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Discussion Starter #1
First post, so sorry about newbie questions....I did try the search function.

99 S420 all regular maintenance has been performed. CEL came on this past week accompanied by an obvious miss. 151k miles on the odometer. OBDII codes read P0170 & P0173 (fuel trim whatnot). Time for a MAF cleaning methinks. Pulled the MAF and CRC MAF cleaner applied....let dry & re-installed without issue. Wah-la....perfect idle, drove around a bit and normal performance again....issue resolved...so I think. Shut her down, and went to restart - and she does start, but feels like running on 1/2 bank of cylinders with obvious misfire, ASR / BAS light comes on as does CEL again. This, after just having purred like a kitten !? Quickly shut her down, and OBDII scanned her and am getting P1580 now with a read-out of DTS codes not found ?

Any clues would be most appreciated.
PS420
 

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1993 190E 2.6, 1990 300SEL, 1992 300SE, 1992 400E, 1987 190E 2.6 murdered by my brother.
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Check the cheapest which is that all cylinders have spark. Does it only do this when hot? Get an old spark plug and pull each boot and touch the exhaust manifold while having someone crank the car and then quickly shutting it off. This is to check that each cylinder has spark. It could either be the spark plug wire(s), ignition coil, or your EZL which is the ignition control module which is very expensive. This symptom you describe can also be the crankshaft position sensor(s). The most expensive thing here is the EZL. That damn thing is like $2000 brand new.

Does it only do this when its hot? Gotta give more info. Are you using cheap ass gas? 91 octane or higher and only use Tier 1 gas companies....meaning Chevron, Texaco, Conocophilips66, Shell, Mobil 1.
 

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Discussion Starter #3
The only thing that has been done is cleaned the MAF. It was running perfect. Then the CEL came on with the P0170 & P0173 codes. I cleaned the MAF, and re-installed and started it up and it ran beautifully. I drove it around a bit to warm it up. I shut it off and re-started to make sure all was good, and that's when it first acted up, so yes it was hot when it first did it. I just checked it with a cold engine, however, and it is acting up cold as well. Acts like it's firing on only 4 cylinders. Plugs are good. Hard to believe it can be running perfect one minute with one shut down & re-start causing all havoc to break loose ! BAS/ASR light is on as well.

Not using cheap gas...always premium, usually BP.

Thanks for you help.
 

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1993 300SEL (Sold) 2007 X5
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You sure you plugged the MAF back in correctly?

Someone with a later W140 will have to confirm this, but if you un-plug the MAF the car will run on a closed loop with a set of predetermined values, if it runs fine then the issue is your MAF.
 

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1993 190E 2.6, 1990 300SEL, 1992 300SE, 1992 400E, 1987 190E 2.6 murdered by my brother.
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Sounds like its your EZL. I changed a lot of parts on my 300SE. Same symptoms. Fine when from a cold start. Shut off the engine and then restart it and it runs horrible. Now that the temps are colder, it wont even restart after it gets hot. My retired Mercedes mechanic said to check for spark when it is acting funny. Pull each spark plug boot out and use an old spark plug and ground it on the exhaust manifold. I had zero spark for all 6 wires and we just changed the ignition coil yesterday. Its the EZL. When yours start to act up. pull each boot and check for spark. if some have and some dont then it could be your spark plug wires. if all of them dont then its your EZL.
 

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1998 140.070 CL500, 1966 406.121 U65
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Sounds like its your EZL. I changed a lot of parts on my 300SE.
Given that a 1999 S420 does not have EZL, I think that could be difficult.
A ME1.0 M119 has coil on plug. For a coil to go wrong, only one of tops 2 cylinder
would be out of the loop. * you can figure out which cylinder is not on, by
disconneting one by one at a time. No change in pattern, cylinder is inactive *

S420, in you case, it seems like, that ME1.0 cannot determine fuel mixture for
one of the banks, left or right, and shuts down the entire bank.

P1580 is related to the step motor of the butterfly throttle.

Since startekinfo seems to have begun blocking access, I cannot give you
any more directions.

What happens when you turn on ignition to step 2, but without starting?
Do you hear sound from the butterfly motor, that it is resetting its position (you should)?

I do also support in running the engine with the MAF disconnected, to see if
it runs in a open loop mode.

Do also have a look at G-AMGs cleaning of the intake;
http://www.benzworld.org/forums/w140-s-class/1542031-photo-diy-complete-fuel-system-cleaning.html

br,
syljua
 

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Discussion Starter #7
Found the problem

Thanks for all the help & suggestions ! I screwed it up myself....which I do routinely !

When I cleaned the MAF, I took out the entire housing from the intake. On the re-install, since those dang hose clamp screws are so hard to get to, I slid the lower one around a bit, so I could access it easier the next time. Unfortunately, where I placed the screw was in the direct path of the throttle cam ! It obviously got out of sync and really messed things up ! So I put the hose clamp back where it was, and reset codes, etc., and it's back to running normal again. Cleaning the MAF was all it took to begin with, but my big idea of moving the hose clamp around was what screwed it up royally !

Again, thank you for your help !
Phil
 

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1987 230E silver W124 (sold). 1991 W140 400SEL silver.C280 W202 Silver (RIP) 2006 W203 C220 CDI
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On a similar vein, Ive just replaced the MAF, and the car is running almost as roughly...
Now, how do you reset the codes?

Visit MB?
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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for the car to adapt drive 20miles or so. to manual reset you need scanner or star diagnostics. on mine i dont like to do the reset so i can have the codes stored so i can see all the defects i had . i know that might sound stupid but it comes in handy once in a while (write the cause and repair with the error code). i only reset it once every two years because of smog check(btw i had the stupidest result on my smog report they failed it since my car threw a code about a window regulator. that one made pissed off and later laugh)
 

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1987 230E silver W124 (sold). 1991 W140 400SEL silver.C280 W202 Silver (RIP) 2006 W203 C220 CDI
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Thanks for that.... I might need to refuel, as she is giving me about 5mpg at the moment!!

So, a good half hour at highway conditions?
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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high way is good but did you install it properly? since it was suppose to automatically fix it self drive a mile turn car off drive another mile turn car off and before the third time leave the key to the position the indicators turn on for about 30secs. that worked on all of my benzs(except for the modern ones 30miles fixes it) if you still have another problem the cel wont turn off. btw is your wiring harness good? since you have a 91. and also did you clean the throtttle body?
 

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1987 230E silver W124 (sold). 1991 W140 400SEL silver.C280 W202 Silver (RIP) 2006 W203 C220 CDI
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MAF was installed by a mechanic, and checked by another...
The wiring harness is in good nick, and no I didnt clean the throttle body as it was pretty clean anyway according to the shop.

Now.... with the indicators, is that just the left/right turn signal or the hazards?

As soon as you reply, I will slip out and test it.

Ben
 

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1987 230E silver W124 (sold). 1991 W140 400SEL silver.C280 W202 Silver (RIP) 2006 W203 C220 CDI
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Nope. did not work.
Going to MB on Friday.

If that fails, Im taking it to the tip and walking away. Bloody heap of useless %^&*
 

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Nope. did not work.
Going to MB on Friday.

If that fails, Im taking it to the tip and walking away. Bloody heap of useless %^&*
hopefully the dealer doesnt charge alot. why not take it back to who installed it? they might have not installed it properly.and the dealer isnt the only one that could reset it your mechanic should be able to.
 
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