Rough idle/stumbling/falling over, issues during WOTs

[dionphaneuf]

I'm trouble shooting a low speed drive ability issue on my 92 500E w 245k mi. The issue manifests itself mostly at low speed and idle in D, but also in P/R/N, with the car struggling to stay above 500RPM when stationary and then lurching a bit at low speed and sounding quite rough. Once or twice it's even just shut itself off at low speed. This has also periodically been an issue on the freeway: it doesn't pull very strongly/does so unevenly, and it frequently feels dead until above 3kRPM. It also sometimes refuses to kick down.

To date, here's what I've done

• Caps and rotors are new in the last year or two. Bosch caps, Dudoco rotors, new insulators, new oil seals. Typically dry in there.
• Plugs at 1mm gap
• New NSS
• CPK is about 10 yrs/35k mi old and is good brand.
• Confirmed that the cats are clogged and need replacing. This explains some of the freeway behaviour but I don't think it would explain the low speed issues.
• Codes checked today after clearing a while ago
  • LH, ABS, ACC, STS are all Code 1 only
  • Pin 7 EA/CC/ISC is code 6
  • Pin 8 Base Module is code 12
  • Pin 17 EZL is code 8
  • Pin 19 Diagnostic Module is code 12
• New battery for general posterity

This has been going on for 3 or so months with varying levels of severity. The car does sound/smell to be running a bit rich but I don't know the best way to confirm this.

 

[gsxr]

DM code 12 (O2 sensor) is odd, with zero faults on the LH (pin 4). Can you clear everything and check again after a test drive?

Also, any chance you have access to a digital scanner / SDS / HHT-Win to view live data?

Pin 7 code 6 (NSS)... make sure the NSS is adjusted properly, and the shift linkage bushings are good on both ends of the rod.

 

[dionphaneuf]

I read these (and cleared) after my O2 sensor removed exhaust pressure testing drive so the DM code 12 is most likely an artifact of the prior 10 mile drive sans O2 - will drive to work tomorrow and test again afterwards and confirm.

I neglected to mention that when replacing the NSS I also did the shift linkage bushings. Front is super easy, rear is a huge PITA - I don't have the pliers and there's not enough room in the tunnel to use the socket + bolt method. I ended up slitting the bushing and installing it that way. I...thought I adjusted the NSS properly per the FSM instructions? I ensured the trans was in N and the NSS pivot arm was aligned w the guide hole on its body. Is there another way to adjust it? How does one check if it's properly installed 'live'? Or do I just tweak and then check codes?

@Jlaa has been extremely patient and let me use his scanner tool; the lack of a clear gear signal pointed us to the NSS and the weak battery voltage pushed me to replace mine. FWIW this battery for $187 on Prime arrive on my doorstep in 1 day and included a very nice 'Made in Germany' sticker, looking suspiciously like the OEM battery the PO had put in the car.

I'm going to replace the cats though and see what happens - fwiw they passed the 'bang' test as best as I can tell but obviously are restricting things.

 

[gsxr]

AH, yes, the drive with O2 removed will cause that fault code - clear those again, and they shouldn't come back, if your O2 sensor is connected tightly.

NSS, follow the instructions in FSM job 27-130. Disconnect shift rod, loosen mounting bolts, insert 4mm wire/pin/whatever, tighten bolts. You can verify the NSS adjustment with @Jlaa's SDS, view live data for E-GAS in HHT-Win as you move the gearshift to each position. The live data displayed should match the gear lever position.

Delco battery... yup, I have one of those too! There are only 2 or 3 battery mfr's supplying the USA. Very likely the same battery as OEM with a different label applied. FWIW, the nEverStart AGM 49 that I saw in Mal-Wart a couple months ago was also Made in Germany. (!)

Bummer about the cats. Would be nice to replace with good used ones, but that's basically unpossible without buying an 034 parts car just to get the cats from it (and hope for the best). New cats will make a pretty good improvement in high-RPM power.

 

[maw1124]

Bummer about the cats. Would be nice to replace with good used ones, but thats basically unpossible without buying an 034 parts car just to get the cats from it (and hope for the best). New cats will make a pretty good improvement in high-RPM power.

I'm suspecting 02 sensors, since the computer is dumping too much fuel, which means the O2 sensors are seeing lean condition. Spark seems dealt with, and failing fuel pumps don't go with running rich. So this leads me to O2 sensors (and maybe not even cats if they're not rattling).

maw

 

[gsxr]

Forgot to mention: Clogged catalysts don't always rattle. They rattle when the honeycomb breaks up, which can cause clogging... but you can have an intact honeycomb that is clogged. The backpressure test at full throttle is concrete proof.

 

[Jlaa]

AH, yes, the drive with O2 removed will cause that fault code - clear those again, and they shouldnt come back, if your O2 sensor is connected tightly.

NSS, follow the instructions in FSM job 27-130. Disconnect shift rod, loosen mounting bolts, insert 4mm wire/pin/whatever, tighten bolts. You can verify the NSS adjustment with @Jlaas SDS, view live data for E-GAS in HHT-Win as you move the gearshift to each position. The live data displayed should match the gear lever position.

Delco battery... yup, I have one of those too! There are only 2 or 3 battery mfrs supplying the USA. Very likely the same battery as OEM with a different label applied. FWIW, the nEverStart AGM 49 that I saw in Mal-Wart a couple months ago was also Made in Germany. (!)

Bummer about the cats. Would be nice to replace with good used ones, but thats basically unpossible without buying an 034 parts car just to get the cats from it (and hope for the best). New cats will make a pretty good improvement in high-RPM power.

Just curious… Would there have been a certain test to look at with the SDS to determine if the catalytic converter were plugged? Such a test, which I do not know if it exists, would have obviated the need to use a back pressure tester in the O2 sensor hole to determine it.

 

[Jlaa]

Im suspecting 02 sensors, since the computer is dumping too much fuel, which means the O2 sensors are seeing lean condition. Spark seems dealt with, and failing fuel pumps dont go with running rich. So this leads me to O2 sensors (and maybe not even cats if theyre not rattling).

maw

Question… If the car is injecting too much fuel, then how does one rule out oxygen sensor versus mis calibrated hot wire, airflow meter?

 

[gsxr]

Just curious… Would there have been a certain test to look at with the SDS to determine if the catalytic converter were plugged? Such a test, which I do not know if it exists, would have obviated the need to use a back pressure tester in the O2 sensor hole to determine it.

Great question. I do not know. It would be interesting to monitor MAF readings along with intake pressure readings, and compare those between a normal car, and one with plugged cats. I suspect there could be a way to make an educated guess about cat health based on this data.

Question… If the car is injecting too much fuel, then how does one rule out oxygen sensor versus mis calibrated hot wire, airflow meter?

Not sure if there is an easy way to tell. O2's are cheap and if it's old or original, a new one is a good idea. Only way I know to test the MAF is to look at readings at various RPM's at no load, and see if those are in the right ballpark. Usually, MAF's have a "hard" failure mode. Still, if your car is running well, it is a good idea to document "normal" values for your particular car, since you have SDS available. This data can be very useful for future diagnostics.

 

[maw1124]

Question… If the car is injecting too much fuel, then how does one rule out oxygen sensor versus mis calibrated hot wire, airflow meter?

Yeah, I don't know. My method would be to just replace them and see, since they're likely old and because he's ruled out spark and rich running rules out fuel delivery. Upside (especially since his cats aren't rattling) is it possibly saves changing cats. Maybe he ends up needing MAF too -- cannot tell. Not exactly @Jlaa approved engineering science, but there's a certain painless upside logic to it, which appeals to me. The native problem is, in a fuel + air + spark regime, air is the toughest one to nail down, because too much air could be coming from anywhere, including a sensor or a computer.

maw

 

[gsxr]

Yeah, I dont know. My method would be to just replace them and see, since theyre likely old and because hes ruled out spark and rich running rules out fuel delivery. Upside (especially since his cats arent rattling) is it possibly saves changing cats.

He posted in a separate thread (link here) that the cats failed a backpressure test. They're plugged.

 

[dionphaneuf]

I am tempted to grab an o2 sensor and put it in as it does smell rich. Not sure cheapest current source for these but my current o2 sensor is only 35k mi old (replaced in 2015). That said new cats will probably be another $1600 and be the big ‘work’ item for me this year on this car tho I may yet do starter, radiator, and steering box…

 

[maw1124]

Oops. I wouldn't replace those O2 sensors. I forgot about the back pressure tool post. I can't understand why plugged cats would create a lean condition, unless the air that's supposed to go out through the exhaust is still stuck in the stream where the sensors are. As I think of it, that's probably it. Have you tried running the car with open exhaust just before the cats? I forget whether these exhausts were clamped or whether you have to cut. If it runs well that way, then you know that both the high RPM and low RPM problems are the plugged cats. I think I'm almost certain that's the case. The air that's supposed to escape, isn't, so lean condition dumps more fuel.

maw

EDIT... stop me if I'm wrong, but on this car you'd only put the cats back in for environmental responsibility or originality, correct? When I went to do my '92 car, I didn't need to because there would be no CEL but I did it anyway for environmental responsibility.

 

[dionphaneuf]

On second thought, I'm going to hold off on making any changes to the emissions system until the new cats are in

 

[gsxr]

I think he may be located in PRK where de-catting is, ahem, frowned upon.

I don't think plugged cats will significantly affect mixture formation. You can get a rough idea of mixture issues by looking at the adaptation values. If they are skewed high or low (beyond normal ranges), that's another indication something is up with the mixture.

 

[dionphaneuf]

A local shop is offering me these cats plus install for $1300....they seem wrong? I'm likely just going to go w the magnaflow mentioned above and pay $500 (!!!!) for install.

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Other option is to upgrade my Fleiben CAT back only system to the full length...but that'll cost about $3500 once Cats are added in.

 

[gsxr]

A local shop is offering me these cats plus install for $1300....they seem wrong?

Shop buys the cats for $500 and charges you $800 for <2 hours of installation... seems about right, for them.

I'd shop around.

 

[maw1124]

These guys are smokers. If you've shopped install quality, I'd go with your preferred installer and the Magnaflow cats. Unless you're selling some restored museum piece, the car running well will be worth much more than which exhaust you're running. You don't want them ugly, but they're actually not in a beauty contest.

maw

EDIT: Keep in mind if you ever sell it and it leaves Cali, the next buyer is likely to straight pipe it (or X-pipe it) to Magnaflow mufflers anyway. Is there some weird California premium built into the $800 or is that the "Classic Mercedes Tax" to make it look gorgeous? What's going on with those price differences?

 

[gerryvz]

I don't know that @5thscaleracer & Flieben is still offering cats.... are they?

 

[Jlaa]

I dont know that @5thscaleracer & Flieben is still offering cats.... are they?

Got this in January 2023 from JC (California compliant Magnaflows) .... he had to redo the jig to switch from Airteks to Magnaflows ...... and we determined along the way that Walkers didn't work w/ his jig. That being said currently it is March. Not totally sure if JC is still offering cats or not.

 

[maw1124]

Got this in January 2023 from JC (California compliant Magnaflows) .... he had to redo the jig to switch from Airteks to Magnaflows ...... and we determined along the way that Walkers didnt work w/ his jig. That being said currently it is March. Not totally sure if JC is still offering cats or not.

[ATTACH alt=IMG_2551 Large.jpeg]162809[/ATTACH] [ATTACH alt=IMG_6489 Large.jpeg]162810[/ATTACH]

Those are purrrrrty...

maw

 

[gerryvz]

Got this in January 2023 from JC (California compliant Magnaflows) .... he had to redo the jig to switch from Airteks to Magnaflows ...... and we determined along the way that Walkers didnt work w/ his jig. That being said currently it is March. Not totally sure if JC is still offering cats or not.

[ATTACH alt=IMG_2551 Large.jpeg]162809[/ATTACH] [ATTACH alt=IMG_6489 Large.jpeg]162810[/ATTACH]

I was thinking of what 5SR said in this post:

2022 500E exhaust run | High-Performance Modifications

I have a small back log of customers requesting for exhaust kits. So we will be doing a small batch run of 10 possibly 20 or more if there are additional people who want to join. ETA will be in June/July of 2022 Due to material cost increase (lack of raw material production) prices have gone...

www.500eboard.co

 

[dionphaneuf]

Checked codes after about 80mi of driving today. Mostly good news

• Pin 17 EZL returned 8 again - I cleared it successfully tonight, not sure if it didn't clear properly last time
• Pin 19 returned code 5 which I can't clear.

Otherwise 1's everywhere else.

 

[gsxr]

Checked codes after about 80mi of driving today. Mostly good news

• Pin 17 EZL returned 8 again - I cleared it successfully tonight, not sure if it didnt clear properly last time
• Pin 19 returned code 5 which I cant clear.

Otherwise 1s everywhere else.

Pin 17 EZL returned 8: This is the O/L switch at the transmission. Pretty common failure. Check the wiring first, if it's ok, replace the switch. This only causes a slight hiccup at redline during a WOT upshift, nothing else.

Pin 19 EZL returned 5: DM codes sometimes will not clear until after the engine is restarted. If this keeps recurring, check all the EGR stuff... vacuum lines to solenoids behind the passenger headlight and back to the valve, the valve itself, and the intake tube below the valve. This will not cause running problems, just the annoying code and CEL, assuming the EGR is stuck closed / non-functional. If stuck open, it results in a rough idle, all the time.

 

[gerryvz]

That Code 5 on Pin 19 (the EGR code) is likely a broken / failed vacuum line. I lived with that irritating code for years until I discovered it was a simple vacuum line that was cracked in half due to heat and age.

It's a good idea to check all of the hard vacuum lines and rubber elbow connectors. I bet you'll find the culprit. It's not that common for EGR valves to fail, to be honest (though it can happen).

 

[dionphaneuf]

Awesome, thanks. Was glad to see that pin 7 code 6 was gone, confirming a 'good' NSS install.

On the O/L switch, anything in particular to look at on the wiring/any good way to rule it out vs the switch itself? Looks like a slightly annoying install but slightly easier access than the NSS. I'm tempted to leave it as is.

I've had that code 5 for a while. I'm 99% sure it's crap in the egr passages vs the vac lines or valve itself - it doesn't stumble when I pull vacuum on the EGR and I've tried two EGR valves. I need to get my heads on some good EGR/intake cleaner, let it soak for a while, and then roto root it again.

 

[gerryvz]

Ive had that code 5 for a while. Im 99% sure its crap in the egr passages vs the vac lines or valve itself - it doesnt stumble when I pull vacuum on the EGR and Ive tried two EGR valves. I need to get my heads on some good EGR/intake cleaner, let it soak for a while, and then roto root it again.

I thought the same thing, again for years, that I had a plugged passage in the intake manifold or whatnot. When I removed my intake manifolds in 2020, they really weren't gummed up at all.

It ended up being a broken vac line, as I mentioned. Do yourself a favor and check your lines + elbows, if not replace all of them outright. A cracked elbow is not really apparent until removed and flexed, which is why replacing everything is such a good idea after all these years (if still original).

All of this stuff (including all of the electro-vacuum valves behind the passenger headlight) is all detailed in my 2020 Top-End Refresh thread.

A couple of relevant posts:

Here

Here

 

[dionphaneuf]

Could you make your car ‘stumble’ at idle w a Mitty vac on the EGR at idle?

 

[gsxr]

Could you make your car ‘stumble’ at idle w a Mitty vac on the EGR at idle?

Normally, yes. Apply full vacuum directly to the valve and the idle should change from smooth to rough.

With the engine off, and full vacuum applied, yank the hose off the valve. You should clearly hear the valve snap closed.

As Gerry said, valve failures are pretty rare. Usually the issue is on the control (vacuum) side, the rest of the time it can be a plugged tube to the intake.

I found the nice mess shown below in one of my cars. The EGR was still working fine, but since I had the ETA out for replacement, I cleaned up the mess.

 

[dionphaneuf]

Ah good point - I pulled my ETA a year ago when I put the Don unit on but didn't do this, will try that now that my ETA removal technique has much improved following two or three junkyard ETA removals. Just throttle body cleaner did the trick?

 

[gerryvz]

As shown in my Top-End thread, I did have some blockage at the ETA, but it wasn't all the way through as I thought it might have been before I did the job. I have some photos showing the blockage and the clean-up of the tube when I disassembled the intake manifold and removed the ETA. It would be in the first, second or third post of that thread.

On the M104, it's much more notorious for blockage. I also have photos of the EGR tube in my former M104 engine and it was completely blocked, so when I pulled and refirb'd the cylinder head I cleaned out that tube as well. Again, 100% blockage due to the design on those cars.

 

[gsxr]

Just throttle body cleaner did the trick?

Lots of scraping to remove the thick goop, then use rags or paper towels soaked with solvent to wipe it all down. Throttle body cleaner should work fine. If you have an excuse to pull the manifold that would be even better, but then you're looking at a several-month top-end rabbit hole like GVZ went down years ago!

 

[dionphaneuf]

It's an epic battle between the scope creep and the check engine light getting at my OCD

 

[gerryvz]

I vote for scope creep.

There is NOTHING better than replacing everything (my car had $20+K of deferred maintenance) and knowing it is all good for another 20+ years, and running perfectly.

Again, I'm 100% happy to admit that although my car has been fairly meticulously maintained for the 20 years I've owned it, once I got into it I discovered two orders of magnitude higher levels of deferred maintenance than I thought I had.

I can GUARANTEE that all of you on this forum do, as well.

I know the @Jlaa is gumptioning up on his own Top-End Refresh. That deferred maintenance eats at you much more than a

 

[gerryvz]

@dionphaneuf
You know this is what you REALLY want....

Imagine this....

Being transformed into this.....

 

[nocfn]

Gerry you took your car to Scotty?

 

[gsxr]

Screamin' Scotty had about 30 seconds of useful content in that video (near the end, of course).

TLDR: If your engine is not direct-injected, use Top Tier gas and don't spend money on de-carbon treatments. (Or, you can watch him yell for ten minutes.) Engines without direct injection (like all Mercedes through at least the mid/late-2000's) will benefit from frequent Italian Tuneups.


What really annoys me about his channel are these bogus, completely fake, and totally inaccurate screencaps. Like the one shown below, on this video. That mangled cylinder head has ABSOLUTELY NOTHING TO DO with the video content (carbon deposits / cleaning). It's insane this guy has 2.2 billion views on YouTube and became a multi-millionaire screaming and waving his hands comically in front of a camera.

 

[maw1124]

I was just laughing with @dionphaneuf that I use the Allroad as the test case for BG’s decarbonization service (and some other vendor who may be out of business by now). It could be all smoke and mirrors but the amount of white smoke that pours out of the exhaust when they do it always shocks me, given the premium gas and Chevron Techron that car sees. But it also sees a bunch of short trips and consumes oil. I’ve done 2 in 15 years, so there’s that. I’m not incredulous that there could be some deposits in 7 years.

But I also might just be particularly gullible, which I can afford to be. I often remind people I can afford to be wrong — I don’t have to be right all the time. If you bat or shoot over .500 for your career in MLB or the NBA, you’re a hall of farmer.

maw

 

[nocfn]

I seafoamed my m117 and there was quite the show in the neighborhood LMAO! When the smoke cleared, there was plenty of cleaning that took place internally as the visible carbon buildup was no longer there. Power according to butt dyno was more responsive but I think the real effects was probably the shit-show in the cul-de-sac. I use premium gas and the PO of that car was not a car person, stopped using the dealer after the warranty and not sure there was a lot of things attended to. But if you want some excitement in the hood, definitely push some seafoam thru the intake, crank case pre-oil change and be sure you are up wind. LOL I have replaced just about everything on that engine, and she is going strong (no the pistons, crank and rings are still OE, as is the head gasket)

 

[maw1124]

Someone asked me which Seafoam I was using in the 55 earlier this week and I was like, “um… none.” I guess I’ll try it in the Allroad

maw

 

[gerryvz]

Additives of this sort, save for something like Techron for cleaning fuel systems, are wholly unnecessary and unneeded.

Perhaps Sta-Bil if you want to keep your gas fresh over the winter.

I cannot think of any other type of additive that would be needed for the M119, M120, M104, M117, M103, etc.

Sea-foaming one's engine is a redneck-y, "Benzworld" level activity. Very definitely beneath the level of discourse and maintenance activity here.

 

[nocfn]

I agree GVZ with the above. Snakeoils...... side note - not even Uncle Kent would approve of this..

 

[maw1124]

I guess that’s kinda why it hasn’t gone into anything. Well, nothing but the Audi, which doesn’t get run enough for hours at a time anymore. I’ll use Chevron, Redline, BG44k, the basics. But Seafoam, well, GVZ said it best.

But at the risk of repeating myself, if there’s a BG dealer near you to perform the decarbonization service, it’s worth the few bucks to decide for yourself, IMO.

maw

Additives of this sort, save for something like Techron for cleaning fuel systems, are wholly unnecessary and unneeded.

Perhaps Sta-Bil if you want to keep your gas fresh over the winter.

I cannot think of any other type of additive that would be needed for the M119, M120, M104, M117, M103, etc.

Sea-foaming ones engine is a redneck-y, Benzworld level activity. Very definitely beneath the level of discourse and maintenance activity here.

I agree GVZ with the above. Snakeoils...... side note - not even Uncle Kent would approve of this..

 

[gsxr]

For engines without direct injection, Italian Tuneups do wonders for removing carbon. Full throttle to redline is your friend, not your enemy. I think a lot of people believe full throttle at high RPM is somehow "bad" for the engine, and/or causes more wear. It doesn't. Wring your engine's neck as often as possible, and it will thank you. This is especially true for diesels, but also applies to petrol powerplants, including the M119.

 

[dionphaneuf]

I've used the Chevron fuel system cleaner when my fuel gauge gets all wobbly and its fixed it every time.

 

[gerryvz]

I have seen back in the day that some MB dealers offered BG-44 or whatever it is called as a "service" added-value package. That said, even though an MB dealer offers it, it is not needed. As the @gsxr says, an Italian tune-up -- and better yet just regular use at least once or twice a month -- is enough to keep the engine happy.

 

[gerryvz]

not even Uncle Kent would approve of this..

This is for the diesel guru @gsxr #OM61x

 

[Alphasud40]

I agree about the Italian tuneup. I do this ever day. I think a M119 at redline is one of the most pleasing sounds one can experience. Also aids in releasing tension like petting my dogs

 

[Alphasud40]

Screamin Scotty had about 30 seconds of useful content in that video (near the end, of course).

What really annoys me about his channel are these bogus, completely fake, and totally inaccurate screencaps. Like the one shown below, on this video. That mangled cylinder head has ABSOLUTELY NOTHING TO DO with the video content (carbon deposits / cleaning). Its insane this guy has 2.2 billion views on YouTube and became a multi-millionaire screaming and waving his hands comically in front of a camera.

Got to hand it to Scotty. He knows how to work the system to make a living selling his misinformation. I can’t stand to hear him talk. It’s a form of YouTube waterboarding.

 

[nocfn]

Coming back last week from the dealer who did my back glass, I got extended opportunities to hit triple digits on the speedo. Sure is effortless with the E500 - never gets old.