ML 320 starts loosing power on highway - PeachParts Mercedes-Benz Forum

calookin · #1 10-15-2008, 09:43 PM

If I stop on the side of the highway and turn it off, then restart it, it seems to run great for a minute. It doesnt seem to be a problem when driving in town.

Any Suggestions?

mbdoc · #2 10-16-2008, 08:14 AM

Does the check engine light come on?

Most likely a misfire causing fuel injector shut-off.

sdanville · #3 10-16-2008, 10:57 AM

A crankshaft position sensor cured mine of that.

$80 and 5 minutes installation.

wait....the CPS made it not run, the crappy running was the $150 _ Mass air flow sensor.

calookin · #4 10-16-2008, 09:03 PM

Quote:

Originally Posted by M.B.DOC

Does the check engine light come on?

Most likely a misfire causing fuel injector shut-off.

M.B.DOC

Yes the check engine light is on. The ETS light has been on for a while also, but I dont think it has anything to do with this since this just started the other day.
It does seem like a misfire, but it also pings if I press the pedal to the floor.

------------------------------------------------------------------------
Cps
A crankshaft position sensor cured mine of that.

$80 and 5 minutes installation.

wait....the CPS made it not run, the crappy running was the $150 _ Mass air flow sensor.

Cps

how can I check to see if that is the problem?

Thanks
Charlie

sdanville · #5 10-16-2008, 09:12 PM

Buy a Mass flow air sensor and try it.

If it doenst cure it, you can resell it.

It installs in a minute.

some guys have had luck cleaning them . I had no luck cleaning mine.
In fact , I have an extra one in stock.

when my ignition wires started to fail I thought it was another MASS ( mass air flow sensor) and bought another one...but didint need it.

kept it as a spare. Its one of the weak spots on the ML.

wis · #6 10-18-2008, 12:59 AM

What year? some of the early mls had a fuel starvation problem with extended high load situations, there is an updated fuel filter and set of fuel lines to prevent stavation, ususally only shows up towing or on hills though. could also be catalyst partially plugged up. Usually air mass meters will cause a loss of power in the upper rpm/load range regarless of engine speed.

wis · #7 10-18-2008, 12:59 AM

What year? some of the early mls had a fuel starvation problem with extended high load situations, there is an updated fuel filter and set of fuel lines to prevent stavation, ususally only shows up towing or on hills though. could also be catalyst partially plugged up. Usually air mass meters will cause a loss of power in the upper rpm/load range regarless of vehicle speed.

calookin · #8 10-23-2008, 08:15 AM

Hi
I had a friend at a smog shop run the code and it seems that there is a misfire happening on cylinders 4, 5 and 6.
I was thinking it was a fuel thing too.
Charlie

mbdoc · #9 10-23-2008, 08:25 AM

With a misfire on the 1 side like that, MY first test would be a backpressure test on that side catalytic converter. That is the drivers side.

calookin · #10 10-24-2008, 10:36 PM

Quote:

Originally Posted by M.B.DOC

With a misfire on the 1 side like that, MY first test would be a backpressure test on that side catalytic converter. That is the drivers side.

M.B.
Yes, it was the catalytic converter. Thank You. Why the heck is there 3 on that side, and 2 on the other, I wonder. I have an appointment on monday at the muffler shop, BUT, I did hit the converters with a rubber hammer, and it seems to have made it a lot better.

Charlie

sdanville · #11 10-24-2008, 10:47 PM

my converters were replaced FREE by Mercedes under a recall or warrenty. Whatever it was it was FREE. and I had over 100,000 miles on my 99 ML320.

ygpms · #12 10-25-2008, 08:53 AM

sdanville

Did you receive a recall notice from MB? I have a 99 ML320 is my converter covered by this recall?

calookin · #13 11-08-2008, 02:58 PM

Hi All

OK, it wasnt the converters,or anything to do with the exhaust, a total backflow(?) exhaust test was done, and it had no problems. The shop owner said it has to be in the computer, or something.
It is back at the smog shop(a friend) and he is going to try to figure it again

Back to the problem;

It seemed to happen slowly to begin with, as I was on the highway. It was real bad on the hills. It seems to go away(for a minute) when the motor is shut off/restarted. It did seem to go away after I used a rubber mallet on the cats.
After the restart, it seems to be a time thing, as it seems that if I do a restart/go, or if I restart at a red light and let it idle till the green, it will only run good for less than a minute, either way.

After the rubber mallet abuse, It Did run good for the rest of the day, but the next day, it was back to the misfire.

calookin · #14 11-09-2008, 05:05 PM

Quote:

Originally Posted by ygpms

sdanville

Did you receive a recall notice from MB? I have a 99 ML320 is my converter covered by this recall?

No, I have not recieved a recall notice for anything that I can remember.