W124 E420 Bogging - PeachParts Mercedes-Benz Forum

jkazzoun · #1 12-14-2009, 11:25 AM

I've done several searches and found some possibly related info, but nothing on this engine that quite fits.

Our E420 (1994) bogs under hard acceleration (and more and more under moderate acceleration).

The check engine light is not coming on, we've replaced the wiring harness, MAF, plugs, wires, caps (etc) in the past 12-24 months. Check engine light came on for all the other issues, not for this at all. No recurring codes either.

It's been to two mechanics, the second of which has looked at it for a week and had the head mechanic from another Mercedes specialist look at it (that makes three shops). All are experienced with this model. One is a MB only shop, one does 75% MB's and one is a 'Euro' shop. Lots of MB's, Volvo's and BMW's.

He said there were some old codes from the MAF, but nothing recent and does not think that's it. They've checked the fuel pressure, vacuum hoses and fuel delivery hoses, everything in the air/fuel management system, changed in and out a few modules, etc. Nothing...

He's telling me he's stumped and perhaps have the dealer look at it. However, neither he nor I really think they'll know (How often do they service these vs. newer models?).

The one thing I saw searching were some 6 cyl W124's with dirty fuel distributors.

Any ideas at all?

ps2cho · #2 12-14-2009, 12:54 PM

Have you ruled out injectors?

jkazzoun · #3 12-14-2009, 01:07 PM

Clogged or bad?

I don't think either (though he may not have mentioned it). I'll ask.

Thanks.

jhodg5ck · #4 12-14-2009, 01:51 PM

has anyone inspected the ETA harness? Just had a 94 500SL in that wasn't running right, no codes, but the ETA harness was Toast.

fresh Beckmann ETA, reset adaptations and all is well!

Jonathan

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Now playing: Band Of Horses - The Funeral
via FoxyTunes

jkazzoun · #5 12-14-2009, 06:20 PM

So, the mechanic called back again this afternoon and says it runs fine now, though he has no idea why. He did fix some leaks around the fuels pumps, though he said fuel pressure was fine.

One guy there thinks it's bad fuel from the station across the street and that several people have had problems because of that. However, I don't buy it. It's been going on a while and we've gotten gas at several places.

No guarantee this thing won't come back all of a sudden (I think it will). Maybe it is the eta and they just bumped it. Who knows...

I'll report back if it returns and we actually learn something. I promised the mechanic the same...

jkazzoun · #6 12-14-2009, 06:26 PM

@jhodg5ck

Thanks. I think they did. They asked me about the main harness while I was there and seemed to be inspecting all.

I think they were quite thorough. They've put about 10 hours into this thing (they billed me for three, replacing brittle vacuum tubes that cracked, the fuel leaks, etc.).

hanno · #7 12-14-2009, 06:27 PM

For what it's worth, I was playing parts swap trying to pin down an ABS issue on the 87 (solved!). To get to the ABS module, the ECU had to be removed/installed. When all was done and car restarted, it idled low, would bog upon giving it throttle, but clear up and run at high RPM. I had installed the electrical connector on the ECU but not all the way (some pins connected, some not). Another 1/4" and latched down and all was well.

jhodg5ck · #8 12-14-2009, 06:33 PM

Quote:

Originally Posted by jkazzoun

@jhodg5ck

Thanks. I think they did. They asked me about the main harness while I was there and seemed to be inspecting all.

I think they were quite thorough. They've put about 10 hours into this thing (they billed me for three, replacing brittle vacuum tubes that cracked, the fuel leaks, etc.).

That's good.. Sometimes MAF's on these cars Won't throw codes even though they are acting up.. Pays to have good used to swap.

I'd ask if they did an injector test (in SDS)...I'm guessing they checked the fuel pressure reg..

Sometimes it pays just to unplug and reconnect everything, ie wires/modules/relays etc.. A bit of corrosion can cause Strange things to happen!

Jonathan

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Now playing: Dave Matthews Band - Let You Down
via FoxyTunes

simonshearer · #9 12-14-2009, 06:48 PM

"bog"

73Elsinore · #10 12-14-2009, 07:27 PM

Quote:

Originally Posted by jkazzoun

replacing brittle vacuum tubes that cracked

Were those the 6L6GC's or KT66's? Every 400E has (6) KT66's in the output stage. You need those for maximum distortion

Sorry, couldn't resist!! I saw 'vacuum tubes' in your post and my pea brain just switched gears on me... crawling back under my rock now...

jkazzoun · #11 12-14-2009, 07:46 PM

@Simon -

Bog - Action: Push accelerator Result: RPM's and vehicle speed reduce.

We'd have to then accelerate very gently to build speed again.

@73E - They pulled them from a Quad II.

73Elsinore · #12 12-14-2009, 08:02 PM

Quote:

Originally Posted by jkazzoun

@73E - They pulled them from a Quad II.

Right on!

jkazzoun · #13 03-13-2010, 04:31 PM

AAAAAAAAAARRRRRRRRRRGGGGGGGGGGGG!!!!!!!!!!!!!!!!!

So, car got worse soon after this post. We had it looked at again and it was narrowed down to "likely" be the ETA. So, I sent the ETA to 4Mercedes, who had rebuilt it over 3 years ago. They checked it, said the motor was bad, rebuilt it, including new cable/harness and sent it back. Installed today and it runs worse than ever.

Can't do much over 30. If I put my foot into it, it goes into limp home. Barely made it home. 25 MPH on freeway, stalled crossing busy intersection.

So....

Does it need to be reset after installing the ETA? Could the throttle module be bad?

Signed,

Very, very frustrated in Austin

PETERPNYC · #14 03-13-2010, 05:28 PM

Quote:

Originally Posted by jkazzoun

AAAAAAAAAARRRRRRRRRRGGGGGGGGGGGG!!!!!!!!!!!!!!!!!

So, car got worse soon after this post. We had it looked at again and it was narrowed down to "likely" be the ETA. So, I sent the ETA to 4Mercedes, who had rebuilt it over 3 years ago. They checked it, said the motor was bad, rebuilt it, including new cable/harness and sent it back. Installed today and it runs worse than ever.

Can't do much over 30. If I put my foot into it, it goes into limp home. Barely made it home. 25 MPH on freeway, stalled crossing busy intersection.

So....

Does it need to be reset after installing the ETA? Could the throttle module be bad?

Signed,

Very, very frustrated in Austin

I had something similar and brought it to 2 Mb tech till we found out it was the coils.

400 SEL BREAKING UP AROUND 1500 RPM

Prolly easy enough to pull and see if there is white arcing on it before you spend any money

400Eric · #15 03-14-2010, 12:22 AM

Is this an ASR car? ASR cars get all kinds of funky troubles that are impossible to figure out.
Regards, Eric