300SEL 3.5, engine started after 2 years

[werminghausen]

I am happy, engine fired up after 2 years. I had adjusted engine/cam timing, new chain and off set keys, new cam lube plastic parts before and I kind a checked the breaker points, gap of 0.4mm, breakers are old.
Need to adjust throttle linkage but the butterfly flap is closing fine and Idles speed should be influenced by it?
The engine fired up and it ran on all cylinders but idle is poor. Idles speed is too low and engine was dying several times. I need proper idle speed in order to set the ignition timing with the light?
I need the expert's advice/directions on how to set the idle speed and set ignition timing right and idle speed. Which one is first? and how would you do it.
I have the inductive light and I have a laser speedometer to measure engine speed. Please help.

[GGR]

The butterfly should close completely. Idle air is adjusted by the big screw with a spring under it next to the cold air valve and the cold start injector (behind the dizzy when you face the engine).

For the rods, here are some lenghts that should help you adjusting:
- Regulating rod between rubber mount articulated on firewall and rod mounted between the engine and the firewall: 78mm;
- Regulating rod between rod mounted between the engine and the firewall and guide lever: 114mm on automatic transmission models.
- Then adjust the regulating rod actuating the butterfly in a way that the butterfly is completely closed and resting against its stop screw when stop pin on regulating lever is against idling speed position of intermediate lever.

First adjust idle with the big screw so that it is around 700 - 750 rpm, engine warm. Then check ignition timing. Should be 6 degrees ATDC.

[mercmad6.3]

I have found too,that the idle should be fast then the mixture at idle set with a CO meter,idle mix is adjusted on the ECU,in very small increments.
slow the idle to spec and readjust the CO meter again. This will ensure that you not leaning out the idle air mixture when opening the air bypass screw .
Give the engine a few hard revs to make sure that you aren't running on two year old fuel . That old fuel will make the engine idle badly .

if daylight can be seen through the throttle body when held up to the light,it needs replacing or a new shaft and butterfly.

[werminghausen]

Originally Posted by GGR

The butterfly should close completely. Idle air is adjusted by the big screw with a spring under it next to the cold air valve and the cold start injector (behind the dizzy when you face the engine).

For the rods, here are some lenghts that should help you adjusting:
- Regulating rod between rubber mount articulated on firewall and rod mounted between the engine and the firewall: 78mm;
- Regulating rod between rod mounted between the engine and the firewall and guide lever: 114mm on automatic transmission models.
- Then adjust the regulating rod actuating the butterfly in a way that the butterfly is completely closed and resting against its stop screw when stop pin on regulating lever is against idling speed position of intermediate lever.

First adjust idle with the big screw so that it is around 700 - 750 rpm, engine warm. Then check ignition timing. Should be 6 degrees ATDC.

Thanks GGR
I'll watch out for the big screw with spring,next to cold air valve and cold start injector...I don't know any of these components yet.
I have installed the airfilter but can take it off again if needed....well I guess if I want to adjust the throttle rods according your specs.
Butterfly flap is closing properly... i haven't tested the light behind, would need to take it off...shouldn't be too hard to do.
Questions:
1) Can i test idle speed without the airfilter in place? or only with it?
2) The big screw: do I adjust idle speed with this screw only?
Does this screw change COs 2 levels? You say 700- 750 rpm
3) after testing/adjusting ignition timing at 6 degrees after TDC: is there anything else I need to adjust?
4) How can I test Co2 level? I don't have any equipment.

Martin

[werminghausen]

Originally Posted by mercmad6.3

I have found too,that the idle should be fast then the mixture at idle set with a CO meter,idle mix is adjusted on the ECU,in very small increments.
slow the idle to spec and readjust the CO meter again. This will ensure that you not leaning out the idle air mixture when opening the air bypass screw .
Give the engine a few hard revs to make sure that you aren't running on two year old fuel . That old fuel will make the engine idle badly .

if daylight can be seen through the throttle body when held up to the light,it needs replacing or a new shaft and butterfly.

Thanks
I have no idea yet what the ECU is. Where is the ECU? Have never done the idle mix. Need to get a CO meter? Is this unavoidable to properly adjust the engine?
Air bypass screw is the big screw for idle speed adjustment?
Can I test the vacuum at idle in order to see if the butterfly is closing well?
There is a spot screw at the butterfly. Is this a factory setting?
Martin

[werminghausen]

[QUOTE=GGR;2585776]
For the rods, here are some lenghts that should help you adjusting:
- Regulating rod between rubber mount articulated on firewall and rod mounted between the engine and the firewall: 78mm;
- Regulating rod between rod mounted between the engine and the firewall and guide lever: 114mm on automatic transmission models.
- Then adjust the regulating rod actuating the butterfly in a way that the butterfly is completely closed and resting against its stop screw when stop pin on regulating lever is against idling speed position of intermediate lever.


So there are 3rods... I'll adjust the 2 ones coming from firewall ( 78mm and 114mm between center of ball joints).

Then I am not quite clear about the last rod #3 (butterfly rod) and how it is adjusted.
The stop screw for the butterfly for closed position: is this screw in need of adjustment or is this a fixed position and leave this alone?

The lever between rod 2 and 3 is rotating and also actuating the pressure control rod for the transmission (I guess for later up shifts at WOT). Is this the intermediate lever you are talking about?
This lever has a 'fork' piece for the control pressure rod.. Not sure how to adjust this one. I'll take some pics so you can see. Martin

[GGR]

Originally Posted by werminghausen

1) Can i test idle speed without the airfilter in place? or only with it?
2) The big screw: do I adjust idle speed with this screw only?
Does this screw change COs 2 levels? You say 700- 750 rpm
3) after testing/adjusting ignition timing at 6 degrees after TDC: is there anything else I need to adjust?
4) How can I test Co2 level? I don't have any equipment.

1) yes you can as long as you don't drop anything in the TB while engine is running... If Idle goes down with air filter on then your air filter is clogged.

2) and 4) Yes, you adjust idle speed with this screw only (air bypass screw as you call it). Yes, it changes CO level as adding more air leans the mixture and vice versa.. Co is adjusted at the ECU as Ron said. The ECU is located between the radiator and the right front fender. There is a rubber cover on it and you will find a "potentiometer" under that cover. Clockwise for enriching, ccw for leaning idle mixture. If you have no measure apparel turn it up to when the engine is idling fastest. Then reduce idle up to 700 rpm with the air screw and you should be fine.

At this stage it would be a good idea to measure the fuel pressure as it influences richness overall. Disconnect your cold start valve and plug a pressure gauge in there. Pressure with engine idling should be between 28 and 30 psi.

3) Yes, check the advance values at higher rpms as indicated in a previous post.

[GGR]

The stop screw for the butterfly for closed position: is this screw in need of adjustment or is this a fixed position and leave this alone?

Leave it alone if the butterfly closes completely. This is adjusted at the factory and should have a yellow paint dot on it.

The lever between rod 2 and 3 is rotating and also actuating the pressure control rod for the transmission (I guess for later up shifts at WOT). Is this the intermediate lever you are talking about?
This lever has a 'fork' piece for the control pressure rod.. Not sure how to adjust this one. I'll take some pics so you can see. Martin

Here I will let Ron answer as Auto transmissions are not my strong point.

[GGR]

Originally Posted by werminghausen

1) Can i test idle speed without the airfilter in place? or only with it?

I forgot about the air temperature sensor (ATS) in front of the air filter housing. While the housing can be off the TB, make sure the TPS is still connected. A dicconnected TPS richens the mixture so will put all your adjusments off once you reconnect it. A good test to see if the ATS is fine and the ECU responding well to it is to note idle speed variations when you plug/unplug it.

[Tomguy]

Originally Posted by werminghausen

Then I am not quite clear about the last rod #3 (butterfly rod) and how it is adjusted.
The stop screw for the butterfly for closed position: is this screw in need of adjustment or is this a fixed position and leave this alone?

Your kickdown rod comes up from the transmission. Basically, pop it off the nub. When the rod is off the nub it should be directly above it when the throttle is completely at rest. It should not be pulled at all.

The stop screw for the butterfly is properly adjusted easiest with the TB off the car. Make sure the butterfly closes completely but does not bind. It's a pretty close tolerance. You only would adjust it if you have a feeling it's off for some reason (like unknowing what kind of mechanic that knows nothing about EFI or D-Jet wrenched on it & thought it was an idle set screw).

[werminghausen]

Originally Posted by GGR

I forgot about the air temperature sensor (ATS) in front of the air filter housing. While the housing can be off the TB, make sure the TPS is still connected. A dicconnected TPS richens the mixture so will put all your adjusments off once you reconnect it. A good test to see if the ATS is fine and the ECU responding well to it is to note idle speed variations when you plug/unplug it.

I was trying out pulling the ATS plug and the idle speed went down very much (after I set idle speed and ignition timing) , almost stalling the engine. So I assume ATS is working?

[GGR]

Originally Posted by werminghausen

I was trying out pulling the ATS plug and the idle speed went down very much (after I set idle speed and ignition timing) , almost stalling the engine. So I assume ATS is working?

I would say yes.

[werminghausen]

Originally Posted by GGR

The butterfly should close completely. Idle air is adjusted by the big screw with a spring under it next to the cold air valve and the cold start injector (behind the dizzy when you face the engine).

For the rods, here are some lenghts that should help you adjusting:
- Regulating rod between rubber mount articulated on firewall and rod mounted between the engine and the firewall: 78mm;
- Regulating rod between rod mounted between the engine and the firewall and guide lever: 114mm on automatic transmission models.
- Then adjust the regulating rod actuating the butterfly in a way that the butterfly is completely closed and resting against its stop screw when stop pin on regulating lever is against idling speed position of intermediate lever.

First adjust idle with the big screw so that it is around 700 - 750 rpm, engine warm. Then check ignition timing. Should be 6 degrees ATDC.

I adjusted idle speed and ignition timing today. It was not too hard.
With the idle set screw, a tachometer and the light it was not too hard.
I could also watch what difference the vacuum pod did in changing ignition timing and change idle speed by changing timing.
I put idle speed at 800 rpm and adjusted the ignition timing at 6 degrees ATDC, adjusted speed severeal time...because with changing timing the speed is changing etc.
Then I was testing to pull the vacuum line and see what happens: It changed speed from 800 to about 850 rpm and ... timing when from 6 degrees ATDC to 5 degrees BTDC.
vacuum reading was 13" Hg, not sure what this means. Do you think this looks ok? I experienced that it took about 1/2 a minute until vacuum was built up again (13"Hg) does 13"Hg and the time it needs to build up sound like a vacuum leak at manifold?
I set idle to 730 rpm in the end. Martin

[werminghausen]

After adjusting idle speed and ignition timing (6 degrees ATDC only so far)
I was pretty ok with how the engine sounded and the throttle response was much better as before. However the adjustment on the distributor is at the edge ...meaning I had to turn the distributor CCW almost all the way to the stop to get the 6 degrees.
How does this sound?

[werminghausen]

Throttle adjustments:
I had removed again the airfilter housing. The adjusted the rod 2 to 114mm
I had a hard time to get rod 1 off the linkage..actually left it on...rod 1 is the
one at the firewall with the circle bent rod /the rubber disk in the middle and the one ball joint. It is hard to measure in place but this might be close to 78mm..the number you gave me.
I'll check this again and adjust if needed.
Then I'll try to do rod 3.
I guess that at WOT the kick down switch should be pressed and at the same time butterfly at the end stop?

Not sure about the transmission rod (for control pressure) attached to the center lever (3 ball joint lever).
If I disconnect it I have not much feeling for resistance. if i let it go the ball joint position is probably 1/4inch off compared to the ball head of the lever.
See attached pictures