There are injector holders that unscrew (female hex facets), and there are ones that just pull out (but not very easily). Mine pull out, but I wish they were the screw-type. I think they all take the small but thick donut o-ring, which can be found cheaply at any autoparts store. I think it's probably the same as virtually any other CIS injector car.

Re vacuum leak from injectors: I have seen very loose injector seals without giving problems because, once the engine runs, the suction in the runners seats the injectors somewhat. Replacing the O-rings is good but, check EVERY hose and hose-clamp, get new gaskets and boots for the intake runners, inspect the pop-off valve, etc. In the past, a lot of leaks came from the gaskets where the the intake runner mounts on the cylinders. Porsche replaced the 2-bolt connection with a 3-bolt connection later on with the 964's? Another leak source can be both hoses from the oil filler pipe: one goes to the breather cap, the other to the boot on top between airbox and throttle body. Make sure there is a clamp on both ends.

I have ordered the sleeves also after knocking the remaining out of the intake runners has the O rings where all hard. Might as well change it all while I have them off the car. I have taken the time to clean up the engince a bit, and also changed the o-ring found on the oil thermostat since the CIS is removed.- Also have removed all smog related items from the engine AAR etc. and blocked all their related vacuum sources. Also thinking of removing the decel valvce - any thoughts on this? WIll post additional picks soon. Thanks for all the help.;)

folks, put everything back together and I am still getting a miss when the car warms up. After starting up can drive around for about 30 minutes with no miss, then it starts up especially changing into 2nd gear. I have sealed everything up on the CIS, my WUR is about 5 months old - I can't figure this out. Any additional advice would be greatly appreciated.

Have your mixture tested/adjusted with a CO meter. JW recommends rich around 3.5% Also, check your ignition wiring. After dark, with the engine running, open the lid and check for ignition sparks jumping from the wires. SmileWavy

Gunter I actuall did that last night before reading your post - excellent suggestion though. today I checked my injectors by having my wife turn the car over and two injectors squirt but they are not as "conical" as the others. May have to invest in two injectors as spark is good, no air leaks that I can find. Thanks as always for the advice guys. below are when I put the CIS together with the runners attached - looking like a mechanical spider - found it easier to install this way making sure all the runners are on propertly other pic is it installed and with my healy sprite.

http://forums.pelicanparts.com/uploa...1101595883.jpg http://forums.pelicanparts.com/uploa...1101596191.jpg

If the car still has points, then check your timing and dwell (point gap) if you haven't already done so. What is the condition of spark plugs, plug wires, distributor cap and rotor? Jim

Jim I replaced the points with a pointless system 2 years a go, the plug cables are fairly old but I checked them in complete darkness and there is no arching. All the plugs almost new bosch platinums that show some black carbon but not excessive. I pulled each plug at ide and each one had an effect. I'm thinking now it is either two injectors I have that seemed to not have the perfect conical discharge (even after I soaked them in techron for a qeek) or the fuel pump gettting defective and not maintaining the sufficent pressure making my car run lean as a result. I need to find out if the pump is operating correctly - what pSI is optimal because I think this is the problem at this point

For 1977 911 CIS system pressure is 65 to 75 psi. Spark plug wires could have an internal flaw that manifests itself (opens up) when warm, causing miss. Lack of arcing only proves the insulation is still okay. Jim

good point

Yes to fuel pressure check. Couple things not connected to your problems: General consensus seem to favor copper plugs, not platinum. And: Isn't there a recommendation to go back to the 11-blade fan for better cooling? Something to consider in the future. Cheers.

Yea I know I should change the fan, but you know how it is, car funds are competing with my two year old. The car's temperature has not been a significant problem though since the exhaust has backdated headers and no thermal reactors. Will update soon.

I will also update the plugs - there seems to be no difference in performance anyway.

Yes, $$$ is always an issue. The 2.7 liter is a maxed-out 2.0 liter and with the increase came a problem with heat dissipation, ergo the fan-upgrade. Try a fuel pressure test. Trouble shooting is a process of elimmination; find what works. You'll feel sooooo good when you finally find it!

Guys I am ready to shoot this motor. I took the car out for a spin to get gas, still having the slight miss. I appeared to run out of gas, I got new gas and cranked it up. It would idle fine, but when I pressed the gas it would act like it was not getting fuel and backfire/pop etc. I finally tried to coax (sp) the car back to the house, car backfired like never before this time. IT finally died on me, no matter how I cranked - no start. I pulled on of the injectors while cranking, it pulsed once, and then dribbled - so I though aha - fuel pump. I let the car sit a couple of hours in front of someone's house then came back and It cranked up the first hit but still running rough. Next day I drained the gas tank. day after I replaced the fuel pump since mine was making a lot of noise. I did not have a chance to test the pressure in the system since I cannot find a shop to take the car now (I just ordered the system from JC whitney). THinnking this would solve the problem - cranked it up - still running rough even after trying to adjust the mixture it has a slight miss.

what has been changed the past 6 months:
cap and rotor, plugs, fuel filter, fuel pump, Fuel Accumulator, WUR, added pop off, changed all seals/sleaves for CIS system. Changed two injectors that worked but didn't have the smooth conical shape. Car has no exhaust leaks from the heads.

THings left - plug wires, take apart fuel distributor

HELP!

You mentioned that you've tried to adjust the mixture. Have you had the mixture checked yet with a CO meter? Find out where your actually at.

I've been able to adjust it previously without the meter to good results so I have a good idea of the mixture - can't find the sweet spot like before.

I recommend you do the system pressure tests before spending any further time on the system; certainly do not "throw more parts" at it. Once you have the pressure test results the trouble shooting guide from one of several good books/manuals covering the Bosch CIS systems will help take you through finding the source(s) of the problem(s). If you need help with the troubleshooting there are numerous people here on the board that have the information. Once it's running well and if well maintained a Porsche 911 CIS system can run trouble free for years. Jim