Bob,

Sorry - what's a TOCR? I looked at the diagram and #28 looked like a connector for the fuel line to the WUR.

My 1975 CIS system is very simple - but I think that they are not all the same. I have a hand throttle - so no AAR or AAV. I have a WUR, a decel valve, and a cold start injector. No other CIS controls - it's pretty simple.

Explain your inability to increase the idle above 500 RPM. Is that with the idle air bleed screw all the way out? If so, that could be an indication of a rich idle.

An idle that hunts up and down (you say lopping) could be an indication of a vacuum leak.

If the car has been sitting, I would clean the fuel system (drain the tank), new fuel filter, look for vacuum leaks, and check that the advance weights in the distributor are not gummed up - and a good tune up is always a good idea.

Let us know how you are getting along - you have some really good help and suggestions on this thread already.

Rex

Item 28 appears to be a fuel line adapter fitting on the WUR; are you saying the system is missing the WUR (item 27)?

Sorry for the confusion...It's the Throttle Operated Control Pressure Regulator and is Item #20 on the Pelican Diagram and is item #28 on the photo shown at this site when clicking on the part name under the CIS components heading.

http://members.rennlist.com/jimwms/CIS/CIShome.html

It's part of the throttle body.

The 'loping' that I am describing is more like a miss and at 2000 RPM seems to build on itself up to a buck and then escalates to a serious herky jerky. The only way to make it stop is to accelerate or rev up in a lower gear. It then goes away unlike an electrical miss would.

The idle issue is rough/poor idling, again like it's running on 4 cylinders. Adjusting the idle screw and the linkage doesn't seem to do much if anything. It doesn't hunt, it just doesn't speed up.

My next move is mixture adjustment. The lack of the throttle regulator and symptoms to this point lead me to believe that it is running extremely lean.

Again, any idea where I can get a throttle regulator?

Thanks
Bob

I am voting for the wur (problem)

Scraps point go with Pertronix, check ign wires at night & replace if arcing, check for hanging distributor weights (erratic advance), may be lean. BTDT bucking with each of the above

http://members.rennlist.com/jimwms/CIS/CISparts_ID.jpg

Someone mentioned reconditioned WUR's for about half the price of the new ones from Pelican. Are they worth the risk of a redo? Will you have to reset the CIS mixture settings when replacing a WUR? Or is is plug and play?

Guys,

I am unclear. So if I don't have item #20, does this mean that I don't need it? Do your '75 2.7's have it?

Thanks
Bob

The throttle valve (TOCPR) was used only on the '73.5 and '74 911 CIS systems; '75 on did not use them. Several of my local Porsche SC 911 buddies have recently had their WUR's rebuilt (systematic trouble shooting including CIS system pressure measurements indicated the WUR's were the problem). The rebuild turn around time was short (a week or so) and the rebuilt WUR's solved the CIS running issues.

Likely candidates include your WUR and AAR, as others have mentioned. There is a lot of info on these available via a search. You should check your control pressures w/ a fuel gauge. This will tell you a lot about the status of your WUR. Quite often these merely need to be adjusted, rather than changed or rebuilt.

I have recently tracked a bad warmup idle to a broken head stud. This is not so likely in your 75, but a pulled one may be indicated.

Check Mystery Train for his threads on the AAR.

Try disconnecting the vacuum line #25 that goes to the WUR and see if that helps. Seems I read sometning about that line that was the cause of the jerky problem at 2000 rpm.

Joe

Problem Solved
 

Well guys, I took several of the easiest suggestions and did the following today:

1) Lubed the weights/lobes on the distributor.

2) New dis. cap at the same time.

3) Adjusted the mixture 1/4 turn richer.

Everything came into line. Did some minor idle changes and set the timing back to where I had it.

It's better than it has ever been.

I LOVE IT!

Thanks for all your help.

Bob