CIS for reliability and simplicity?
 

I have owned my 78 sc (Euro) for about 4 years now. As far as I am able to determine the car is all original with about 150,000 miles on it. Since buying the car I have been in the throes of raising teenage twin daughters and the car has seen infrequent use; basically I have started it and driven it about 15 miles or so several times a year.

The girls are requiring less of my attention these days and I plan to spend some time with the car. My objective is to end up with a daily driver I can enjoy, drive and polish. I am not interested in increasing performance, just maintaining it in drivable condition and enjoying the luxury of driving the dream car of my youth.

I do intend to remove engine and transmission this spring for the purpose of replacing seals and repairing a couple of small nuisance oil leaks, e.g. oil pressure sensor leak, and clean it up; additionally, as it has the "chain tension-er checks" rather than the Carrera tension-er, I plan to do that upgrade. transmission is 15000 miles off of a professional rebuild.

Presently, the car runs fine with no start-up, idle, or running problems.

After reading through many posts on the board, I have one major issue in mind and it has to do with the stock CIS system. Primarrily, I am concerned about availability of parts such as replacement fuel lines. I figure that, if I am going to go with a different fuel system, the best time to make the change will be this spring when I do the other small things to the engine. My questions are:

1. Is it still possible to obtain everything you need to service the CIS system and keep it running properly?

2. Does the CIS system, aside from the fact that it is ugly, represent the simplest and most reliable fuel injection option for 911sc? I note that in many posts, folks state it is the most intuitive system to diagnose when problems do surface.

3. If not the CIS system, which available system would be the best bet for the mundane 911sc owner who wants to avoid unnecessary complication in installing a new system and wants to avoid unnecessary unreliability once the new system is installed.

4. If I keep the CIS system should I replace the fuel injector lines as a matter or principle or is it worth waiting till they fail?

5. When stock CIS fuel injector lines do fail, what is the usual mode of failure; catastrophically, or small leaks?

I have searched the board but have had some difficulty finding posts that address my specific concerns.

I have heard there are examples of 911sc cars that have logged several hundred thousand miles of operation without major failure, I want to do everything in my power to make my car one of these examples.

Thanks for any help.

Wayne

I have been doing similar research. From what I can tell, injectors and fuel pumps are still available. Warm-up regulators are starting to get scarce but still available (and there are some upgrades out there). Fuel distributors may be rebuilt by various shops. I have found one source for new lines:

J2 Precision Hose*::*'CIS" Fuel Lines*::*" CIS ' CONTINUOUS INJECTION SYSTEM REPLACEMENT FUEL LINES

I intend to keep the CIS as I rebuild my 75 Targa, primarily because I do have experience with the system (older Audi's) and have to get the car smog-checked where I live (so need "stock" induction).

As far as whether or not it's the simplest - I guess that depends on how complicated you find it to refit something else.

CIS parts have not been made in a few years so everyone is working off inventories made several years ago. Some items are NLA such as fuel distributors and warm-up regulators and those are the toughest to get new as they show the most problems with the ethanol-laced gasolines as well as corrosion-based problems.

Its not going to be easy in some cases as Bosch has pretty much discontinued support for CIS FI so one must exercise additional diligence to properly maintain these systems and prevent trouble.

You will be happy with ITB's and EFI. Get your Dizzy recurved while you do it. Not that hard to tune and you will have the look of Vintage Porsche and the modern driveability and tuneability of EFI.
The hardest part is opening your wallet... Not sure what you are looking to spend... But 6k is the DIY price with Megasquirt for PMO ITB's. Can probably do it work less if you buy some of the items used, many spend more..
If your budget isnt going to support doing it right.. Then I would leave well enough alone. These aftermarket systems are well discussed on here and arent going anywhere. You can alway do it when something breaks.
I was like you. I had no CIS issues. I took the pluge becasue I have the bug... not becaue I had to.
Many of the CIS parts are getting harder to find. In addition to the ones mentioned by Steve.. some the the sensors are also very tough to find.

Tbitz EFI is an excellent cost effective alternative and has worked very well in my 80SC since the install late 2008. If you have any issues with the CIS I recommend to have a look at it. Actually I recommend it to anyone with a CIS equipped 911, even those with a well functioning CIS. The tbitz system comes mapped for a standard SC and works right out of the box. Install is a nice weekend job, or one longish Saturday if you get help from someone who knows 911 and Megasquirt. It comes with a an easy to follow step by step installation manual illustrated with pictures. After the install you will have increased driveability and throttle response as well as an easy to maintain fuelling system.http://http://picasaweb.google.com/T...67528328684450

the issue with tbitz is that he reuses some of the sensors, hardware, etc that are getting impossible to find. You are builing a "new" system with old parts. its cheaper.. yes... but long term users will have the same issue. Try to buy an AAR or throttle body for your tbitz system..

Also he uses a ECU that was three + versions ago. At this point it is seriously out of date (hardware and software) to the point that you will probably need to buy a new MS2 V 3.57 or MS III ECU to take advantages of MS advancements made after 2007. He also doesnt use the TPS but vacuum only which can be problematic in some scenarios. Too many upgrades to the hardware and software over the last 5 years to assume that its all just plug and play. The real issue is that because he disabled the TPS and uses the stock CIS sensors if you ever wanted to upgrade so that you could control spark, you would need to make major changes to his system. Not a good plan in 2011 in my opinion.

It is good if all you are after is "cheaper". Even it is gonna cost you $2500 all in... so its really not even cheap. Too many other great choices out there. If the poster buys his ITB's used, and doesnt use some of the premade MS parts (relay boards, wiring harnesses, but does his own) he can do ITB's for about 3-3.5k... Probably worth the extra $$ to have a up to date system.

Just my .02.

the only parts I can think of being re-used are the rubber boots for the runners and between the throttle body and the barn door. CLT, O2 and MAP sensors, wiring, the vacuum hose to the ECU and so on are all new and easily available anywhere. It is always possible to move on and go to ITBs, EDIS ignition and so on if you are so inclined, but not necessary

You may be right on the tbitz not running all features available in never versions of the megasquirt but this makes it simple to use too. Which I think for many of is good. My car runs really well and I can not think of one single feature I could wish for. If you want EDIS, its not difficult to upgrade to MSnS-Extras firmware and it will work with EDIS. Why would you want a system with TPS if it runs good with a simple MAP sensor ? A simple, affordable and robust system that uses easy to find new sensors and can be upgraded for next to no money if you are so inclined, whats there to not like ?

I thought he reused the AAR and Throttle body which are both NLA. He also disabled TPS and uses vacuum only which is an issue for some users. He also reuses the intake runners which are now up to around $300 each (yikes). I have nothing against Tony. i use his temp sensor. but reusing NLA CIS sensors and using an ECU that was replaced with an upgraded unit 5 years ago is a problem in my opinion ...

Yes the AAR, forgot about that. I converted to hand throttle so don't have AAR. And neither runners or throttle bodies are consumables and no other sensors are used from the CIS so I don't think there is a problem.

When I did the later installation of EDIS ignition I chose to use a separate ECU from MegaJolt rather than download and install the MSnS-Extra firmware because I like to keep it as simple as I can get away with. Simplicity=robustness http://forums.pelicanparts.com/uploa...1295534214.jpg

Thanks to all for the input.

I have a lot to consider as I wait for winter to end.

The Bitz EFI unit was the one thing I was looking as a possible solution. It never occurred to me that the system depends on components that would soon be difficult, if not impossible, to replace. It does sound like the most economical way to go; however, I can recall many instances where I wound up paying more because I tried to get away with paying less. As I plan to keep the car, It would probably be wiser to just take the plunge and spend what it takes to go with a modern system that eliminates future headaches or rare/expensive components.

Thanks again. I will keep reading.

Best regards

Good choice.

If you want to DIY, this forum will be very valuable because just about everything you could think of has been done and documented.

If you are not a DIY there are some experts you should consult. Steve W, Clewett Engineering, Jerry Woods Enterprises, and probably others.
The key to EFI is tuning. The Hardware is the easy part... So while a DIY can manage with Megasquirt... Professional Shops arent going to use that.. Some discussions with those who do it for a living are probably in order... There arre also a few MS guru's on here. Jaime Novak is one. He pretty much knows everything there is to know about Megaquirt.

No, no, no. Tbitz system does not rely on any components that will be difficult to replace at all ! Thats misinformation. Runners will never ever need replacing, and I doubt you will wear out your throttle body ! Don't base your decision on wrong information. I do however agree that some inclination to DIY will be beneficial with Megasquirt and that better systems may exist at a cost. I fail to see how any system not using ITBs can possibly work any better than the tbitz EFI.

So you have a source for the AAR? They do go bad. Porsche couldnt even get the AAR when I called my local dealer as part of my before purchase review of all these things. Maybe that has changed.

I also dont like the fact that all the aluminum tubbing (vacuum) is resused when using the AAR. In spite of you claiming these are not wear items. They (as well as the intake runners) can and do crack... The rubber hose on the AAR is $170! Does the rubber hose never need replacing? How long before there really isnt a market for that special hose? Pelican states " Has that intake manifold developed a crack that leaks constantly and only gets worse? Replace that pesky manifold and take that mountain road you've been dying to try out." If they were truly non-wear items, there wouldnt be a market for replacements. they are prone to cracking. Just because yours hasnt cracked doesnt mean that it shouldnt be a consideration for someone in the future. it also doesnt mean that it will "never ever need replacing" as you state..

The other thing that does happen with old plastic is that air boxes can and will get hairline cracks. in spite of these not being a wear item... they are prone to failure if they are 30 years old. They are $500!

I get what you are saying. its probably not all that common for there to be issues... But i have an issue with paying 2k+ for a new fuel system, and reusing parts that are NLA. My advise to the poster is to talk to some experts, professionals, as many people who have done it on here... and then make an informed decision. Save money now and take a chance, or go all in and be good for many years. To each his own...

No I don't have a source for AAR. I replaced mine (working) with a 924 heater valve and cable to get hand throttle. If you need one I'll send it to you for free as a gift.

I know the airboxes are prone to cracking, but believe that to be less of an issue with EFI since there are no backfires. Also a crack would mean less with EFI then with CIS as it won't screw up the fuelling as it will with CIS. The runners cracking .. never heard of it until now but I believe you. If I get a crack I will use that as excuse to invest in ITBs (for the tbitz EFI !)

I'm out of this discussion, but drop me a message if you need an AAR

Hmmm - thanks, Steve. I guess the info I've been looking at is bogus. This thread convinced me to start looking for alternatives as well.

Great car. Yesterday I took my 78SC on a 120 mile drive to Baltimore with a Porschephile passenger who fell in love with the car. I brought this car out of a 7 year nap and here are some suggestions.

First, don't assume you are going to have problems with the CIS. If it is working now it will work when you put it back together.

Now:
1: Take pictures from all angles as you remove the engine. Pay attention to where stuff attach's in the back. Take compression readings and do a leak down test if necessary, do pressure tests on the CIS.

2: then take pictures of it on the engine stand. Again from all angles.

3: Things I did were:
a) Replaced the CC with a by pass (you probably don't have one)
b) Upgrade the chain tensioner
c) remove the air pump (you don't have one)
d) replace the injector's and sleeves
e) put on a pop off valve
f) new spark plug wires
g) remove and have your alternator checked
h) replace the accumulator and fuel filter
i) have the mixture set by a professional with deep CIS knowledge.
j) adjust the valves

I probably forgot some stuff, but that is it. For over 20K miles since I did that the car has not missed a beat and drives great.

http://forums.pelicanparts.com/uploa...1295618167.jpg

Lack of knowledge and understanding........
 

Wayne,

Your concerns are all valid. And I'll try to give or share my personal experience about your concern. I also own a '78SC and '77S (with '78SC motor) which I intent to give to my grandchildren.

1). There are still abundant cheap used and new parts available. If you intent to keep your car/s for as long as you like, look forward (many years from now) and ask yourself; What CIS components would likely fail or would like to have as spares?

http://forums.pelicanparts.com/uploa...1296015642.jpg

http://forums.pelicanparts.com/uploa...1296016419.jpg

http://forums.pelicanparts.com/uploa...1296016579.jpg

http://forums.pelicanparts.com/uploa...1296016636.jpg

I'm a shop-a-holic and don't recommend going over board like what I did because this was also my concern when I bought the car 20 years ago. And have never used any of these spares yet. Name it and I'll probably have one or two of them.

2. CIS is very simple and easy to maintain provided you know what to look for. A lot of DIY'er CIS troubleshooters do a lot of guess work (intuition) and get frustrated to a point where they finally give up and switch to another system. I don't blame them. It is difficult to over come ignorance if people are not willing to learn and use better troubleshooting techniques. Every single CIS components could be bench tested by DIY'ers using simple test procedures.

3). If you are thinking of EFI, my choice would be a 3.2 motronic if that's an option.

4). The CIS fuel lines are very durable and dependable. But if yours are showing sign or wear and tear, there's no reason not to replace them. You could find replacement fuel lines from many sources.

5). The early sign of fuel line failure is seeping out at the fitting/s or poorly installed micro clamp. Stay away from using micro clamps. Due to high fuel pressures in fuel injection systems using the right fittings and fuel lines are very critical.

If you plan to get 200K miles from your car you better find some one who knows about CIS or learn yourself how to trouble shoot the system. Your '78 SC in an improve version of the VW Beetle. Lastly, what's your worry about the fuel lines? If replacing them with metal fuel lines ("81-'83 SC) would give you some peace of mind, go ahead and do it. BTW, I got 3 sets of metal fuel lines collecting dusts in my garage. My flexible fuel lines are still in excellent condition. HTH.

Tony

Tony,

Thanks for the information, it is exactly the kind of stuff I need.

I must admit to being a bit of a worry wort about mechanical failure. I will watch out for deals on the board.

Nice collection of parts. I am an admirer.

Best regards,

Wayne

With the exception of the PMO EFI I setup I've had all the others on my engine.

BITZ - not enough power for my engine, as mentioned above needs a newer MS unit with deeper maps and a TPS would be nice.

Webers - power but a pain in my rear in the cold colorado weather

CIS - Predictable, never fails to start hot or cold. Plenty of adjustment available to make great power on my modded engine. The parts while NLA can all currently be sourced as "rebuilt" or you can repair them yourself.


YouTube - 1980 911 SC Tbitz EFI on a new motor

Thats my BITZ dyno run, you can see my webers running as well under my video. Somewhere in PP my dyno sheets are posted as well.