Removing CIS with engine in the car - the writeup
 

A while back I had to remove my CIS due to a blown airbox and with no garage available I had no choice but to do it without a partial or full drop, something that is usually recommended.

Here is how I did it (on a 1980 SC with backdated heat and no AC) for those that might find them self in the same situation.

Remember to mark everything as it is removed or disconnected. Also take pictures along the way. Put nuts, washer and other bits and pieces in separate zip-bags and mark them.

1. Remove the air filter and air dome that leads air to the throttle housing. Disconnect the vacuum hoses to the ignition distributor.

2. Pull the injectors, cover the holes and get the fuel lines out of the way. I wrapped them with some masking tape and stuffed them in the airbox (assuming you have the flexible kind). Also remove both the fuel lines to the WUR. Cover the connections and put some masking tape on each line where you write "WUR".

3. Disconnect the throttle linkage and cruise control.

4. Remove the fastening nuts (and washers) for intake runners 1, 2, 3 and 4. Remove the throttle spring from nr 2 intake runner. Loosen the hose clamps and remove the intake runners (mark them). Cover/stuff the holes! Support the airbox with something that doesn't scratch the engine shroud.

5. Remove the fastening nuts for intake runners 5 and 6. Disconnect both breather hoses from the oil tank. Stuff the holes.

6. Disconnect all the electrical plugs on the back of the airbox and at the AAR. Put some masking tape on each and write where it goes. Disconnect the vacuum line (fig 6).

7. Remove the top connector to the fuel filter. Remove the fuel line to the freq. valve. Disconnect the vacuum hose at the T-connector. Cover all the connections and mark where they go (fig 7).

8. Remove fuel line holder (fig 8a). Remove the nut at the back of the bracket for the airbox (fig 8b).

9. At the back of the fuel distributor, disconnect the right-most banjo bolt. This gives you access to the second right-most connector, remove it. Cover the connections and mark where they go.

10. Lift the airbox of the throttle bracket and support it as high as it will go without hurting the 5 and 6 intake runners. Disconnect the breather hose from the top of the engine (this was a struggle for me).

11. Turn/lift out the remaining CIS while making sure nothing gets stuck. You might have to disconnect the bracket for the breather hoses and get them out of the way. Cover the 5 and 6 intakes.

Installation is reverse of removal.

I had a removable engine pad (magnets) that made things easier, might be too tight with one in place. I was also not careful enough and scratched the engine shroud when lifting out the CIS. Consider covering it with something.

My car stood outside while the CIS was off and I covered the whole engine lid with a plastic bag to avoid water from getting in.

Good luck!

fig 6
http://forums.pelicanparts.com/uploa...1346438942.jpg

fig 7
http://forums.pelicanparts.com/uploa...1346438684.jpg

fig 8a
http://forums.pelicanparts.com/uploa...1346439367.jpg

fig 8b
http://forums.pelicanparts.com/uploa...1346439190.jpg

The pictures where shot at installation so they are a bit inconsistent...

This will sure come handy... I am picking up another project next week... SC. And the CIS was taken out so I need to put it all back together... Not the same as when I am the one that takes it apart... may the Porsche gods help me... and Pelican members ;)

Nice write up, I have R&R'd my entire CIS in the car 3-4 times over my one year of ownership due to a blown airbox, a second used slightly cracked airbox and finally installing my stainless airbox that I ended up pulling to repair a poorly designed pop off system.
I used a partial engine drop each time and did not have to take the runners off.
I feel like I could do it blindfolded now... :)

Here are some pictures of the CIS ready to go back in.

http://forums.pelicanparts.com/uploa...1346448043.jpg

http://forums.pelicanparts.com/uploa...1346448053.jpg

Hi, I've enjoyed your blog and also found this posting very useful. I'm in the throes of removing my airbox to try and address some vacuum leak issues and wondered if you might be able to offer a little help. I'm having a real hard time accessing the bolts that hold down runners 5 and 6 and it seems that you're removing 1, 2, 3, and 4 runners to then gain access to 5 and 6. Is that correct? Do you actually even remove runners 5 and 6? Also, any thoughts on how hard to tighten the 6 allen head bolts with springs that hold down the fuel distributor to the box. When I looked at the gasket to the airbox, it seems very dirty which made me think it wasn't sealing properly and possibly part of my vacuum leaks. The sprung bolts is a curious idea.

Steve in France, working on his 1983 911sc cab.

No vacuum at the airbox to fuel distributor seal. All vacuum is after it goes past the metering plate. It is just a dust seal.
Use 1/4" sockets, universals and extensions on number 6 runner.

are there any torque specifications for re-fixing the runners?

This is a most excellent guide! Thank you very much for posting. Just performed complete removal of CIS ('78 Targa) with engine in car in 3 hours incl. repair of airbox, and installation in another 3 hours. Car is running better than ever :)

I believe if you have tried this before, it could probably be done much quicker! A lift helps the working position a lot though.

i did my 81 w/out any drop. including the epoxy reseal to the airbox it took me 4 days.
its a lot of work, car runs totally different. to get the box back in- i installed intake runners 5-6 onto the motor then slid the box onto those runners. you can take the rubber boots and slide them on to the runners past the point where they normally sit, silicone lube works here, then once the box is in place just slide the boot home. that way there is no fighting to try to line up 50 things perfectly. using this method each runner is done separately so one can make sure each one is done right. i would say use the oem gaskets, the reintz pieces are flimsy. i sanded the mating surface on the bottom of the runners lightly atop a piece of glass and used some hitack spray gasket sealer that comes in a can for the final install

This is great. I know this is older, but bsimonson if you wanted to submit this for our DIY Project Expert Submissions you can get up to 10% off your next order with us. Info here. You could also submit any other DIY's that you have done as well.

This is great, thank you guys for submitting it. I think I may need it..,.Tim

I've removed mine with the intake runners attached makes it much easier and quicker. All you need to do is disconnect the fuel lines in the rear, electrical lines in the back, throttle linkage and cold start valve hoses. unbolt the intaker runnres and lift out.

I tried doing it the way mentioned above but it took much longer because of the runner connectors to the intake runners. I can remove mine in around an hour if all goes well.

Yes i believe this is by far the easiest way. I only removed left side intake runners. Were you able to get the whole thing out with all 6 intake runners on? That would truly be an easy job then!!

The o2 system complicates things a bit. Pre 80 would be less fiddly

Nux

Yes you can take it out complete. However i had to remove the rubber intake boot but that was it.

Anyone have tips for getting to number 6 intake runner securing nuts? I can't for the life of me figure out how to get to that rear nut.

I took out my CIS on a '79 California car. It has a really nasty EGR back in the #6 corner.

In order to get the last two nuts off, I had to use two universal joint extensions. I stuck my left hand in underneath to brace them and worked the wrench with my right. It was quite possibly the most awkward nut removal I've ever done.

Once you get the bolts, I highly recommend you use a magnetic pickup to fish out the washers before you begin lifting the runner out. If one of them falls into the cylinder, you are in serious trouble. I had one non-ferrous washer back there and it fell in. Fortunately, the #6 intake valve was closed at the time. I almost had a heart attack.

number 5 runner wouldn't come off until i sacrificed the rubber connector on the end. I cut it with my knife and then i could remove runner #5 and that then allowed more access to the nuts for the #6 runner. Got them both out of the way now but looks like I have a few more fuel lines and electrical connections to get at before it'll come out.
Say, what is this 2 wire green connector on the back? It was just dangling there not plugged into anything.

Hahaha I did the exact same today, dropping a washer in nr 6 cylinder.....😱 Eyes went black for a second.

By the way, I can now confirm removing the entire CIS én bloc - with all intakerunners attached - takes 1 hour. Assembly is maybe 1.5h but is much easier if nr 1-4 outside rubber connections are loose to allow some mild movement of the intake runners. Keep nr 5-6 firmly tight as they are impossible to tighten once the airbox slides into place. Remember to tighten 1-4 again.... Total working time incl new airbox = 3-4 hours.

all of the screw heads on the hose clamps for mine were facing the firewall. How gawddang convenient of the previous wrench to do that for me.
Another tip that might save someone in the future some time: When i was trying to remove runner number 1, it just wouldn't come out. TOok me 30 minutes to notice that the WUR body was blocking the flange on runner 1 from a clean exit. ONce i removed the WUR i could pry the runner out.

Tip number 2: Remove the deck lid. My bald head full of scrapes and scabs applauds this one.

The hose clamps for the number 5 runner for me had to face backwards otherwise the clamp and the end of the screw holding it together will contact the engine shroud.

I was able to get the number 6 rear runner nut relatively easily with a 1/4 inch flexi wobble socket (the kind where the articulation is on the socket) and a 6 inch long 1/4 extension. Remove the AAR first then attack it from front of the nut between the number 5 and number 6 runner past where the AAR was. It's fiddly but doable. If the nut is tough add a 1/4 to 1/2 adapter to the extension and use your 1/2 inch ratchet. I did it up upon reassembly in the same manner.

Make sure you account for every nut and washer (I kept a spreadsheet and numbered baggies) before you try to remove the runners because if it goes down the intake you might be cooked.

Follow up question - I need to do some trouble shooting on my '74. Car runs acceptably, but has an idle issue that points to vac leak (decal valve is already bypassed). Also is giving some illogical AFR readings at WOT.
I'd like to replace the runner sleeves and gaskets where they meet the heads (sleeves are original), as well as clean up airbox seats, clean injectors, re-check fuel pressures, etc. Can this be done without pulling the entire CIS system?
Secondly, would removing the fan housing give additional room needed, should the whole system end up needing to come out.
Thx.

Hey Charles,

The 1, 2, 3 side is not bad, 4 is maybe doable. 5 would be very tough but number 6 I can't see how it could be done without lifting the airbox out of the way. Did you mean the rubber sleeves? On the 4, 5 and 6 side they are under the airbox so I'm not sure you could reach the clamps on those. A 74 might be easier. It's not terrible to just disassemble it completely and replace all the seals and hoses. Just go slow and take your time. The phenolic sleeves are really hard to remove insitu. I think it's much safer to pull the runners and tap the sleeves out from behind. Then you haven't got junk falling into the intakes when you are wrestling with them.

If your airbox is old it will be leaking anyway. The adhesive that holds it all together typically fails on the underside seam along the top of the 4, 5 & 6 runner ports. That's how mine was. So I pulled the whole thing to remove and replace. The rubber mounts the whole CIS sits on where toast on mine too.

I just pulled the CIS from my 74 for the second time in situ - much easier / faster the second time. I don't see how you could accomplish all those replacements effectively (and not twisting/straining every muscle above your ankles) without removing it. Leave the fan housing in place- with the 74 just remove the peanut/hat and it will clear.

I did it as well, but a partial engine drop is your friend!Lifted the whole system off except the AAV and WUR . assembled and back on the same way. Great for leak checking everything on the bench and back on the car.SmileWavy

Many Thanks all -
I'm easily equipped for a partial drop, so I guess that's how I'll go - then pull the whole CIS unit as a whole and refresh.
Someone in the past has installed a pop off - so I assume the box has been off - but I have no idea if it's sealed properly - or the pop off for that matter.
Sleeves at the injectors have already been recently changed (by me) as have o-rings on sleeves and injectors. I'll re-ring the injectors when I pull them for cleaning just because I can, but the injector sleeves I'll leave lie.
Great help on this thread. I've been putting off this project long enough...

You can plug the intake and runner ports and run some low (you don't need much) pressurized air through the vacuum port on the left side. Then dunk it in a plastic storage bin full of water. You'll find any leaks in about 2 seconds.

well done! I just removed mine and what a nightmare! would you be available to help if I need to...?

Great thread, I'm fighting some vacuum leak issues and have decided to do a full CIS refresh on my '83, new airbox, and this thread will come in very handy! I intend to do a partial drop.

Don't put yourself through the pain, agony, and suffering. Drop the entire engine. It will save lots of time and hurt hands. I've been there, and learned the only way to do this correctly is pull the engine.

Thanks, I think this is good advice and I might end up doing that. I've had the engine out before to replace tranny and clutch so know what's involved (pretty easy actually, just time consuming).

For the people who continue to say drop the engine like it is any easier, I just did this and removed the CIS to address the triangle of death and do few other things.
I would do CIS removal anytime of the day over the dropping of the engine.
This is not as difficult as some people try to make it.

Don't get me wrong, if you have the space, capability and desire to remove the engine, go ahead but CIS removal is not that difficult of a job.

This step by step write up is awesome. Thank you.

Ignorance........
 

Kava,

Not until you have done the removal/installation of the CIS assembly in situ and engine out would you realize and understand the advantage of one process to another. So far, you only done it in situ. You have not even dropped or removed a 911 motor in your life. So how would you know your preferred method is better than the other. Unless you have done both of these methods multiple times, you would not know the difference. It is not how hard you did the work but how smart you did the job. The late SC’s CIS have more fuel and vacuum connections than those for mid year CIS.

Tony

Yes, it's learning by experience. That's why I said not to do it above. After I dropped my engine (with trans) for the first time as a unit by myself, I scratched my head and said "Wow, I should have done this with the CIS the first time." And the CIS went on in an hour or so, no problem with the engine out. I could see everything line up, all the manifolds (and properly tighten them), check all connections and fuel lines. It's so much easier (and better, at least to me) with the engine out. Never going to ever do it again with the engine in. Ever.

So this method would appear to be preferred, to an engine drop, to correct the TOD (Triangle of death) leaks up top. Not so if rear seal is leaking.
Seems maybe the '78 SC is one of the easier ones to remove the CSI.
Thinking I could go this route then see what remains leak wise then decide if I want to go with an engine drop.

Thoughts?

While on the project of CIS overhaul why not clean up the unused cast accessory bosses on the intake runners...

https://forums.pelicanparts.com/porsche-911-technical-forum/622947-wart-removal-cis-4-intake-runner.html

http://forums.pelicanparts.com/uploa...1534617517.jpg

A thing of beauty

On mine I see an obstruction on number 2 runner.
I see a “clean” one in your picture pic.

Guessing I need to remove it to reach the #2 intake runner?
http://forums.pelicanparts.com/uploa...1534620325.jpg

And what is it? Difficult finding it in Bentley.
Looks like a K-jetronic part in Haynes. Humm

cis removal
 

I removed an 83 CIS today due to cracked airbox.1.5 hours and off.Ciao FRED

Well I've started the slippery slope of removing my CIS at the runners.
So far I'm at about 2.5 hours not counting tool runs.

It's 102 deg here now and no A/C in garage.

The WUR was not too bad, then the runners for 1,2 were not bad. 4 and 5 are done (nuts and washers off).

I'll finish removal of the AAR and look at runner 6 tomorrow.
Hoping my 1/4" things will get me there.

Ready to do a partial engine drop too to assist in number 6 (if need to).
Quite possible the engine drop method was easier. :o
But I am going slowly with caution.

Number 5 inner was a little sticky and it needed the 1/4" u-joint and swivel.
The 3/8 one just was not letting the socket sit down on the nut.
Six point sockets are best here too.


Thoughts and prayers are appreciated! :D

Air Box Replacement
 

Is there any one in south eastern Wisconsin that has done this before? I have started and have the box out, but am not sure the best route to re-install the new box. Fuel distributer is still in car, throttle body is still in car, 4-5-6 runners are out. Its a 1979 911SC w/ A/C.

Any tips/help is appreciated

Thanks!