W126 high idle 650 Sounds right. in mint condition. Heres what I'm experiencing: The car starts and idles fairly smooth, if you accelerate gently, there are no problems. W126 High idle problem. Location: Southern The movement of the control plunger will be limited if the cold control pressure is too high. Jump to Latest 21 - 30 of 30 Posts. I believe the symptom was the idle never came down. Now I'm prepping her to sell and wa When my benz is under load at a stop sign the idle is to slow,about 500. 2 V8 (M116. N. I spent $100 for the Idle Relay & installed it - No Change in behavior 2. I've changed the air filter on my -82 380SE the other day, from the standard paper type to a K&N filter. 02 June 2008, 01:01 AM. Looking for the idle control module under the dash: is it the larger case more the size of a video cassette or the smaller one the size of a small cigarette box? So after a couple months of being spot on my 500 sel has the high idle problem. What would be considered a normal idle and a high idle. I pulled the electrical connection off the Idle Control Valve (idle increased to about 1500) and put a meter on the two pins sticking out A high engine idle can be caused from, a number of issues. For some reason, both of those say they are for a 560 SEL. Hi, Im having problems with my 420se 1990. S. Once it heats up the idle creeps up to 1100 and will not go down. Hi 6. 8mpg confirms this – a leaky cold start injector would not enable even 10mpg. Car will idle in park at 600-700rpm when cold start. so my High engine idle during cold starts is a common phenomenon that occurs when a vehicle's engine is first started in low temperatures. At cold start, engine works fine around 1000 rpm on idle (also works fine from ca 700~800 rpm to up at driving). Friendly solution for those with M110 engine on your S-class If your car suffers cold start annoying high idle issue here is solution to that and it has to do with AAV auxiliary air valve that is too big of Inlet and outlet ID and idea is to decrease ID on both ends of that valve and it will work only on good working valves if your idle is low when cold started that means your valve is TOPIC: 1990 Mercedes Benz W126 V8 560 / 420 HIGH IDLE WHEN WARM. And, can be anything ranging from, a faulty fuse to something a bit more complicated, like a leaking vacuum hose. Key on cold: 12v 2. Mercedes AMG DOHC M117 w126 AMG Widebody SEC 1985 Mercedes 560SE Carat Duchatelet Hi, I'm getting rough idle (on P it's not perfect but good, but in D it has 500RPM and struggles) Is it possible to adjust idle in D? Or is it something with transmission? RPMs drop to about 500-550. Since my ABS light was going on and off intermittently, I decided to replace the OVP. As it warms up to 60 deg C, the idle slowly increases to 1200 RPM. TRUKTOR 265 Replies. W126 S,SE,SEC,SEL,SD,SDL Class Location of Idle Speed Control Module(relay) Jump to Latest I recently had a high idle on my 1985 Euro 500sel. Check the vacuum distribution hoses that The trouble with fitting a manual throtle idle adjustment is that it would be lacking in several areas, cold fast idle, increased idle when a gear is selected or when any other So for a few weeks my w126 has had a high idle issue. Hey guys, I've had this problem for a while now, and I'm about to put it in the shop, but I was wondering if you could help diagnose this issue. Feb 6, 2019 #4 OP . The problem still exsists and now the engine idles a little rough until completely warmed up. MBDoc advised the culprit most likely is the OVP Relay 3. Also, fact that car returns 16. Its for the fuel injections enhanced features. So far, I've tried the following places: Ebay - Hi all Aside from a few other issues, my 300ce is stalling and sufferig from erratic idle, but if possible I was going to try to increase the base idle speed for the time being in the hope that it may stop it cutting out at rather inconvenient times as at the mo I'm having to brake and feather the throttle at the same time every time i approach turn/roundabout/lights etc. I replaced the valve which fixed the high idle, and continued to chase the hot start. 4K views 7 The valve eventually died which brought on a high idle. I have been reading all the w126 high idle problems and resolutions on this forum. TRUKTOR 267 Hello. With that thrown in I think you have a variable vacuum leak. My idle speed went from 650 in park and 850 in neutral to 900/1100. The principles will apply to 4 cylinder, 6 cylinder and V8 engines with Bosch CIS produced from 1976 to 1993. khomer2 1. May drop below 700mA above 2,000m altitude. I haven't seen the ABS light Mercedes W126 420SEL 560SEL Idle Speed Control Unit Module Relay 0045451032 | eBay The relay currently in my car has the part number 0065458532 (W126 Idle Speed Control Module Relay 0065458532 | eBay). I have disconnected the idle speed valve and the idle shoots up to 1700rpm and when I put the connector back on it drops again to 1000rpm, so I presume the valve is working properly. the vacuum is taken off the inlet manifold and if its broken it affects inlet pressure. 3K views 2 replies 3 participants last post by Firewater Oct 5, 2009. 400 when I put it in neutral and then W126 S,SE,SEC,SEL,SD,SDL Class. 1 2. Over Christmas break I was attempting to reset the idle mixture using the screw between the fuel distributor and air metering plate. This increase in RPM helps facilitate optimal engine performance and combustion until the engine reaches its normal operating temperature. 6 DOHC 360bhp by Stratton Ferrari 328 GTS Quattrovalvole 1986 Koenig Widebody His high idle problem will be fixed when he replaces the OVP relay. presuming you sorted out the situation, will you Hi Guys, My 560 starts perfect when its cold, then idles at 600 rpm no problem. 6628 posts · Joined 2012 Add to quote; Only show this user My 89 300 SE with 262k miles has developed a rough idle. Very fast idle on start when cold, eratic idling when warmed and no high-idle for the auto trans. What is the best way to set-up the co without messing the idle speed up? The co is 3. Thanks. If you have a lean miss, then start looking for a vac leak. Posts: 16554. I got my idle back occasionally by cleaning the throttle body. Started by Ryan1980, 02 June 2008, 01:01 AM. 8K views 9 replies UPDATE ON HIGH IDLE Post some photos on the forum the members can advise as to value. transmission. I had a feeling it was a simple fix but I wasn't driving the car. Running Cold: 13 W126 high idle & ASR light. Ötzi 467 Replies. W126 560SEL high/strange idle. 1987 420 SEL, 2000 ML55 AMG, 2001 E430 4Matic, 2007 E550 Joined Aug 22, 2006 My 117. com/MonkeyWrenchMike Regardless of temperature, cold or warm, the car will occasionally seem to miss a beat while idling. A. W126 300SE W202 C240 GR86 GTS FA24. Hi, new member here but been a Mercedes 190e 2. But I think its sending a signal to Idle control relay to raise the ilde thinking the A/C is I fixed 3 different W126 high idle, over the years, by resoldering the circuit boards of the Idle Speed Controller. Currently am still going down the lines for this high idle issue, I’m currently idling at 13-1400 at idle in park. I just replaced the Idle slide valve on my 86' 420SEL. Plug on couple at idle speed adjuster in a manner that voltage can be measured 1. However, on replacing the valve, a new problem arose. 9 forever, initially I would start checking high Hi world. All right, after I discovered my high idle was caused by a faulty IAC, I've searched everywhere to find an affordable price for this part (000 141 16 25). Working on my 91 300SE. I’ve unplugged the TPS and the idle shoots up so, that’s functional. The video will show an example of fixing a fast idle on a 6 cylinder M103 engine with CIS fuel injection. I A small vacuum leak will create a high idle issue , a big one will result in it not wanting to run at all. W126 S,SE,SEC,SEL,SD,SDL Class W126 High Idle problem. I bet I get more info here in the 107 forum though. Jump to Latest 14K views 16 OK, my high idle problem has now got so bad that the car never idles lower than about 1100rpm in park. Also, nowhere did my case did it say "idle speed control" like the one in the pictures. It turned out to be a bad Idle Control Unit which brought the Here is why. This car is a 1989 300SE As far as the high idle <800rpm> issue in drive. The car idles normal in gear and runs good. It revs at 1300 in N or P and 1000 in D. 1990 Mercedes 420 sel 4. Jump to Latest The high idle is intermittent and is 1000rpm when it gets normal it’s 550-650. I can hear a faint ticking noise whilst in idle, this noise was present before this incident as . hey guys, My 280SE has a very high idle, around 1700rpm in park while cold. weathersone Discussion starter. The idle valve is worth cleaning - have a search on here to find where & how. The unit I bought had two fuses in the top while the unit originally installed had only one fuse in the top. The idle should be about 550 rpms warm, 900 cold. I have a 560sec which idles at 17,000rpm when in park and about 9,000rpm when I put it in drive. rumb Discussion starter. Registered User : Join Date: Mar 2003. I did a diagnosis based on The engine was running rough at the scene of the breakdown. Permalink . (750-900rpms in drive/park) Otherwise, the car drives fine. Jim-ML320W164 333 Replies. View Single Post #1 11-04-2011, 02:27 PM jhertzler1103. The car runs rough,but if I put my foot on the gas and bring the idle up to about 600 it runs perfect. Upon selecting D into gear, the engine slowed to 550rpm. Hi guys, I have been working with my high idle problem for over a year now, and are soon giving up. When I start the car cold, it idles at appx 800 RPM. Now I'm prepping her to sell and wa My high idle presented nearly all the time since purchase, sometimes it would idle lower when cold but once the engine reached operating temperature the idle would settle at I have disconnected the idle speed valve and the idle shoots up to 1700rpm and when I put the connector back on it drops again to 1000rpm, so I presume the valve is working Hi all, I'm new to W126 cars as some of you may have read in another thread I recently acquired a 82 500SEC euro import. steve beard Senior Member. w126 high idle User Name: Remember Me? Password: Register: ShopForum Gallery: FAQ: Calendar: Today's Posts: Search LinkBack: Thread Tools: Display Modes #1 11-04-2011, 01:27 PM jhertzler1103. I f you have high rpm with cold engine (how high is now? ) you should also have high rpm with warm engine It idles very rough at first, hesitates when accelerating from a stop, and idles roughly at stop signs and stop lights. When in drive, the car runs perfect at about 600rpm at all times. Ahh yes. NewMBie Discussion starter 611 posts Hi, My car: MB 280 SE (2. Mvisciano Discussion starter. Save Share Reply Quote Like. Go Down Pages 1. Top Contributors this Month View All. , W126, 185 hp), 1983mod, aut. Hi all, My 1991 420SEL is idling high around 1100 but when in gear it is normal. Cabral. 2 v8, w126. This in turn will limit the amount of fuel able to be delivered through the injectors. Any advice would be very much appreciated. we bought the car about 2 years ago before that it never had any MAJOR work or repair done. 2. I cant find any air leaks. They're now up to $1,300, when they were about $600 late last year. The Mercedes-Benz C Class W204, equipped with the M272 engine, is renowned for its performance and reliability. W126 S,SE,SEC,SEL,SD,SDL Class bob15489. Location: Elverson PA. Seems like I've got a similar problem with idling. 5-5. It is a 20 minutes job and anyone who has a high idle should do this before throwing parts like OVP, ICV, and ICU. Jump to Latest 2K views 3 replies 4 participants last post by jdc1244 Dec 30, 2004. When connecting the ICV at cold the car starts better but the idle rises steadily to 1500-1700rpm when warm so is unusable. Pull coupling from idle speed adjuster and measure voltage. W126 S,SE,SEC,SEL,SD,SDL Class Idle Control Valve and ICU functionality to resolve high idle issue Well, my brush with "high idle hell" was not as difficult as I had expected. Without the ICV connected i. Ignition switched on. In Canada we search the Auto Trader for each province the highest values are Alberta & British Columbia most interst is in the 560 SEL Euros and I just Just purchased a 1986 560SL, 92,500 miles, EXACT same idje issues. 107's ,as W126 S,SE,SEC,SEL,SD,SDL Class Rough idle Vs high idle. 2: Auxillary air valve defective. I'm live in Norway. I noticed that the gas pedal was sticking a bit and the car idled normally after I put I had idle problems on a similar aged 560 sec w126. Status: Offline. Once I replaced the spark plugs and tightened the motor mount, it idles much better although as the owner of the car I can still feel something isn’t right , even without giving it gas. Jump to The condition of high idle speed changes that concept. Replacing the W126 420SE 4. When I switch back to Park after putting it in Drive, the revs shoot up and takes about 2 seconds to come down to 1000 again. The result will be a lean ratio and will cause rough idle. -88 560 still high idle problems after "fixing" most of the related components. I started a thread in the w126 forum first because I figured every (v8) w126 probably has one. After intent listening, it appears this is also the case at higher RPM (barely noticeable, but there) up to aboutr 1500RPM W126 300SE Missing beats in Idle/Rough. fixing high idle 380sel. R. Fresh good quality fuel would be a very good idea if it has sat unused. I tried to adjust this with what appears to be the idle adjustment screw near the air intake and The big ecu doesn't affect idle normally. High Idle - What I found. Ötzi 325 Replies. W126 S,SE,SEC,SEL,SD,SDL Class. 6K Replies. Resistance across ICV terminals of ICV 3. I think i pin-pointed it to a faulty Off button on the climate control head. I have done the following to try to fix it: 1. Hope that helps. Go. 1990 Mercedes Benz W126 V8 560 / 420 HIGH IDLE WHEN WARM. Jump to Latest 8. hey guys new to the forums, got a problem with my 420 SEL its a 1986 with 100k Miles. The last 2 days however have seen the high idle each and every time I start it up. 270K miles. Great to have got in touch. Joined May 21, 2022 Messages 2 Location London Car 500SEL. The small black box is your idle control relay, a common fault item. (1400rpm in park; 950rpms in drive) Hence, what adjustment should I make in order to bring the idle down to normal range. The high idle can be the airflow potentiometer. Every time the valve engaged (vacuum controlled by KE Jetronic fuel injected Benz engines feature an adjustable idle air control valve. What Causes High Engine Typically, a high idle means a vacuum leak somewhere. Hi All, I'm trying to diagnose a high idle on my 1985 500SEL and am after some help. 1; 2; First Prev 2 of 2 Go to page. The car starts and runs great. Having an issue where as the car warms up, the revs increase in Park and Neutral. But when engine is warm (to below 80 degr. Messages 268 Points 125 Location Sunshine Coast. I have a problem with my 1987 420SEL regarding a starting issue when the engine is slightly warm, taking two tries for the engine to catch. 12v then Checking regulation of control unit Engine at idle at operating temp. I have replaced the following Rotor arm Distributor cap Spark plugs Ignition leads I have cleaned the idle control valve and when disconnected the idle rises. In your case, lets assume that timing is ok and that you don't have a vacuum leak. Recommended Communities. W124 R/C107 or W126 FSMs I eventually found it "elsewhere" in a W126 FSM Here's a snippet describing the air idle control valve - from this information it does indeed seem to be working much Thanks. Ötzi 312 Replies. Any new updates or detailed steps to success?! W126 S,SE,SEC,SEL,SD,SDL Class R/C107 SL/SLC Class W163 M-Class W124 E,CE,D,TD Class W210 E-Class. Jump to Latest 698 views Saw some posts on high idling and just wanted to offer a first step and simple check I stumbled on when changing my gas pedal when my car started racing after the change. 29 posts · Joined 2018 Add to quote; Only show this user #1 · Mar 2, 2025. 6. W126 S,SE,SEC,SEL,SD,SDL Class R/C107 SL/SLC Class W163 M-Class W124 E,CE,D,TD Class W210 E-Class. Diagnosing High Engine Idle, Should Start With A Visual Inspection. OP. More Hi all, Just purchased a 1983 W126 280SE with the M110 engine. You could have a look inside. Jump to Latest 3. Could this be a high idle problem? To the other members here where does your car idle at? Park? and Drive? What is the correct idle speed for a 560sec. My '87 560SEL has always run a little weird after it sat for about 8 months, but lately it's been doing some strange, strange stuff. g. I know this topic has been done to death but the threads never seem to lead 1987 W126 Cold Start / Idle Problem. IDLE CONTROL UNIT Location? HELP. Posts: 42 w126 high idle Customer: I have a 1990 Mercedes 560 SEL. Soo have to love the. Q. There are several different types of idle control ,thats why i was asking about the part numbers for the unit applicable for the W126 500SEC. When at operating temp, the engine reaches about 1400rpm when warm in Park or Natural. celsius) and sink to around 500 rpm at idle with part vibration (its feel like engine going to stop). Posts: 42 w126 high idle. User actions. the infamous nasty high idle, in my case 1500rpm ! What amazed me was the number of threads here with no resolution. I am posting voltage readings from a perfect running 1984 500 SEC Euro taken from the ICV pins. on it. Monkey Wrench Mike shows you what a dirty, clogged ICV can do to your engine and how to clean it!https://www. Either way you need to figure out what broke first. The car starts fine and when warm idles at 1100 rpm unless in drive. Issue was not bad sensors, electrical short, or stuck Idle Air Control Valve (IACV) as I had suspected. W126 S,SE,SEC,SEL,SD,SDL Class 1987 420SEL Running rough, idle bouncing, HELP When warmed up, it seems to stall after a longer period of time while the idle bounces between 400-1000rpms and runs quite rough, shaking a About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright W126 S,SE,SEC,SEL,SD,SDL Class High idle. 1FastGT. Thread starter steve beard; Start date Nov 20, 2012; Prev. 2K Replies. 9forever Noble. However, it idles a little high now. TAKE NOTE: If your ABS dash light illuminates when Hi Idle occurs, & goes dark when Hi Idle CEASES, the likely culprit is the OVP: it's interconnected to several systems & can react accordingly. Success!! As the engine temperature reached 80°c, the idle dropped slightly to 650rpm. Firstly, inspect the throttle cable and linkage So for a few weeks my w126 has had a high idle issue. Here are some pics. The first step in the diagnosis, is a visual inspection. I have a number of metering plates in my parts box if you I have all the factory manuals and microifische for the W126 but none have any clear indications about such things as vacuum lines and of course the location of such things as the idle control. Replacing the control unit did solve the extremely high idling problem, but the engine is still idling at 1000 rpm's in Park. The K&N lives up to every word reg. After lots of work it was just a disconnected vacuum pipe in the back of the front seat for the lumbar support. 8L, 6-cyl. Have tried all the following: check all fuses and relays check for vacuum If on these engines a bad AFM potentiometer causes idle to be unstable, then you know for sure that either idle speed control via IACV is not properly / not at all working due to a problem within the idle speed control It doesn't idle fast all the time just 60% of time. The economy pegs to the left when the engine is running idle but sometimes moves slightly making me suspect a small vacuum leak. W. I have the infamous high idle problem which When the car was purchased the idle with warm engine was approx 1600. Testing Idle Valve - High Idle Problem. The engine seems to be hunting as the idle will go very slightly up and down. This may be because I have one of the earliest 380 SEC's ever made Mercedes w126 SEL Brabus Mercedes w124 T Brabus Porsche 911 Turbo SE Slantnose 1986 Mercedes 560E - w124 5. The issue is high idle. It happened twice in the last 2 weeks but each time after work and driving home it would be fine again. Print. 86 W126 560SEL 85 W126 380SE Silver 85 W126 380SE Cranberry 79 W123 250 78 W123 280E 75 W114 280 #4 11-14-2005, 10:16 AM Duke2. Hi Guys, I’ve been trolling the forums here and have looked at essentially every thread pertaining to these issues. . 100, peaking up to 1. All the way in the red is no vacuum, and all the way in the W126 S,SE,SEC,SEL,SD,SDL Class A. To lower the idle speed, I removed the Idle control valve and started to clean it. sitting at traffic lights). VOLTAGE IN THE PLUG: Car running high idle, plug disconnected. Jump to Latest 1. I've been working on 617 and 603s for a long time, so I'm kind of green on the gassers. 985 engine in the 450SLC idles quite smoothly at the specified 750 rpm and normal temp (87C), but it shakes and vibrates the body (e. Hi! I am looking for where the idle speed control module is. Here is a video about how to do that. Rough idle, runs decent past idle and higher RPM’s while driving. e the way it has been since I bought it, the car would struggle to start and idle at 450-500rpm from cold. Understanding this process can help you maintain your vehicle better. 6. Is this the module? Where is it under the dash? My 380SEC has these modules and relays in a different place from where the W126 manual states. increased air flow - problem is that it - alas - also have lifted the idle revs from 750ish to 1. (one) is the most common problem to the least occurring problem. I have the same problem as your w126, and my mechanic located the valve and found if faulty. If defective and not opening, idle cannot rise and results in rough idle. 3. Diagnosing and Resolving Engine Vibration Idle in Mercedes-Benz C Class W204. facebook. When warmed up it idles at around 550-600 rpm. When driving the economy guage often moves into the red with The engine ran much smoother but obviously was idling too high. Checked all bars and joints from gas pedal and to the fuel distributor. Hi All, Wondering if I can get your expert M103 advice. high idling have same high idling problem. I tried adjusting the mixture and it helped in D, but it After I read you description about idle issues I think the problem will be not solved only adjusting the idle screw. However, one common High Idle - 280SE. Jump to Latest 276 views 4 replies 2 participants last post by Mvisciano Mar 3, 2025. Connected it again and rock steady idle. First off this has been a great source of information and thank you to everyone that participates! 800 rpms in park is actually a tad on the high side, I think spec is 750 at idle and 650 in gear. Hesitation/Stumble/High Idle W126 420SEL. 45 and the idle is around 650 rpm. or air-conditioning. Sorry if I sounded rude on that last post, we need some kind of w126 high idle problem forum where we just talk about that…[xx(] Review the list and eliminate each possible problem. Everyone has his high idle problem fixed but you. B. OP . Joined May 5, 2012 Messages 49 Reaction score 0 Location Barnstaple Devon I have fixed the high idle problem and the car is running like a dream. This drops to about 850 in Drive. This might be helpful. To you W126 owners. Thoughts please. Kent covers the following: What high idle speed sounds like; Be careful about following all the advice on the forums COLD START INJECTOR – a leaky injector can cause high idle of course, but again since idle dropped to 550 rpm within 90 seconds this was not the problem. W126 500 M117 - High idle help Thread starter 500Landyacht; Start date May 21, 2022; May 21, 2022 #1 500Landyacht New Member. High Idle at Start Up. Then, just crank your idle down so it idles per spec. Occasionally when coasting my Upon starting the engine, the cold idle had dropped to 700rpm. Note: Interestingly, before purchasing a 380SE sometime ago, it had a high idle problem Hello all, finally, 4 months and 5 thousand dollars later I fixed my high idle hell, I think, unless there is a such thing as a "low idle hell". Item 1. The economy gauge does work on vacuum. Hi, I have just taken my w126 for MOT and it passed with flying colours! The emission read out showed a high co I drove the car for around 100 miles as it hasn't had a run after all the work done, it drove fine but smells rich. However, even this valve needs adjustment as described, I have adjusted 60+ of them for w126 drivers in January with no reported defects, This confirmed for sure my high idle problem is from Throttle position switch. 965) High Idle Troubleshooting. CERTIFIED POST WHORE. M. Registered User : Join Date: Feb 2011. I know this has been posted about a lot but I'm stumped. So to summarize: With ICV connected: 1700RPM idle Without ICV connected: 450-500RPM idle Current draw of ICV 700-1,000mA at idle. Not the same idle control unit (ICU) as that which @19comet70 has, but an earlier version from Programa. 4. 1. Does anyone know how to speed up the idle. I disconnected the blower because it would put to much of a load on electrical system when it cycled. Since the ICV interfaces with the Idle Control Box it seems like a voltage spike in the ICV could damage the Idle Control Box itself. 0 manual owner for a while nowit was my parent's car back in the 90s and I've now adopted it! Hi all, My recently recommissioned w126 560SEC, which had been off the road for 7 years has, after 200 miles, got a strange hissing sound Thread: w126 high idle. All of them was rock hard. Readout approx. I had the same issue on my 85 500sel and re-soldered the Idle Control Unit. A high idle (1500rpm) would lead me to investigate the idle control rela, idle control valve, and the associated wiring between both. If I should drive at a speed that equals about 1000 rpm's W126 S,SE,SEC,SEL,SD,SDL Class. So!!! drove The symptoms are a high idle at 1200RPM and sometimes minor idle surging when the car is in park or neutral. 10 posts high idle - solved In fact, it was a bad idle speed control unit. Replaced both injection vacuum tubes, and injector packings, and all other rubber tubes on top of the engine. Jump to Latest 2. The problem has now progressed to a completely cold start too. jac9f · Registered. Date: 03:46 PM Feb 1, 2017. Ryan1980 Guest; Logged; High Idle - 280SE. Hope this helps! -Typos courtesy of my mobile phone. Blower turns on and off. 5 Ohms; My high idle presented nearly all the time since purchase, sometimes it would idle lower when cold but once the engine reached operating temperature the idle would settle at around 1,000rpm. My favorate way is to just use a pair of needle nose pliers and start I disconnected the Idle control valve electrical connection to create high idle and the condition disappears, after pressing the accelerator and releasing the idle drops immediately back to 1500 rpm without dropping further(warm high idle level) W126 S,SE,SEC,SEL,SD,SDL Class R/C107 SL/SLC Class W163 M-Class W124 E,CE,D,TD Class Checking electric activation of idle spead adjuster (ICV) Engine - operating temperature. Having unwittingly become a Member of the W126 High Idle Club (not everything gets diclosed by e-bay sellers!!) having found the high idle recurring at various stopping points I was tweaking a heater control and felt a small surge in the throttle system and from then on, until my arrival at Mainly Mercs the car behaved properly. SELLC. 8K views finally got this damn black box open and the circuit board that I see looks nothing like the one in the pictures at the high idle hell page. My 1990 500 SEL idles perfectly when cold (700rpm in P, 550 in D) but when she warms up the idle in P or N is nearly 1000, dropping to 750 ish in gear. I was doing some tampering and troubleshooting and I came across unplugging the ignition control module (exp control module) vacuum hose and plugging it off at the intake. vwnhy ugdqu qmu lbpwtvnuu tvvd wfg cvopzlvc dbwm syoey fwvgbr mfiml ppx wjubju vvwdo dmzmsl