My 1973.5 (FYI, this model was the first production car in world with CIS) runs great since I got it in 2002.

What have I done? Adjusted the mixture, once, when I first got it. Was hard to start until I reattached my Cold Start Injector. Accumulator failed, replaced. Failed to keep in tune, huge backfire, replaced air box. The plastic thingy for my hand throttle failed last month, replaced, fixed.

An old saw about CIS:

"There are three types of CIS Owners:
1) The guys with working CIS systems are probably out driving their cars so they won't reply.
2) The guys that tinker with their CIS systems and have them royally screwed up will keep you running in circles with suggestions.
3) The guys that have spent a fortune on Webers or after market EFI will tell you they're great to justify their expenditure to themselves.

Your choice."

Very interesting!

Pardon my n00b questions...

CIS = mechanical fuel injection (not carb)
No ECU.
Uses distributor.

Bitz kit = EFI system (controlled by ECU, not mechanical)
Has ECU. (When people say MegaSquirt, they are referring to EFI ECU?)
Uses distributor.

What is the name of the product that you used to eliminate distributor?
EFI. ECU. Coil.

I replaced the CIS in my old 911 with carbs, best decision ever. One of my 911s right now still has CIS, and the only decision I need to make is carbs or EFI :)

bitzracing kit = replacement of fuel intake system. replaces CIS.
ms = megasquirt = computer = ecu
-------------------------------
first i swapped CIS with the bitzracing fuel injection system. This comes with fuel rails, new style injectors, and a megasquirt 1 computer. This completely replaces the whole CIS system. Ignition stays stock with distributor, CDI, coil. Throw away FD, accumulator, WUR, AAR, AAV, decel valve, FV, lambda brain, etc etc.
--------------------------------
Second, i swapped my broken ignition system with electronic ignition: i upgraded the megasquirt 1 box to a microsquirt (ms2), which can handle ignition. My broken distributor was replaced by a wasted spark system with crankfire: you swap the pulley for a toothed pulley (goingsuperfast or clewett), you read the crank speed with a VR sensor. This sensor sends signals to a Ford EDIS module/coilpack which controls spark. It makes your engine fire at 10° advance, every 360 degrees, so you have 2 sparks per '4-stroke'. One good spark, one wasted spark. No need for cam sensor thus. The EDIS module talks to the computer, which dials in advance/retard by means of a full ignition map, and sends this info back to the EDIS which sends the sparks out at the good timing.
Basically, the engine runs now without CDI, without coil, without distributor.

You could go one step further and go ms3 and drive coils directly without the need for the EDIS in-between. For me, that was too expensive at the moment.

and of course, just like with CIS, there is quite a steep learning curve, but if i had to do it again, i would decide immediately to go ms3 (or ms2) and go full modern EFI. I think you can even do it for free by selling all the worn CIS parts to the originality kaisers. :D

the bitzracing it is ideal for us noobs to learn about FI, and jump in with a more or less plug and play kit.

CIS unit restoration.........
 

Rutager,

If someone is willing to spend $5K for the restoration and calibration of a complete CIS unit, I will do it. Plus a top and bottom engine rebuild (engine parts not included) for the said amount. One more thing, I will test run the motor too before delivery. Overall, CIS troubleshooting is easy and simple if you stay away from guess-work troubleshooting.

BTW when I go to the track with the ‘78 SC, I just checked the oil level and brake pad thickness and load the car on the trailer. Strapped it and had fun in the track.

Tony

^^^ THIS. My experience as well.

FWIW, if you go with a non-stock fuel induction system and do not have the skills/equipment/etc. to do all of your maintenance, you need to find a person who is willing to work with you. This is not trivial.

Add to this the fact that to get your new induction system to work properly (cold weather, hot weather, bottom of Death Valley, hot start, cold start, top of Pikes Peak, partial throttle etc.) requires a ton of tuning. Car makers spend literally 1,000's of hours on the dyno and in the world making their maps work in these conditions. And meet fuel economy and emissions targets at the same time.

It all depends on what you want.

Also, if I really wanted to go to a more modern FI system, I think the best way is to get a complete 3.2 motor and brain and just drop it in.

While it would destroy my numbers matching 1973.5, more power etc.

Tony,

You’re an angel to the CIS world and generously help us all out at bargain prices. I was answering the OPs question based on a shop and shop prices, I figured all the consumable stuff, hoses, gaskets and lines along with a new airbox to be around $1,000; rebuilds from a rebuilding business of the WUR and FD to be over $1,500 and then the rest labor- this would be a worst case.

A mechanic who is familiar with 911s and CIS should be able to troubleshoot and repair for much less.

Best,
Rutager

Regrading AFR

whta is the best unit to purchase for non track type car. I would like to have a unit to check AFR without installing another dial etc...is there such a thing?

Carbs are cool.

With CIS, you mean?

If it ain't broken then don't fix it. Again, I have been driving K-Jetronic cars almost exclusively since 1984. No problems. I will confess to getting rid of the '83 SC computer and frequency valve in favor of the "K-Basic" design of the '78.

That said, I agree these are NOT the ideal or even the best option. Carbs are cool. EFI is cool too, but sometimes requiring significant tuning. If I change displacement, I will surely change the intake system. Frankly, the system I really want is MFI. As they said, there is no substitute.

But yeah, CIS systems work well and are reliable. In my experience. And there are many tens of thousands of them, or hundreds of thousands, running fine today. At forty years of age.

To answer your question -

- replaced leaking air box
- replaced WUR with a unit calibrated by our Tony
- replaced accumulator

Jason

Adding this thread for future readers
http://forums.pelicanparts.com/porsche-911-technical-forum/1019639-1980-sc-newbie-help-needed.html