Butterfly
 

[QUOTE=razvy;2817475]What that "butterfly" do ? and who regulates it?
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The "butterfly" is a big flap that opens and closes, like a venetian blind and controls the amount of air that comes into the cylinder. If I remember correctly, yours is at the back of the engine, on the end of the air intake intake (outside of your filter housing). It's supposed to be in the closed position when the engine is cold, and open up when the engine warms up. If not attached, it will flop around, choking off your air when inappropriate, making the car jerk. It's a similar system to carburation butterflies at the top of carburators, attached to a choke selinoid. Look for the scoop coming from the filter housing, and look inside that scoop. Make sure it's hooked up to a connector wire/linkage, keeping it from flopping, follow the connections/linkages and make sure it's connected throughtout and not floppy. You can also try to block it open, as a test, and try driving it to see if the jerking continues when it's blocked open. If the problem goes away, you know that was the problem.

You might also want to get the car on a rack, put it in the affected gears, try turning the back wheels to find out if there's "flat spots" with harder turning, in which case, you're in for a tranny rebuild for new bearings. You can probably get a tranny shop to give you a free diagnosis. Also, what condition was the throwout bearing in, and the fork??? The other posters have given you directions on checking the rest of the drivetrain. Remember . . .isolate, and check and work your way through the entire system until you find the problem.

Also, a little known about possibility. Was the timing chain and all components replaced??? If it's the 2.2L engine, those engines were also used in reefers and had a different system setup. If the wrong one was used for R & R, it would cause that problem, but I would think it would happen in all the gears. Might be solved by replacing the timing chain with all components (correct one for auto use), or by adjusting the timing.

Go through the rest of the recommended checks first before delving into the timing, however. Which engine do you have??? the 2.2L or the 5-cylinder 2.5L, or the 6-cylinder?

OH, I forgot another thing: When the conversion to manual tranny was done, was the rear end replaced with it??? I believe the gear ratios are different for the the manual tranny version, in which case, that might be a problem.

Also, there is an engine shock in the front of the engine which IMHO is a real PITA to replace. Fairly cheap part, though. However, mine was flat for years and only cause rough idling.

I have the 2.5 5 cylinder , the fork is fine and throwout bearing is new whit pressure plate a new clutch ( under 500 miles) .
I am going to check on that butterfly in few minutes and I let you know what I found , I have a ? who controls the vacuum solenoid ?
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No this car was original 5 speed manual , but the engine was change from a automatic , I don't have the dampener road on the IP , I was look in for the bracket and deaden find it , the injection pump has a empty place to attached something .

What engine shock? at the belt tensioner ? That is been changed.

It wouldn't hurt too include the model MB in a signature so folks with faltering memories wouldn't have to go back to the beginning.:)

I 've seen this flap on the early W115, 240D engines, but didn't know the W190 engine used them.

The "spingie feeling" I sometimes get with my 85 feels like weak clutch disc springs. Good luck

190D
 

Yes, the 201 did have the butterfly. I discovered it when a mechanic and I tried to find out why my '84 190D, 2.2L, 5-spd was driving like a real dog after all the work completed - valve job, new clutch. The butterfly was one of those things not reconnected and we had to fashion a new linkage for it. Also, my non-working cruise control actuator never made it back into the engine compartment, which was fine by me, but had nothing to do with it's poor performance. However, I would try to totally disconnect yours, in case that is a problem. Sometimes, when I use it on my 300D, it will also cause that same jerking motion, even though I have an auto tranny.

You right Stevo , I well add to my signature .
I went outside and deed some checking :
The vacuum module in top the air filter is OK , i apply vacuum whit a mityvac and hold vacuum and operates the gate ( butterfly) .I remove the air filter and visually inspected and is OK.
I started the engine (outside temp 49º) and the module doesn't move , I check for vacuum and I don't have any ( zero) , I follow the lines and end up to a vacuum distribution vale in front of the battery ( passenger side) and i have vacuum going in but none going out on all the lines .

butterfly
 

so . .. warm up the engine and see if it opens up. If it does, it's working correctly. Or you can disconnect and freeze it in open position for test drive after it's warm. If the jerking goes away, you found your problem. If the problem is still there . . . hook it back up again and look for the next possible cause.

Yes, that is the engine shock I was referring to earlier. If it's new . . . obviously not the problem.

Right now it s in a open position , I am doing the test in a few minutes . I am curious to see if it get any vacuum , so far as I explain is dead .

I when for a test ,
Whit the vac. disconnected the butterfly is open( relax mode) and the car dose the same, then I apply vacuum whit a T and butterfly closed, I deaden notice a change in the engine sound or rmp , the car improve a little but the jerkin is still there .
Regarding that butterfly suppose to stay close during normal drive ?
The EGR valve can produce this symptoms ?

@Stevo
I added the car to my vehicles and deaden appear as my signature , where is that section ??
Thx

I had it too
 

After I did the 5spd conversion on my 190d it would exhibit the bucking behavior. I quickly learned to adjust my throttle foot to prevent this , not sure exactly what but it was 100% effective. I actually forgot about it until someone else drove the car. Cheers Dan

Not sure, the User CP, I would think

I am thinking the rear axle shafts , wear on the joints can produce this jerkin what you guys think ?>
Take a look at this video at min 3:00
Rear Axle Shaft Inspection & Repair on a Mercedes Benz by Kent Bergsma - YouTube

Did you every figure out the problem?

I have the same issue, part throttle, high load and its almost as if someone is engaging then disengaging the clutch over and over again causing it to oscillate back and forth getting worse and worse.

Letting off of the gas causes a considerable jerk, and getting back into it again does the same...

I was also wondering that, I think its the springs in the clutch disc getting weak. My 240D does the bucking thing under certain circumstances with about 50K on the clutch.