protonspring

New plugs and ignition coils. Same problem. F me *** in the *** behind the ***** on saturday ** under the ****.

This is getting ubsurd. Guess i will start over.

protonspring

Clogged exhaust? Low fuel pressure? Grasping at straws.

Hispeedlowdrag

Have you replaced the injectors ? I swapped mine around and it acted the same. I replaced them anyway along with all the other stuff. How about the 02's ? I swapped mine, no change and yes, I replaced them anyway. Maybe a cat is beginning to fail ?

protonspring

I will remove the o2 sensors tomorrow and see if anything different happens. The computer should use default values.

It wont run great, but it shouldn't misfire.

protonspring

And yes. still old injectors.

I would like to replace stuff one step at a time.

protonspring

Disconnected o2 sensors. Same thing.

If i unplug the fuel injector for #8 or the ignition coil, it misfires immediately (does not wait 30 sec). Stands to reason the spark plug and ignition coil are working fine.

Hispeedlowdrag

I agree on replacing one part at a time, I would have done the same except the price of the parts in Canada, if you can find them, is double what is in the US (even after $ correction) so I get them shipped from our great southern neighbors. Shipping one thing at a time becomes expensive so I just did it all at the same time and with 200,000K on the car I figured it was due.
Hope you get it figured out soon. Curious to find out what the gremlin is.
You mentioned you checked and swapped plugs. How were the gaps and color?

protonspring

All of the plugs and coils are new. Car has 110k miles.

protonspring

Crankshaft trigger wheel looks fine. There is a gap every revolution, but i think it is normal.

mbwillgrubs

It is the time that strikes me as the dominant clue. There is something that is being triggered at 30 - 40 seconds that is causing your misfire on #8. Somewhere there is a map of what the engine does when it starts and runs initially. Run this profile, turn this on, turn that off all based upon sensor feedback and run time.
BenzNinja may know but I don't know how to ask him. Otherwise I would spend some time (not that you haven't spent time already) finding that operating map/profile. Again, I know the frustration (felt it on a Jag I mentioned). We are wishing you the best.

protonspring

New fuel injectors in the mail, but i won't get them until after I leave on a work trip. I will test again in about 2 weeks.

protonspring

All new fuel injectors. Same problem.

mbwillgrubs

Look at post #7 regarding misfire in multiple cylinders currently showing in the W211 AMG forum. It may be of interest.

protonspring

here?

https://mbworld.org/forums/w211-amg/871324-e55-misfire-cyl-2-4-7-8-a.html

mbwillgrubs

Yes, it has a discussion regarding adaptation of the control unit after changes to some components and after misfire events.
I think the big thing is getting your machine on a Star system to see what it might say. I have two MBz and signed up for BenzNinja's program. Having that tool is invaluable, especially for what you are going through.
I know you are loath at this point to spend any more money but maybe someone around you has a system?

protonspring

i found another local shop that specializes in german makes, so i decided to give them a shot. Will report of they find anything.

protonspring

Some updates: New shop says compression is perfect, spark is perfect, fuel is perfect. No computer errors except for misfire on cylinder #8. OK. So now, we're all in agreement.

Next step is a leakdown test and pressure profile for cylinder #8. Should complete by the weekend.

JohnLane

OP monitoring intake vacuum as it misfires will speak of whether or not a weak cylinder is pumping air as it should.

Cam lobes healthy and happy?

Misfire only at idle means it has lots of time (relatively) compared with a misfire at 3000 rpms.

Plugging into XENTRY will be a worthwhile endeavor. Clearly you are handy with the car. Having the real MB system with a BenzNinja membership is money well spent.

protonspring

Well. . good news. . shoutout to Import Auto in Logan, Utah for finally fixing!

After verifying that all the hardware is in order . . . . . (perfect pressure waves, etc.). . . . .

I'm sure I'm saying this wrong, and I don't think they totally understand either, but it there are adaptations in the ECU that learn timing imperfections in every cylinder. For one reason or another, these "adaptations" can get off. Perhaps someone changed the ECU in the past without resetting these. Anyway, the misfire has totally gone away (according to them, and not yet verified by me), after resetting these adaptations. The ECU should still monitor and learn over time and shouldn't have any more problems.

Here's to hoping!

protonspring

So. . likely, the engine wasn't really "misfiring" per se, but because the timing of the ignition in cylinder 8 was too far off from where the ECU expected it to be, the ECU flags a misfire. . . . this is really at the millisecond level.

Hispeedlowdrag

Congratulations on getting that solved and thanks for the update. Do you know what they did to "clear" or "reset" the ECU ?

protonspring

No. . just Mercedes STAR software has the option somewhere to analyze/reset. It has to do with individually calibrating every cylinder.

protonspring

Now misfiring on cylinder #4. Did all the basics and always on cylinder #4.

Back to the shop again.

mbwillgrubs

Does ambient or engine temps make any difference?

protonspring

No. misfires after 30 sec. Same behavoir.