75 450SL won't idle

[AZreGuy]

Background - After getting the car I did the usual, even though the car was running fine, new plugs, wires, fuel filter, oil change, drained fuel tank and cleaned screen.
Car was running fine and I stopped to get something, left the car running and it started to spit and sputter, made a 2nd stop left it idle and it started to do the same. On the way home it stalled when I stopped for a traffic light. I got it started after a few tries and it ran the rest of the way home and stalled when I pulled it into the garage.
I tried starting it a few days later and it wouldn't, smelled like it was flooded. Let it sit for another day and it would not start again. I pulled all the wet plugs and let it sit over night. Re-gapped, reinstalled the next morning.
Tried starting without touching the accelerator and it would not start or even sounded like firing, after a few tries I put the pedal to the floor and it sounded like it was trying. I got it started and it spat and sputtered while i worked the accelerator. I took it on the road and ran it up to speed, it sounded good and ran fine until I stopped and it stalled. Stalled 3 or 4 times while I put it in the garage.
If I kept the RPM's up I could keep it going but as soon as idle drops it stalls.
Where to start?

[RadioTek]

I'd suspect the cold start injector is frozen "open", since it sounds like you're flooding out, if I read your description correctly.

Also, check your dwell, if you still have the breaker points under the distributor cap, I had a lot of problems until I changed out to a Cane/S&S unit to get rid of my points.

Just a couple of wild guesses.
Scott

[AZreGuy]

Could I disconnect the power wires to the cold start injector to rule out that as a cause of the excessive fuel on the plugs? Is it required to run or truly for starting?

[Walrus]

Originally Posted by AZreGuy

Could I disconnect the power wires to the cold start injector to rule out that as a cause of the excessive fuel on the plugs? Is it required to run or truly for starting?

you can disconnect, but what is that really gonna tell you? better to check fuel pressures (system and control), mixture, and cs injector leakage...

[AZreGuy]

Just want to know if it is stuck "open" and flooding the engine

[Walrus]

Originally Posted by AZreGuy

Just want to know if it is stuck "open" and flooding the engine

I guess what I was trying to say i, how is pulling the plug gonna tell you the condition of the CS Injector? lets say you pull the electrical connector, and still have the problem. Does that really tell you the valve is stuck open? It is truly only for starting, and is on only a few moments. If you want to check it, remove the injector and stick it in a bottle, still hooked up to fuel. Then jump the fuel pump relay and see if it leaks... You "could" remove it, leave it hooked to the fuel line, pull the plug and have someone try and start the engine as you watch the injector. All care exercised, because there is a potential for atomized (highly flammable) fuel...

[RadioTek]

Have you checked your points dwell angle? I had a similar trouble once when my dwell had gone to too high a setting.

Scott

[AZreGuy]

did not check dwell, have to go get a new meter for that.
It started right up today and ran well down the road but when idle went down it stalled, it started right up but had trouble keeping it running when I tried to get it in the driveway. I will pull the plugs and see if it is completely flooded or not.
I disconnected the power to the CSV but that did not help so Walrus you are right, I still do not know if it stuck or not

[AZreGuy]

I got a dwell meter.
I checked the points gap and it looked closed when on high lobe, so I adjusted it to .014.
I started the car and the dwell was reading around 23. what do I need to do or adjust to get it around 32?
The car has actually been idiling for about 5 minutes and sounds good.

I have a blue bosch coil and hooked up meter to the leads of it, I found no placed to hook it to the green wire coming from the condenser, that seem to go to the box on the fire wall with no oping to clip to.
When I pulled the connector part of it desinigrated in my hand as well as the other one there.

[AZreGuy]

And then when I went to take it for a test drive it stalled and will not idle!

[RadioTek]

Originally Posted by AZreGuy

I got a dwell meter.
I checked the points gap and it looked closed when on high lobe, so I adjusted it to .014.
I started the car and the dwell was reading around 23. what do I need to do or adjust to get it around 32?
The car has actually been idiling for about 5 minutes and sounds good.

I have a blue bosch coil and hooked up meter to the leads of it, I found no placed to hook it to the green wire coming from the condenser, that seem to go to the box on the fire wall with no oping to clip to.
When I pulled the connector part of it desinigrated in my hand as well as the other one there.

When you look at the points, there should be a small notch in the base end opposite from the pivot post. There should be two little nubs near that notch. You should be able to place a flathead screwdriver in the notch and between the nubs. That is how the adjustment is supposed to be mad: Back the hold-down screw off a little, tweak the adjustment, reassemble, and retest. Sort of a "trial and error" procedure, until you get to the approx 32 degree desired setting. Now do you see why so many people go to aftermarket electronic replacements?

Another thing to check is the actual coondition of the green wire itself. Mine had a few cracks in the insulation where everything was being done by one or two strands of the wire. If it's in the way or damaged, you can remove the condenser. It really isn't necessary at the low voltage used for switching in this particular application.

Bosch uses the points as a switch to turn a transistor on and off to drive the coil, that's what the box is behind the drivers' headlight. Less voltage and current at the points, less arcing to shorten the life of the contacts.

Also, clean the contacts themselves, just for insurance sake. Just run a piece of coarse paper through them a few times to polish up the surface. Nothing abrasive, just a business card or heavy bond paper.

Where in the Valley do you llive? I'm in North Glendale We might be able to get together one of these days if you need another set of hands sometime. PM me if you can, I have a weird work schedule, but we mught be able to meet up.

Scott

[AZreGuy]

got dwell set to 34 but points gap opened to .024. The car is idling at 1300 -1400 it sounds like it want to kick down but doesn't. Is there a way to drop idle or is that electronically controlled?

[RadioTek]

Ok, you've got the dwell set pretty good. The idle is adjusted with a large flathead screw that is facing up just behind and to the right of the disributor. There are a coulpe of black hoses that come from under the air cleaner to a couple of devices. One has the large screw on it, and that is what you use to adjust the idle.

This picture will give you an idea of where to look, but the idle valve the bubble is pointing to is the "fast Idle valve" Auxiliary air Valve. The actual Idle speed control valve is just to the right of it, with the screw under the bubble label.

The photo is taken from here: Components Locations Acronyms Pics - Page 2 - Benzworld.org - Mercedes-Benz Discussion Forum

which is in here: The Encyclopaedia Germanica Volume 107 (aka EGv107) - Benzworld.org - Mercedes-Benz Discussion Forum

That is another forum that you should probably check out. It's a bit more active than this one, and there's a sort of library (the second URL) that has a LOTof information.

Scott

[AZreGuy]

I found the big screw and turned it in 1 turn, that brought idle to about 1000, it drops to 800 when in D. There is only a 1/2 turn from it being closed now though.
I drove it and it ran fine, it stayed idling even after I brought it home.

The spark plug wires on the passenger side seem pretty hot to the touch though. I never touched them when running before so I do not know if this is a new issue.

[Graham]

What type of plugs and wires did you install?

Do you still have cat converters in engine compartment?

Read everything in that "other" forum link. It's a good start.

Usual places to start are AAV sticking, trigger points worn or oil coated, timing (set it to 25-30 BTDC), fuel pressure - set to 30psig min, but preferable a little higher. Lots more but first learn as much as you can about the D-Jetronic fuel injection system.