and post up the codes for comment.
Scan with Foxwell or Launch CReader or similar and post up the codes for comment.
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
I don't have a V12 R230. Yet.
So I follow the discussions on the subject - this is the world expert on the V12 coil packs: https://www.v12icpack.com/
So I follow the discussions on the subject - this is the world expert on the V12 coil packs: https://www.v12icpack.com/
Trending Topics
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
What is the issue with the Foxwell?
It's got the full MB package, but is very slow; I think they all take the same time to scan though.
If you get the Launch, please do report back, I'm interested in seeing a review of it.
It's got the full MB package, but is very slow; I think they all take the same time to scan though.
If you get the Launch, please do report back, I'm interested in seeing a review of it.
MB World Stories
The Best of Mercedes & AMG
8 Oddball Mercedes Ideas That Actually Made it to Production
Verdad Gallardo
Dubai Tuner Gives the Mercedes G-Class An Entirely New Look
Verdad Gallardo
Six Gift Ideas Your AMG Loving Dad or Grad Will Cherish
7 Craziest Things AMG Gas Ever Built
Verdad Gallardo
New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know
Verdad Gallardo
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Thread Starter
Newbie
Joined: Feb 2024
Posts: 6
Likes: 0
2007 SL600
Interface like a 12-year old wrote it. Wouldn't connect to two laptops. Wouldn't save results from a scan. Didn't even ID the cylinder misfire. Picked them up with another scan tool. I could go on.... but you get the point. I am an Electrical Engineer: I have somewhat higher standards for these types of devices; they need to be easy to use and highly complete and accurate. This device isn't either.
I ordered this one: "LAUNCH X431 Elite 2.0 Pro Bidirectional OBD2 Scanner Fit for Mercedes-Benz MB Sprinter Maybach, 2024 Full System Diagnostic Scan Tool, All Reset Service,ECU Coding,Key programming,"
I'll give it a run through and let you know how it goes.
There is something that's causing non-ideal fuel-air mixture when cold. Then all of a sudden it corrects. What component corrects so dramatically ?
I'd love for a scanner to help point in the right direction. Other than that I have to start diagnosing/testing/swapping any sensor that is in that decision making chain (i.e. IATs, MAFs, vacuum hoses, etc....).
I ordered this one: "LAUNCH X431 Elite 2.0 Pro Bidirectional OBD2 Scanner Fit for Mercedes-Benz MB Sprinter Maybach, 2024 Full System Diagnostic Scan Tool, All Reset Service,ECU Coding,Key programming,"
I'll give it a run through and let you know how it goes.
There is something that's causing non-ideal fuel-air mixture when cold. Then all of a sudden it corrects. What component corrects so dramatically ?
I'd love for a scanner to help point in the right direction. Other than that I have to start diagnosing/testing/swapping any sensor that is in that decision making chain (i.e. IATs, MAFs, vacuum hoses, etc....).
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
Not a semiconductor, they don't usually fail like that. Definitely get the full scan and codes and see where you are. Still likely to be the coil packs, why not contact the fella at V12icpack with your symptoms and ask him for any insight? He's a wizard. He's done youTube vids where he x-rays the coil windings. etc
Look forward to your report on the Launch. I agree the Foxwell has a very 1990s look and feel about it...
Look forward to your report on the Launch. I agree the Foxwell has a very 1990s look and feel about it...
Banned
Joined: May 2023
Posts: 209
Likes: 3
just looking
I have a 2007 SL600. When starting in the cold (say under 50F) the engine runs extremely rough and I sometimes get a CEL. Scan reveals cylinder x misfire. Trying to drive it - even a little just to move it - is painful (limp mode, terrible sounding).
If I leave the car idling, the engine eventually warms up and then 신용카드 현금화- almost all of a sudden - starts to run completely smoothly. From that point on it's golden; no misfire, lag, or loss of power.
Any suggestions/advice on what to look at first ? MAF, any particular vacuum line, some temp sensor ?
Advice appreciated !
If I leave the car idling, the engine eventually warms up and then 신용카드 현금화- almost all of a sudden - starts to run completely smoothly. From that point on it's golden; no misfire, lag, or loss of power.
Any suggestions/advice on what to look at first ? MAF, any particular vacuum line, some temp sensor ?
Advice appreciated !
Super Member
Joined: Sep 2019
Posts: 624
Likes: 213
From: My house
SL55AMG, GL450, SLK, S550, Maserati Coupe
The V12s it's important to have good spark plugs so I'll ask how many miles on yours. If near or over 40,000 miles I would replace those with new NGK Platinum Iridium. This may or may not resolve your issue but new plugs will help to keep your coils lasting longer before failing and needing rebuild. I agree that any V12 owner should read Clark's entire website.
MBWorld Fanatic!
Joined: Aug 2020
Posts: 1,340
Likes: 366
From: Gretna, NE
'03 SL55 Black, '03 SL500's Aegean, Mars Red, Tazanite, Alabaster, '11 S550 Flint Gray
It sounds more like a fuel issue to me. On cold starts, the ECU will be open loop, it does not use O2 feedback to correct fuel trim. If you have a temp sensor error, low fuel pressure, or some other issue the open loop fuel mapping can be inadequate and there is no correction until it warms up and goes into closed loop mode.
