FIP Idle Adjusting Knob Is Max CCW

[gcw206]

I am a newer member, and have found this site very valuable when dealing with various SL "Issues". 
I have a 1969 280SL Automatic, that has a problem that I just recently discovered.  After shimming the Warm Running Device so it would completely close off when warm, I turned my attention to adjusting the idle.
Prior to any adjustments, the CO was at approximately 6-7% (it walked around a bit), and the idle was at about 900RPM.  I stopped the engine, and went to adjust the FIP, and discovered that the adjustment screw on the FIP was almost all the way out CCW. When I engaged the FIP adjuster, and moved it CCW, it would not disengage, and would slowly spin when the engine was running (while spinning, it would leak oil at the stem of the adjuster; when moved a bit CW it would disengage, and would not drip oil).  Since turning the FIP idle adjuster CW will richen the mixture, and centering the adjuster will require about 32 CW "clicks", will I get the mixture so far rich that the engine will never run again?  Or, should I remove the hex-sided threaded casing that houses the FIP adjuster, and see what is going on inside?  I assume that the PO decided to adjust the idle while the engine was running, engaged the adjuster, and the adjuster caught and spun to the total CCW setting.  The end of the adjuster may be damaged as well (it feels OK and seems to work OK when I move it CW, but I cannot be 100% sure).  Any ideas?  Thanks, Galen

[Benz Dr.]

It's possible to turn the adjusting screw out so much that it will stay engaged and it will turn with the engine. Try turning it in about six clicks, which is one complete turn, and see how it idles after that. If you find that you are still unable to lean out the idle mixture after turning the screw back again you could remove one thin shim from underneath the barometric compensator.  This will lean out the entire mixture across all of the ranges from idle to full throttle. Once you lean out the entire mixture you will have to turn the idle knob back in to enrich the idle mixture and you may need to adjust the warm up mixture as well. Removing a .010'' shim under the compensator won't change the mixture very much and it might be enough to do it. 

[Tyler S]

Galen, Also double check your injection pump linkage and make sure the pump lever is at its stop when at idle. It is possible someone lengthened the pump rod to compensate for a lean condition. (possibly caused by your warm running device not completely closing, which you fixed)  If this is the case you will have more "range" with your idle CO screw after the linkage is adjusted properly.

[catjim813]

Galen, my injection pump was running rich and adjustment screw was doing the exact same thing as yours.  Due to my pump running so rich and a constant oil leak, I chose to remove the pump and send off to calibrate and reseal.  I used a person in northern California called Fairchild Industries.  My pump was resealed and recalibrated for a very reasonable price. I am working through a fuel pump issue now but I feel the injection pump have been sorted out.  Tyler and Dr. Benz are giving you great advice.  If that does not work consider having some work done on your pump.

[Benz Dr.]

This is a general statement and I'm not directing my thoughts towards this thread or anyone in particular:

There are only a certain number of things you can do or check before you have to send out something to be rebuilt. Knowing what those things are, how far to look, and what your own resources are is the key thing here. Most of the info you need is contained within this site and if one knows where to look and what to look for it makes it easier. Understanding what you are reading and what to look for is key, and if you have the skills to do your own work, we are happy to help you. 

  I'm not one to discourage anyone from learning but I think it's fair to point out that you can easily end up costing yourself a lot more by making mistakes that happen from not being familiar with the work at hand. I know this because I've probably made every mistake that could be made during my early years but I did all of them while working on my own cars. To this day I still won't touch something I'm not familiar with and it's also why I won't work on anything newer than 1990 - too much electronics.

 I rely on experts all the time. Engine machining, starters, alternators, body work and painting, rad work,  chrome plating, tire changes, welding and fabricating, alignments and muffler work, upholstery, IP rebuilds, hydraulic repairs, electronic rebuilds, gauge rebuilds, and a host of smaller items. Although I do all of the work myself, I still have a lot of project management to do.

After you get your car sorted out the most important thing you can do is to maintain it and this site is very helpful in that regard. 


 


 

   

[gcw206]

Thanks to those who inserted their input, it was much appreciated.
Here is an update as to the FIP Idle Adjustment Problem:
It has been solved; The idle is now about 800 rpm, and the CO is at 4%.  Nice and smooth, no roughness, and good throttle response.
I went back and checked all of the linkage adjustments, rechecked the round shims on the WRD air slide, and changed the oval shims.  Then, I adjusted the idle adjustment on the FIP CW, then the air adjustment screw, and after a few attempts, it finally all came together.  The PO had made many adjustments that were not to specification, and as a result it ran very rich at idle.  In the past few weeks, I had to run down the entire list to finally resolve the issue, and I suspect that the rich condition was a combination of several factors:  Improper timing, non working distributor retard function, a leaky CSV, several bad injectors, blocked throttle body vacuum line, improperly adjusted constant speed solenoid, and probably THE biggest problem was the installation of a newer model heat feeler thermostat into the older model guide ring in the WRD (the feeler rode above the hole, not in the hole).  After several hours reading the posts on this site, a few dead ends, she now idles like a sewing machine.  Many thanks, Galen.

[Cees Klumper]

@ Galen: congratulations, you've done great, good to hear the information on this site was helpful

@ Dan: very well said!

[Tyler S]

Thats Awesome! And now you can say you have tackled and succeeded in repairing a Bosch MFI system!