disconnecting MAF and no difference in idle ..

[Ertech]

Hi guys
engine is running rough this morning , I changed caps and tested each wire with a timing gun to see if they fire well.
When I disconnect the MAF nothing happens ,ifdle does not change . does this mean the MAF is bad?
thanks

 

[maw1124]

Yes.

maw

 

[nocfn]

Ok MAW, no codes on live data, at full temp, 2500 RPM, mash to 3000 doing generous speeds and audible burps and farts. wires caps rotors plugs fuel pumps and filter all replaced during process. A Cat-less Flieben exhaust from headers to tail. Is it the MAF?

 

[gsxr]

engine is running rough this morning , I changed caps and tested each wire with a timing gun to see if they fire well.
When I disconnect the MAF nothing happens, idle does not change . does this mean the MAF is bad?

Best diagnosis for the MAF is to view live data and compare to the values in this thread. The typical failure mode for the MAF is where it's totally dead, reading a fixed number for airflow at all times (never varies). With a dead MAF, the CEL will illuminate if the car has a working CEL.

If the engine is running rough and does not change with the MAF either connected or disconnected... the MAF may be ok. If the MAF was bad, there should be some difference one way or the other.

Does the car drive normally and only have a rough idle?

 

[maw1124]

Ok MAW, no codes on live data, at full temp, 2500 RPM, mash to 3000 doing generous speeds and audible burps and farts. wires caps rotors plugs fuel pumps and filter all replaced during process. A Cat-less Flieben exhaust from headers to tail. Is it the MAF?

Point taken.

But on my car, if I disconnect the MAF and nothing changes, the MAF is bad until proven differently.

So as a first start my answer remains.

maw

 

[gsxr]

But on my car, if I disconnect the MAF and nothing changes, the MAF is bad until proven differently.

I've never actually tried this. When I have a chance I'll see what happens on an engine running normally with a good MAF.

 

[jhodg5ck]

Oddly enough we still haven't had a bad MAF come through the shop... Haven't played the disconnect when running gig, but I to am curious as this point!

 

[maw1124]

@nocfn and I are discussing his case too. On some of these "warm car stumbles" I often suspect FPR before almost everything else. But it takes someone testing the fuel pressure at the rail while the car is having troubles -- a two person diagnosis most of the time. Back when my LH was having trouble, my Jono Klink Edd China mechanic (aka Rex) focused on the FPR first, which I thought was interesting and I never forgot it. Only when the FPR was fine did he focus on the computers.

maw

FWIW... on that occasion I walked into the shop suspecting LH module based upon researching this Board, but he ignored me ("us") until he ruled out FPR.

 

[Ertech]

Let the fun begin lol.

checked the caps for humidity , one of the caps had the terminals very thin so I replaced those . I did not remove the insulators since 5 out of 6 rotors bolts were rounded .I put my timing gun on each of the wires including the two lead ones and the timing light patterns looks good , no visible miss.
Gove the car for 100 miles and rough idles was still there . on highway car runs good.
I toke the MAF off since I have a spare and the rubber junction disintegrated . I should be getting a replacement tomorrow
This is what I did so far.
I guess my first step is to put the MAF back and look at the reedings . I have a c3 will check live data for MAF .
I will report back.
thanks guys as always .

 

[Alphasud40]

From my experience and diagnosis over the years a quick and dirty way to diagnose the MAF was to unplug the MAF and check throttle response with it unplugged. The manufacturer has good failsafe tables built into the ECU which will provide surprisingly good drivability without the sensor. You can grab your oscilloscope and VE tables but in the flat rate world time is king. Then I would try and clean the sensor and reevaluate. Sometimes it worked but when it didn’t I would replace with OE and test drive without clearing the adaptions. Nothing more satisfying then watching the fuel trims come back into line.

 

[Ertech]

little update while waiting for the parts.
manage to take the rotors of and one of the insulators is cracked .

 

[emerydc8]

 

[Jlaa]

Ok MAW, no codes on live data, at full temp, 2500 RPM, mash to 3000 doing generous speeds and audible burps and farts. wires caps rotors plugs fuel pumps and filter all replaced during process. A Cat-less Flieben exhaust from headers to tail. Is it the MAF?

@nocfn and I are discussing his case too. On some of these "warm car stumbles" I often suspect FPR before almost everything else. But it takes someone testing the fuel pressure at the rail while the car is having troubles -- a two person diagnosis most of the time. Back when my LH was having trouble, my Jono Klink Edd China mechanic (aka Rex) focused on the FPR first, which I thought was interesting and I never forgot it. Only when the FPR was fine did he focus on the computers.

maw

@nocfn , in your case, without spending time/effort/money in replacing yet more parts, is it possible to verify that fuel delivery is consistent? Yes, the fuel filter and pump have been replaced but what if the pump is working sporadically (which could be capacitors in the LH). Or, what if the fuel press regulator needs replacing as @maw1124 states? It is possible as well that fuel delivery is INTERMITTENTLY inconsistent which might make things harder to diagnose.

Also .... what are the long term fuel trim values like from Star / SDS? Just curious.....

 

[gsxr]

How-To thread for checking fuel pressure linked below.

See post #14 for the setup I use to check pressure while driving. The gauge+hose is not cheap, but it will positively eliminate fuel pressure as the potential culprit when chasing intermittent issues like this. You drive until the problem occurs (power loss, burpfart, whatever) and see if the fuel pressure is normal or not. This setup positively identified intermittently failing fuel pumps on at least 2 of my cars, and also positively identified fuel pressure was not the problem on another car...

HOW-TO: Checking M119 & M104 fuel pressure | "HOW-TO" Tutorial Articles

GSXR edit: Click here for "How to" on replacing FPR. For diagnosing issues with the M119 such as difficult cold and hot starts, it's important to be able to check the fuel pressure. This gives an idea as to the pressure at the injectors during various running conditions of the engine. It can...

www.500eboard.co

 

[maw1124]

@gsxr, while we're on this topic, how much does the fuel sender in the tank have to do with this?

I've been edumecated that I shouldn't store the cars on E because the empty tank full of air allows corrosion to set in on the fuel sender, while leaving it immersed in the cleaning agents and emollients of gasoline does not. I'm wondering if storing the car on E didn't contribute to @nocfn issues, as it seems they *might* (fingers crossed) be clearing up now that he's running a full tank of gas through again.

I've also been counseled to "just run a few tanks through and see if it clears up on its own" before putting in a new fuel sender when I had that problem.

Any thoughts?

maw

 

[gsxr]

@gsxr, while we're on this topic, how much does the fuel sender in the tank have to do with this?

On the 124, the level sender in the tank only connects to the gauge in the cluster - no connection to the rest of the fuel system. Later chassis (particularly 211 and newer) are a different story as those have the pump inside the tank.

I've been edumecated that I shouldn't store the cars on E because the empty tank full of air allows corrosion to set in on the fuel sender, while leaving it immersed in the cleaning agents and emollients of gasoline does not. I'm wondering if storing the car on E didn't contribute to @nocfn issues, as it seems they *might* (fingers crossed) be clearing up now that he's running a full tank of gas through again.

For storage of less than a year, a full tank is probably a good idea, along with some StaBil fuel stabilizer. However for really long term storage (2-3 years or longer, without driving enough to burn through tank contents)... I'd seriously consider having the tank near empty. Disposing of 20+ gallons of bad gas is not fun. The 124 has a "sealed" gas tank which does pretty well keeping gas from evaporating. Newer chassis (as of 210) are different and the tank contents can evaporate over several years.

I've also been counseled to "just run a few tanks through and see if it clears up on its own" before putting in a new fuel sender when I had that problem.

If you know the fuel in the tank is old or questionable, burn through it deep into reserve (or, drain and use in your lawnmower). Then refill with fresh TopTier gas along with a bottle of Red Line SI-1 cleaner and see if the issues improve. The sending unit can be opened up and cleaned if needed, while it's out you can shine a flashlight inside the tank and look for signs of corrosion. This is more of a concern in high humidity areas IMO.

 

[maw1124]

On the 124, the level sender in the tank only connects to the gauge in the cluster - no connection to the rest of the fuel system. Later chassis (particularly 211 and newer) are a different story as those have the pump inside the tank.

THIS was what I needed clarified. Thanks @gsxr. I have a mix of pump inside the tank and not.

As for remedy, in FL I just make sure the cars get driven and topped off with fresh new gas when done. They never sit more than a year.

Cheers,

maw

 

[Ertech]

hi guys a little update.

1-tested the MAF's I have and both according to Dave's data show ok .
2-changes the insulators , cap and rotors tested firing with my test light on every lead and ok.
3-tested fuel pressure regulator etc and ok as per Dave's link .

car is has slight idle hunting then goes perfect for 1/2 sec then goes back.
I ordered the correct F8DC4 plugs < dont know what it has now .

what else can I try? no codes stored .
should the idle be around 900 in park ?
When Input in drive it goes down to around 6/700
thanks guys let the fun begin .

 

[gsxr]

Idle RPM should be about 650-700rpm in Park, about 550rpm in gear, at full operating temp (80C+).

What are the problems / symptoms? Is it only a rough idle, but otherwise drives normally with good power etc?

 

[Ertech]

Idle high in park
Good power but a miss before full power comes on
I feel a miss especially in drive and stopped slight engine shake

 

[gsxr]

Check for vacuum leaks. Do a smoke test on the intake manifold if at all possible...

 

[Ertech]

Just did a smoke test got a leak at the disc looking thing

 

[gsxr]

That's the EGR valve. No other leaks? Hmmm. Also make sure the purge valve ("MOT" valve) by the EZL is not stuck open, this will cause a large vacuum leak that otherwise goes unnoticed.

 

[Ertech]

The plastic vacuum lines are so brittle they kept on braking all the way down to the air pump. I replaced the line going to the egr and the rubber connector close to the air pump broke it’s like a round rubber with a fitting connecting to the blue vacuum line .
What is this and can it be replaced ?
Thanks

 

[gsxr]

That's the air valve for the smog pump. It should just use a small section of standard rubber vacuum hose to connect the plastic tubing to the valve. Nothing special. Sounds like you may need to replace ALL the vacuum tubing in the engine compartment, that has not already been replaced. It's cheap, at least the generic non-color-coded tubing is cheap.

 

[gerryvz]

You can check my Top End Refresh thread in the Project Journals sub-forum for HOW-TOs on all of that vacuum line replacement, including the branch off to the smog pump, EGR valve, etc.

My vac lines were all Uber brittle and had been causing a nasty & persistent CEL for years (relating to air injection — smog pump).

 

[Ertech]

Gery and Dave, I read the top end rebuilt and your air valve from the smog pump looks different than mine , from the little I can see it looks like a rubber hat with a rubber nipple protruding?is this possible ? see my picture above taken with a Mirror .it probably the rubber left over where it broke . will report back tomorrow
there are 3 different part numbers for the vacuum like , they are all the same size? only color changes?
thanks

 

[gsxr]

Nah, you just aren't getting a good view of it. The valve is metal, the vacuum port is metal, with a rubber hose that broke off. Remove the remnant of the old hose and it might start making more sense.

Mercedes used different color/stripe tubing in the engine compartment. Some might still be available but several of the originals are NLA. You can use plain clear/white tubing, just don't get the mixed up. Apply some colored tape to help identify them.

 

[gsxr]

Tubing list here:

List of part numbers for Tecalan vacuum tube & fittings | M119 Engine

From my archives. Please note that some of these may be NLA (No Longer Available) and superceded to a different part number. Price is roughly $5-$7 per meter of tubing, MB MSRP. Vacuum line ("plastic" Tecalan pipe, 4mm OD, 1mm ID) ================================================== ===...

www.500eboard.co

 

[Ertech]

Could not wait till tomorow sounds familiar,
Was able to reconnect the vacuum at pump.

1- tested all the leads with my timing light and got a good pattern of flashes , can I rule out ignition related since idle goes up not down ?ordered new correct plugs since I don’t know how old they are
2 -tested fuel , MAF
3- did a smoke test and had a very little smoke from egr vale or base of it .
Tomorow will swap Egas then LH modules one by one .
4- I forgot to check the MOT valve , if stuck opened the vacuum will go to the gas tank?should this cause a CEL if stuck opened?
Can I pinch the hose to simulate closed ?
5- from what I read if this was ETA related I would got a CEL??

 

[gsxr]

4- I forgot to check the MOT valve , if stuck opened the vacuum will go to the gas tank?should this cause a CEL if stuck opened?

If stuck open, vacuum will go to the carbon canister, not to the gas tank. The canister is vented to atmosphere, so this ends up causing a significant vacuum leak.

Can I pinch the hose to simulate closed ?

Disconnect the 8mm hose/tube at one side of the valve, and plug both ends, to seal off / separate the engine.

5- from what I read if this was ETA related I would got a CEL??

Not likely to get a CEL. The CEL only illuminates for emissions-related faults. It doesn't care about anything else. But, the ETA (or E-GAS) is a potential cause since those 2 components control idle RPM. Odd there would be no fault codes though. How old is the ETA? Ever rebuilt?

 

[gsxr]

Idle high in park

Most likely vacuum leak, or an issue with ETA or E-GAS. Also make sure the NSS signals are correct, view live data while moving the gearshift through each position.

Good power but a miss before full power comes on

Is this at part throttle, full throttle, or both? Will it pull cleanly to redline or not? A 'miss' implies ignition misfire, do you mean a hesitation in power delivery? They are not the same thing.

I feel a miss especially in drive and stopped slight engine shake

How old are the engine mounts?

 

[Ertech]

I have a spare good egas LH and eta. my Eta is original I think. upper and lower wiring is 3 y old
engine mount less than 2 years , problem is part throttle , full throttle to redline good

 

[gerryvz]

Still sounding to me like it is an ignition-related issue, in terms of the miss.

Your mirror photo above is of the smog pump with rubber broken off on the nipple.

For the EGR valve, you may be able to just replace the gasket at the base, and see if that solves the problem. That is, if the EGR valve is not stuck internally.

Honestly, I would strongly consider just replacing all of the soft bits at the intake manifold and the top end of the engine. That would include all vacuum lines, gaskets, rubber nipples and connectors, black rubber air hoses atop the manifold, Tecalan tube that goes off the ETA, ETA gasket, EGR gasket, ETA rubber boot, rubber smog pump hoses, possibly the rubber donuts that mate the halves of the intake together.....the whole works. You won't regret it and it's a job that could be done in a day, or over a weekend.

 

[maw1124]

Honestly, I would strongly consider just replacing all of the soft bits at the intake manifold and the top end of the engine. That would include all vacuum lines, gaskets, rubber nipples and connectors, black rubber air hoses atop the manifold, Tecalan tube that goes off the ETA, ETA gasket, EGR gasket, ETA rubber boot, rubber smog pump hoses, possibly the rubber donuts that mate the halves of the intake together.....the whole works. You won't regret it and it's a job that could be done in a day, or over a weekend.

At 30yrs, with a hunting and surging idle, given how hot these engines run and how tight is the engine bay, THIS seems the best advice. Otherwise I fear you'll be hunting vacuum leaks literally forever. If some of the tubes are brittle, it's pretty safe to assume they're all brittle.

maw

 

[Ertech]

a little update .
put a used egas in and the idle went down to where it should be so I guess that module was also bad
the purge valve was also stuck opened , so I put a used tested one from another benz I have but the the connector is not the same and to small to put any clip there .I will have to go to the electronic store tomorrow .
1-can this affect my bad running engine having the plug to purge valve disconnected?
2- I Get this recurring code on LH module its a curent fault not stored one .
3- did a long smoke test and no leak
4-when I shut the engine and re start It will rend well for a few seconds and sometimes it runs well for a couple of seconds . when I hit the gas it sputters but goes hard .
5- I feel it’s not running on all cylinders
If I get a timing light pulse on each wire does that meet the distributor is sending electricity or the spark plug igniting
Can I get a pulse even if the plug does not fire ?

 

[gsxr]

You can drive with the purge valve disconnected - block off the pipes. All that will happen is fuel tank vapors get vented to the atmosphere, instead of being burned. Leave the electrical connector attached to the purge valve to avoid a fault code.

If you keep getting the cam timing actuator fault after clearing... make sure both are connected! If your upper engine harness is original, replace it.

For the ignition system, view live data on the EZL with the engine running. Ideally, do this when it's not running on all cylinders, or otherwise not running correctly. Indicated voltage should be in the low 30's on all cylinders. If any spikes up to 60-70v intermittently, that indicates a misfire on the specific cylinder. If all voltages are even (probably low/mid 30's) and the engine is still not running smoothly, something else might be the cause...

 

[Ertech]

upper and lower harness is new of 2 years , cams are connected , it shows a curent code but not stored code . will see the live data on the EZL.

my timing light days are foggy .If I get a timing light pulse on each wire does that meet the distributor is sending electricity or the spark plug igniting ?
Can I get a pulse even if the plug does not fire ?

 

[gsxr]

upper and lower harness is new of 2 years , cams are connected , it shows a curent code but not stored code . will see the live data on the EZL.

EZL live data will positively confirm if there is a misfire or not, AND will show you the specific cylinders misfiring.

my timing light days are foggy .If I get a timing light pulse on each wire does that meet the distributor is sending electricity or the spark plug igniting ?
Can I get a pulse even if the plug does not fire ?

This tells you that a spark was sent through that wire, but you cannot tell if the plug is firing. If the spark is shorting out somewhere else you'd still see a pulse but there would be a misfire in the cylinder. I have never used my timing light on an M119...

 

[Ertech]

Dave you are a genius .
spark plug boot and spark lug FULL of oil .sorry for wasting your time. should I checked this first .I guess valve cover gaskets . here are before and after cleaning screen shot . cleaned please plug and now perfect.
but this morning when I started the car got a air light and limp mode , if I re start it goes away.this happens once a month . got the cam codes again < I had
cleared memory>.
can this be related ?
What make valve cover gasket victor ,elating or goetz?

 

[gsxr]

Yikes! That isn't good. If you don't fix the source of the oil, it may happen again. Check/replace the valve cover gaskets, use OE/Genuine gasket kits only. Good time to inspect the chain rails while the covers are off.

ASR light & limp mode are completely separate issues, unrelated. Ditto for the cam solenoid codes. If you have limp mode there should be fault codes on the E-GAS module and maybe ASR also. If the upper harness is good and cam solenoids are connected properly, try swapping in a different LH module for grins.

 

[Ertech]

do cam solenoids go bad?
every time I got the ASR light in the morning its in limp node until I restart.
how long do the codes stay in memory ? I will scan tomorrow

 

[gerryvz]

Cam solenoids don't typically fail from a mechanical standpoint. Usually they leak oil, which is the most common reason they are replaced.

 

[gsxr]

do cam solenoids go bad?

As Gerry said, they almost never fail. And, you'd never see both fail simultaneously. They often leak oil though, which should be remedied as it can cause misfires from oil soaking the lower edge of the distributor cap.

every time I got the ASR light in the morning its in limp node until I restart.

Since your ETA is original... probably time to rebuild/replace it. What fault codes are on the E-GAS module after you get limp mode?

how long do the codes stay in memory ? I will scan tomorrow

Most codes remain in memory permanently until you clear them. This is why you can get "code diarrhea" if they have not been checked/cleared in a very long time, like 10+ years...

 

[Ertech]

a little update .
waiting for spark plugs , just for giggles I swapped plug 3 to 2 and the problem went to 2 cylinder , glad that is sorted out.
1-As for the asr light and limp sometimes in the morning got code in EFP module 051 idle speed safety contact m16/1s2??
2- I still get the cam codes with 3 different LH modules .also if I try to activate cam 1 or 2 it says fuction aborted .
if I put a 12v battery to the magnet I hear it click , I also tried a spare I have , the code is stored current faults what are your thoughts?
thanks guys

 

[gsxr]

1-As for the asr light and limp sometimes in the morning got code in EFP module 051 idle speed safety contact m16/1s2??

That is an internal switch inside the ETA. Time to send it to Victor for a rebuild, or gamble on a used one...

2- I still get the cam codes with 3 different LH modules .also if I try to activate cam 1 or 2 it says fuction aborted .
if I put a 12v battery to the magnet I hear it click , I also tried a spare I have , the code is stored current faults what are your thoughts?

Seems like there is a wiring issue between the LH module and the cam solenoids. You'll need to trace the wires between those two points and figure out what's going on. Use the docs linked below.

https://www.w124performance.com/docs/mb/M119/M119_LH_pinouts.pdf

https://www.w124performance.com/docs/mb/M119/M119_LH_schematic1.pdf

 

[Ertech]

Thanks Dave you got all the answers.
I checked the wiring pin 22 right and 41 left of the LH socket engine side and all way to the plug at the magnets perfect the prongs are closed
And ground on the other red green wires and also ok.
Maybe it’s a problem with my Chinese scanner ?
Can I test cams while driving ? I don’t see a difference driving with or without them

 

[Ertech]

Ok found the problem on the cam adjusters
I had a fuse of the dm module ( the 1st by firewall ) burnt
Replaced it and now all ok

 

[Alphasud40]

That’s awesome. Looks like you just about have it licked.

 

[gsxr]

Oh wow! That is really odd. I did not know that if 1 fuse was blown on the BM/GM, the car would still run normally, but not have cam advance function. I don't see that in the schematics either. SO bizarre.

Is the car running much better now? Without the cam solenoids working, the midrange power (2000-4000rpm) would be noticeably weak.