Hello,

I have a 00 ML 430 with 59K. This car appears to not have a lot of pick up for 8 cylinder with 268 HP. I am thinking that I may need to replace the spark plugs. I have replaced the MAF sensor due to my CEL coming on.
What do you think?

Hi Were the adaptations reset after you reolaced the mass air sensor,also is the engine temp going up you might have a restricted convertor,only other problem with the 430 ml was the fuel delivery system,have the pressures tested and amount checked.joeym

u know what? I am not sure. I need to call the repair shop and ask.

Hi touting, there are a number of reasons your ML may be lacking performance, but re-setting the adaptation/fuel trim numbers isn't one of them. In my shop we replace a few dozen AMM's every week, usually for CE lights and performance complaints. We NEVER re-set the adaptation numbers for a simple reason. The techs' here are required to road test the vehicle following AMM replacement. The adaptation numbers are then re-checked. If the numbers are falling back into specification we know the AMM was the problem. If the numbers are re-set it may be hard to tell if the problem is fixed.

In your case I'd simply drive from a standing start at wide open throttle. If you've got a partially clogged catalytic converter you may lose a few cylinders, especially at high RPM, and all on the same bank. I know it sounds crude, but it's a good way to eliminate the converter as a possible cause. Another possibility is the ME-SFI control module. I've got an ML 320 in the shop right now that came in lacking power slightly. We eliminated the fuel pump/filter, ignition system, and converters as possible causes. After we replaced the ME it ran great. I've seen a number of these in the last few years.

As far as the spark plugs causing power loss, I doubt it. You'd have mis-fire codes all over the place by the time they got bad enough to cause power loss. Of course, replacing them can't hurt either. In any event have your repair shop check it out. If they have the means to monitor the ME-SFI actual values (inj. duration, spark timing, etc. ) while driving the vehicle they should be able to fix it. Good luck.

Thank you for the info.

Now is the ME-SFI control module a costly item to fix?

Yes, about $1200, but don't run out and buy one until you're sure it's the problem. Let us know what happens.

How do you unclogg a catalytic converter?

You don't, you replace it.

I have a 2001 ML320. My latest catalytic converter
failed after 20,000 miles on it (MB part).

Could the ME-SFI control module cause it to fail?

__________________
Ralph Burnette
1993 300SD (286k + miles)
2000 SL500
2001 ML320

Technically speaking, yes. However the overwhelming majority of converter failures is due to the internals breaking up and restricting the exhaust flow on that bank of cylinders. In my opinion, this is simply a poor design that has nothing to do with engine management.