m119 Idling adjust-PLEASE!!!
 

I've been noticing that my idling is quite low esp. when in traffic @ 90 degrees and on "D" and A/C on~ 500-510 RPM's- Has anyone adjusted their idling on these engines before??? It usually idles well when cold (650-700 rpm) -- but after driving for about 30 + mins, then it goes down to the 500's. It just concerns me beacuse if the idling is too low, the oil pressure drops as well... :eek: Not the prettiest site to look at. PLEASE --any suggestions are welcome!!!!

For M119 engine, its idle is controlled by ECM, I don't think there is any idle rpm adjustment should be made.

There is still a way to increase idle rpm, by adjusting a plastic screw in the throttle linkage can do that, this actually adds tension in the linkage and is equivalent to applying some gas pedal pressure all the time, it can mess up the engine control and should not be attempted.

500 rpm of idle when warm is quite normal, lower oil pressure at idle is normal as long as it's higher than 0.3 bar and it increases when rpm is up.

You can increase oil pressure by using heavier engine oil, when I had 10W30 my oil pressure at idle was 0.4 bar, my idle is now 1.3 bar with 15W50.

I agree completely. My oil pressure also increased from 0.5 bar to 1.5 bar once the switch to Mobil 1 15W50. My idle speed is also around 500 rpm when warmed up.

I HIGHLY recommend synthetic oil (of the proper viscosity) in the M119 engine. You want to give the valve train, including timing chain, every advantage. A valve job in an M119 engine runs about $6000! Also, these engines tend to run a bit hot, esp. in a W124 body.

Do not adjust this with the cable!!!!! The accell pedal has a switch on the bottom that tells the computer if the engine is supposed to be at idle. This can cause major problems. This setting will also tell the computer when the engine is in decel mode (and get better fuel economy).

idle adjustment
 

I appreciate all the input. I also read in The Star magazine, that there is a chip that would actually inc. idle to 600+ instead of the 500+ of the original equip. setting. And it's an original MBZ replacement component. Murphy's law, I forgot what issue that was.... :( I f anyone out there knows what I'm talking about. I would great appreciate the info.

Regards

a2, the idle is supposed
 

to be around 500rpm at those temps (90F) and a fully warmed engine. Also your oil pressure is ok! Don't fix it, it ain't broke!

Mercedes Idle Speed vs Coolant Temperature

Temp (C) ---- Trans in Neut (rpm) ------ Trans in gear (rpm)
< 0 ------------- 800 - 900 --------------- 750 - 850
0 < 30 ---------- 700 - 800 --------------- 650 - 750
>30 <40 --------- 650 - 700 -------------- 550 - 650
> 40 ------------- 650 -------------------- 500

Just in case the '>' signs confuse anybody, "> 30 <40" means "greater than 30 degs C and less than 40 degs C".

As you can see, after the engine is at operating temperature your idle should be around >500 and < 650. My car idles at 626rpm.

jimF
 

JimF,

When you say 626, is that in gear"D" or in neutral ??? A/C on or off? Thanks for the info... what a relief!!:)

sorry. . ;
 

should have said so! Another senior moment!

When fully warmed, with trans in PARK, it's 626-636. Never measured it in DRIVE because I made the measurements using the AST Retreiver (scanner) employing their LIVE DATA feature. I would guess that it's 525rpm or so in DRIVE.

jimF,

Those are the exact numbers I have on my M119...THANK GOD!!!

Big thanks to Benzmac, carman 850, 400E and JimF!!

Now it's drain the Mobil1 10w-30 and in with the 15w-40:D


regards