W124 230te stalling/hesitating under load.

[Alx230te]

Also check the small sensor in the fresh air duct ...and -View attachment 152736

Chrck out the micro switch on the throttle leaverView attachment 152735

Throttle switch is closing circuit ok , no problems there .

Will be looking at the sensor plate next .

 

[Alx230te]

Not too familiar with this engine, does it have an inline fuel filter? Most engines do, has that been checked? The symptoms you describe sounds more like fuel starvation, more load, more fuel required but not getting through. Worth a look.

I replaced the main filter and that’s the only fuel filter is has except for the tiny one in the distributor that i took out as it was supposed to be taken out after it’s first service

 

[Bellow]

Is this sounding like an over fuelling issue?

Quickest way to find out is provoke the stumble and while it is stumbling turn the ignition off and put trans in neutral simultaneously. Pull one (or more) spark plugs and if sooty black - it's overfuelling.
If the plug(s) are wet with fuel either severely overfuelling (which I doubt) or ignition failings on the HT side.
HT weaknesses present under load and the fact that your problem is worse tipping into the throttle but can be circumvented by very slow throttle application is compatible with that. I know you've replaced HT parts but I haven't seen mention of something these engines are notorious for - damp in the distributor cap which when it evaporates with heat causes misfires. I think - but I'm not certain - that damp can enter the distributor via the crankcase which the lower section of the distributor has access to. Where the cap seals to the distributor body is the more obvious leak path for damp though.

 

[alabbasi]

I had this issue with an old 560SEC that I owned. It was related to the fuel distributor / EHA. I swapped both out with one from a junked car and the car ran fine.

 

[Alx230te]

I had this issue with an old 560SEC that I owned. It was related to the fuel distributor / EHA. I swapped both out with one from a junked car and the car ran fine.

I have a working spare and tried this , unfortunately it makes no difference.

 

[Alx230te]

Quickest way to find out is provoke the stumble and while it is stumbling turn the ignition off and put trans in neutral simultaneously. Pull one (or more) spark plugs and if sooty black - it's overfuelling.
If the plug(s) are wet with fuel either severely overfuelling (which I doubt) or ignition failings on the HT side.
HT weaknesses present under load and the fact that your problem is worse tipping into the throttle but can be circumvented by very slow throttle application is compatible with that. I know you've replaced HT parts but I haven't seen mention of something these engines are notorious for - damp in the distributor cap which when it evaporates with heat causes misfires. I think - but I'm not certain - that damp can enter the distributor via the crankcase which the lower section of the distributor has access to. Where the cap seals to the distributor body is the more obvious leak path for damp though.

So I last cleaned up the plugs in October and when I took them out today there was a bit of soot on the thread but nothing on the points . I cleaned them all up and took it for a quick run , then parked up in idle , with foot on brake dropping it between reverse and drive where it would kick and stumble but it wouldn’t stall . Checked the plugs and no signs of soot or fuel on them.

I checked my distributor cap and no damp in there or signs of damp . The cap and arm are only a few months old but the points were a little crusty already so cleaned them up .

Again all this happens after the car has warmed up , there’s never any of this running up to temperature.
Yesterday it did take 2 long turns of the key to get started but every other time is starts fine .

 

[Bellow]

then parked up in idle , with foot on brake dropping it between reverse and drive where it would kick and stumble but it wouldn’t stall . Checked the plugs and no signs of soot or fuel on them.

Any smell of fuel - on plugs or emanating from cylinders via plug holes? Fuel starved?
Stumbling is something I associate with rich mixture though. When lean, an engine tends to die sounding as if strangled - but a uniform sort of sound. Or, with backfires (through inlet or exhaust) - none of which you have reported.

I checked my distributor cap and no damp in there or signs of damp . The cap and arm are only a few months old but the points were a little crusty already so cleaned them up .

Damp here could be very difficult to identify as it is already mobile to cause a problem. Were it not for the faff of swapping all the HT leads from it, I'd suggest having a spare known to be dry cap at hand when it misbehaves and swapping it over to see if it clears the problem. Would the crusty contacts be a sign of corrosion caused by damp?
As an alternative to having to swap caps, does anyone know of a quick (roadside) method to blitz any damp out - or absorb it?

 

[BlackC55]

Double check for any air leaks. Under the metering head is a common area. Air leaks will cause poor fueling.

 

[Jobsworth]

Double check for any air leaks. Under the metering head is a common area. Air leaks will cause poor fueling.

Good advice. And the fat O rings that seal the injectors into their holes. You can use a spray brake cleaner to *carefully* check for air leaks. The engine revs will respond if brake cleaner is dragged in through a leak. The way you say it’s fine on the warm up cycle but then stumbles when hot suggests an air leak to me. Rich starting and warm up cycle tends to hide it.

 

[grober]

Can you swap the ignition coil from a donor car? or-- Do you have an EZL ignition unit?

 

[grober]

Only other thing I can think of is a faulty engine speed sensor-early cars took a signal from the dash rev counter? later ones from the flywheel sensor. dodgy ignition switch is another possibility corroded /bad connected engine earth strap?

 

[Alx230te]

Good advice. And the fat O rings that seal the injectors into their holes. You can use a spray brake cleaner to *carefully* check for air leaks. The engine revs will respond if brake cleaner is dragged in through a leak. The way you say it’s fine on the warm up cycle but then stumbles when hot suggests an air leak to me. Rich starting and warm up cycle tends to hide it.

I changed the injector holder seals this morning , definitely needed doing and double checking for other leaks . After replacing them the car took a good few turns to get going . Definitely ran smoother when I took it out for a quick drive but got back to the house and it is now worse than before .
It seems the more air leaks I fix (crank breathers changed too) the more it seems to run worse .

Here is a video changing through gears with fixed it on the brake.

Changing through gears foot on brake .

Watch "Changing through gears foot on brake . " on Streamable.

streamable.com

And one of the bay.

Engine bay

Watch "Engine bay " on Streamable.

streamable.com

Also again this morning the car took a few turns to get going but fine after that.

 

[Alx230te]

Also did the carb cleaner round any vacuum hoses/tubes and the manifold but didn’t change a thing .

 

[Bellow]

If it were mine.... if only to eliminate it as a possibility.... I'd have a look inside the distributor to check that the advance/retard mechanism is as it should be - without binding, broken springs, and that the vac capsule is doing what it should.

 

[neilrr]

If it were mine....I would have taken it to a good MB indy who knew these cars about £1500 back.

 

[ray_hennig]

look inside the distributor to check that the advance/retard mechanism is as it should be

I wouldn't think there would be any such timing components. I think timing will be handled by the EZL.

R

 

[optimusprime]

Dont forget the duty cycle ..

 

[Alx230te]

Today I took the whole fuel distributor/air flow plate off the car to do a clean up .
It’s was pretty filthy.

I gave it a really good clean out and put it back on the car . I also did a multimeter test on the potenometer and think this reading is off as from the YouTube videos it readings head past 5 when full depressing the plate and mine hits 2 then down to 1.

Potenometer reading

Watch "Potenometer reading " on Streamable.

streamable.com

Anyway It took a few turns to kick in but ran smooth .
Then my ABS light came on and instantly knew it was the alternator , got the multi meter out and was running at the battery at 8/9v .saw the leads at the alternator looks a bit fluffy , gave them a good wiggle and rev of the engine and boom , back to normal 13.7V
Could this be the problem with the car getting up to temperature and affecting the alternator and it’s connections ? It does have a squeaky bearing on start up .

Since that the car ran with the slightest kick ever now and again Uner load at standstill but drove absolutely fine and seemed to totally clear up. All good .

After that run I did have to take a couple of the fuel pipes off the top of the distributor as I missed a nut holding the distributor to the manifold. I put it all back together and started it up and it ran fine but the kicks came back under load at standstill in R or D. I took the car out for a run and it all cleared up . The car runs as it should . Spent ages in it after the run, in idle and under load at standstill but no more kicks or spluttering.

Sure is a weird one , I half think it could be blockage in the fuel pipes as it always ran better when I put injector cleaner through it.
Could it be alternator related? - I’m not so sure as I had all the lights and heaters on to check the draw but the car was fine.

Will see how it is later after cooling down and starting the warm up all again .

 

[Bellow]

Do you have a strobe light?

 

[Alx230te]

I can get an app for my phones led light , you thinking it’s a timing issue?