W124 230te stalling/hesitating under load.

[Alx230te]

Hi everyone,

My 230te (160k miles) has the bogging out/hesitation and stalling when pulling away from standstill when up to temperature.
There is no issue from cold start and the car drives fine . It’s once it gets to temp .

I’ve looked extensively on this issue and changed and checked many of the potential causes .
So far I’ve changed -
The distributor cap and arm
Ht leads
Fuel filter
Fuel injectors
Air filter
OVP relay
Spark plugs

What I’ve checked/done -
Fuel relay for dry solder -it’s fine
Checked fuel strainer - it’s clean
Checked the idle control valve - works fine
Removed the secondary fuel filter in the fuel distributor.
Checked both fuel pumps and cleaned up the terminals , they run fine .
Checked for vacuum leaks - all hoses intact and no cracks in rubber on the fuel distributor unit.
Drained the tank from from the fuel pump outlet (on rear ramps) to check for crap in the tank - was fine .

That’s what I’ve done so far and after all that the car will actually idle normally, which it didn’t do before . It used to hunt/stall once up to temperature and in idle .
On the motor way and above 1500/2k rpm it drives absolutely fine and on a long run (over an hour) the symptoms seem to clear up when you come to start stop traffic.
But the next day it will start playing up again. Runs fine from cold , once warmed up it can be hit or miss when you get to the lights or a junction- will pull away with a bit of hesitation then run fine in the higher revs, or it will kangaroo/want to stall till the revs finally kick in and run ok till next standstill .
It will idle ok , just under load it has the problems .

I’m really scratching my head with this one , can anyone here help with something I’ve missed ?



Cheers

 

[ray_hennig]

Spark plugs

Did you get the plugs from MB? I ask because many websites recommend resistor plugs. Some say that resistor plugs work OK but I see no reason to install anything but the correct plugs that you can still get from MB.

Which plugs did you install?

After ensuring that your HT system is 100%, I'd do a duty cycle check like this:

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You should probably see 70% at switch on, engine not running. Then 50% steady with the engine running before it gets to about 70C. Thereafter the duty cycle should oscillate around 50%. Say, from 45 to 55, or thereabouts. Other values indicate a fault or that the cowboys have been twiddling the screw at the top of the fuel distributor. Resist the temptation to twiddle unless you are 100% certain that all other sensors and settings are 100% correct. Can be time-consuming.

Do check the specific values for your engine. Those figures are for mine. And if you see, say, 30% instead of 70%, your meter's probes should be reversed.

And if you haven't got a duty cycle meter, I strongly recommend you get one. This diagnostic technique is invaluable with the KE Jetronic system. I bought a Fluke 17B+ and haven't regretted the expenditure. Not cheap but I did bin 2 or 3 cheapo ones before I paid the price and now enjoy the confidence. If you save a garage bill, you've paid for it.

Oh, and my usual rant: If you're serious about this car, get the entire HT system, from coil to plugs, from MB. The leads fit much better and it inspires confidence.

Another little tool that Ive used this weekend for detecting current drains is this:



Once I'd learned how to use if for low current detection - zeroing the meter - it confirmed that all is well. Again, confidence.

Good hunting.

RayH

 

[Alx230te]

Hi thanks for the reply ,

I bought the NGK non resistor plugs that people recommend on here and I have magnecore blue HT leads which are still in warranty.
I did a change back to resistor plugs just to see if there was a change but the symptoms stayed the same so put the non resistor back in.

I have got a multimeter but not sure if it will do a duty cycle ? See the picture attached.

Also I did a test in neutral at idle , if I accelerate as I normally would, it wants to stall , but if I gently and slowly accelerate it runs up to revs fine with no stalling at all.

So it feels like there’s a fuel/air mix issue?

 

[Alx230te]

Did you get the plugs from MB? I ask because many websites recommend resistor plugs. Some say that resistor plugs work OK but I see no reason to install anything but the correct plugs that you can still get from MB.

Which plugs did you install?

After ensuring that your HT system is 100%, I'd do a duty cycle check like this:

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

You should probably see 70% at switch on, engine not running. Then 50% steady with the engine running before it gets to about 70C. Thereafter the duty cycle should oscillate around 50%. Say, from 45 to 55, or thereabouts. Other values indicate a fault or that the cowboys have been twiddling the screw at the top of the fuel distributor. Resist the temptation to twiddle unless you are 100% certain that all other sensors and settings are 100% correct. Can be time-consuming.

Do check the specific values for your engine. Those figures are for mine. And if you see, say, 30% instead of 70%, your meter's probes should be reversed.

And if you haven't got a duty cycle meter, I strongly recommend you get one. This diagnostic technique is invaluable with the KE Jetronic system. I bought a Fluke 17B+ and haven't regretted the expenditure. Not cheap but I did bin 2 or 3 cheapo ones before I paid the price and now enjoy the confidence. If you save a garage bill, you've paid for it.

Oh, and my usual rant: If you're serious about this car, get the entire HT system, from coil to plugs, from MB. The leads fit much better and it inspires confidence.

Another little tool that Ive used this weekend for detecting current drains is this:

View attachment 152458

Once I'd learned how to use if for low current detection - zeroing the meter - it confirmed that all is well. Again, confidence.

Good hunting.

RayH

Just looked at the X11 port as stated in that video and I don’t have anything in hole 3. Even took the cover off and no cable .Probably as it’s the 230 and the video is a larger engine.

 

[ray_hennig]

Just looked at the X11 port as stated in that video and I don’t have anything in hole 3.

Oh dear. Strange. I would expect that port to be populated as is mine. What is your VIN? That will tell everyone exactly what you have.

R

 

[Alx230te]

Oh dear. Strange. I would expect that port to be populated as is mine. What is your VIN? That will tell everyone exactly what you have.

R

I should have the 2.3L M102 engine , always been that as far as I know .

 

[Alx230te]

I should have the 2.3L M102 engine , always been that as far as I know .

 

[optimusprime]

Is the sensor in the fresh air duck ok ? Also check the throttle linkage micro switch

 

[ray_hennig]

I should have the 2.3L M102 engine

Please post a picture of the fuel distributor.

R

 

[Alx230te]

Please post a picture of the fuel distributor.

R

I think I found a possible vacuum leak too
The hose as perished at the base .

 

[ray_hennig]

think I found a possible vacuum leak too
The hose as perished at the base .

Definitely eliminate ALL vacuum leaks.

And I think that my comments are irrelevant as you seem not to have an EHA on the fuel distributor - at least I cannot see it. This means that you might not have the Ke Jetronic but the K Jetronic.

I thought that all 124s would have the Ke but maybe not.

Comments from others????

I shall keep quiet unless someone comes up with more clues.

But you DO NOT want vacuum leaks.

R

 

[Alx230te]

Definitely got the eha valve as I had to replace it a year ago due to the original one leaking.

 

[Alx230te]

And yes definitely a leak in that hose too .

 

[Alx230te]

Just bought a breather pipe and this is where my one has perished

 

[ray_hennig]

And yes definitely a leak in that hose too .

Good progress. And you probably have other hoses, including the boot under the metering head that could be perished. And the ones around the idle control valve. In fact, everywhere, including down to the gearbox, assuming it's an automatic.

Keep us posted.

Still a bit baffled about the diagnostics port.

R

 

[Alx230te]

Good progress. And you probably have other hoses, including the boot under the metering head that could be perished. And the ones around the idle control valve. In fact, everywhere, including down to the gearbox, assuming it's an automatic.

Keep us posted.

Still a bit baffled about the diagnostics port.

R

Yeah I’m ordering full set parts from Germany , but got a second hand one on the way for Wednesday so hopefully that will help .
On a plus side the car has passed its MOT today , with only advisories to the tyres. So my emissions must be ok with the issue .

 

[Alx230te]

Good progress. And you probably have other hoses, including the boot under the metering head that could be perished. And the ones around the idle control valve. In fact, everywhere, including down to the gearbox, assuming it's an automatic.

Keep us posted.

Still a bit baffled about the diagnostics port.

R

So I got my be breather hoses and it’s made no difference, I’f anything a little more rough and my idle is now sat at 1k rpms .
Is this sounding like an over fuelling issue?

 

[optimusprime]

Chrck out the micro switch on the throttle leaver

 

[optimusprime]

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

 

[Benzowner]

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.