Please help; my 1998 E320 runs perfectly all the time, except after restarting the engine when engine is warm, if I push break really hard to full stop, the engine will cut-off. (I can see the rpm up and down then stops). When AC is on, make it even worse, but after a few minutes or a few start/stop, it will run just fine again.
I replaced Crankshaft Position Sensor and Mass Air Flow Sensor - they do not solve the problem.

 

maybe the trans is causing it, possible torque converter. or some major vacuum leaks on the engine, is the air cleaner in decent shape? seems either car is choking for air or an issue between trans and engine.

 

Thanks for your suggestions.
(1)The air-cleaner looks fine (very "white"), I will swap with my other 1999 E320 wagon, which does not have same problem .
(2) The engine cut-off never happened when engine was cold.

Anything I can check and try?

 

I would go back to crank position sensor or Throttle valve body actuator. Both of them may or may not show up as a misfire CEL P0300-P0306. Tolerances were exceeded streight from factory causing engine surges and misfiring at iddle. There is a buletin on alldata from Mercedes about it. I found it in 1999 ML320 section and they also list all affected serial #s of throttle valve actuators.

 

very weird problem at the dealership i would start by putting a fuel pressure guage on it and tape it to the windshield and drive the car to see what happens to the fuel pressure when your condition happens. are there any codes in this also when you replaced your ckp sensor and air mass did you reset your fuel trim adaptions just a few other things you may want to check. it even sounds like you may have some kind of loose connection or some sort

 

Hi vytamenc,
How do you reset the fuel trim adaptation after replacement of crank position sensor?
Thanks, Bernard

 

Thank you all, I will keep monitoring the items you mentioned; I noticed my 1998 E320 Sedan, the reading in ACC Head unit, Item #21: Engine Speed, e.g 0099(x100) correspond to 9,900 rpm, - the reading is jumping between 42 and 255, such as 42-255, 66-255, 53-255, depending on the car speed, when the car is idle, it’s jumping between 42/255 most time. The other 1999 E320 Wagon stays at 32 while idle, is it because of year of 1998 and 1999?

When 1998 sedan is cursing, it’s about 700-750 rpm without press the gas paddle, when it’s waiting at stop sigh (at D-drive position), the idle drops to around 550-600 rpm (it seems very closed to the 1999 WGN), if I do the sudden full stop, most likely the 1998 engine will die – it’s worse when the A/C is on.

 

Hi, vytamenc, Bernard,
(1) I would love to know how to do "...ckp sensor and air mass did you reset your fuel trim adaptions ..." too.
(2)What items I can replace in this Fuel related problems?
(3)Will any fault item cause ACC #21 changes between 42/255, 55/255,...
Thanks.

 

Hi, both of your engines should have same throttle valve body. If your fuel pressure is good, I would swap these two between and see how they idle then.
I did nor reset anything after CPS replacement, that is why I was trying to ask vytamenc
on this procedure. After replacement, I use to get CEL with misfire on at least one cylinder and now after a month of calm driving, I floored it a couple of times reaching 6000 RPM with no problem but I still feel irregular idle and engine surges when warm.
" Throttle valve actuators with production date from 662xx to 769xx are affected with production tolerances exceeded". Take a mirror and check date code on you throttle valve body cover to see if it is not one of them.

 

I did not have chance to replace my E320 throttle valve, but I did lose the black hose (torx crew), used the Carb Cleaner to spary into the the valve - so far, for a month, it has not happened yet. I will keep eyes on it - because it happened in the summer time more often while A/C was on.