fbarnhill

Hi,
I will be removing the intake among other stuff next weekend to do tb/wp, vacuume lines etc... I am having some powder coating and chrome plating done. Since I will be removing the fuel injectors anyway, is there anyone that offers cleaning/rebuilding for these. The car is a 79 Euro with 39k miles. It runs a little rough during acceleration. I suspect a vacuum leak since it smells like it is running very rich. Can't hardly breathe in the gurauge when it has been runinng for more than a minute. So, are they hard to get out? Can they be rebuilt? What kinds of things should i look out for. I have the WSM and will be following it but your sage advice means so much more

Thanks,
Frank Barnhill
79 Euro lite blue metalic

Rich9928p

Frank,

Have you adjusted the base CO (air-fuel mixture)? When the CIS 928s are too rich, the idle speed hunts up and down. To tune by ear you lean out the mixture to the point where this hunting just stops. It takes a special feel to be able to push down the Allen head adjuster enough to come into contact with the internal adjuster head screw - while not pushing too hard which throws the mixture so out of kilter the engine dies. It is an iterative process, you must let up and let the engine idle get back to normal.

The Porsche tech docs state that mechanical fuel injectors should be cleaned by flowing the cleaning fluid in the reverse direction as normal flow. This requires opening the spray pintle during the process. I don't think most shops have the equipment or the experience to work on these type injectors anymore. When I took my injectors to a shop they just ran cleaner through in the normal direction and they were worse than before!

My suggestion is that you purchase new replacement fuel injectors, I did this with my '79 and it made a huge difference. They aren't as expensive as the electronic ones. You should also replace the rubber grommets that fit around the injectors, I'm sure that even though the target vehicle is low miles after all these years the rubber is hard and they won't seal properly.

Only after setting the a/f ratio, fuel injector replacement and inspection of the control fuel pressure should you suspect work needs to be done on the fuel distributor. It is an art to crack open the fuel distributor and get it cleaned up so the fuel flows properly, and glue the halves back together properly so no fuel seeps out from the metal gasket. It really is best to send it in to a knowledgable rebuilder or purchase a refurbished unit if you suspect the injection just isn't working up to snuff.

fbarnhill

Hey Thanks Rich. I guess I will break down and buy new injectors. From what I have ready from other threads, you should never mess with the air fuel mixture without the machine to check it. I have come close to doing it but backed off. Thanks to your good instruction, I will give it a try.

Frank Barnhill
79 Euro

fbarnhill

Rich,
By the way, I saw the picture of your engine bay on the other thread. Man it looks great I only hope mine turns out half as nice. I am going to go with red on the tubes and the chrome powder coat on the other components. Can't wait to get started. Going to go with yellow vacuum lines.

Thanks again for your help
Frank Barnhill
79 Euro

jpitman2

To remove these injectors you need a deep socket (12mm?), and if you are lucky a sharp smack on the socket bar will loosen the injector holder from the inlet tube via the injector's hex keyed to the holder. Others here have had a very difficult time breaking these loose, but mine were not too bad. New rubber grommets will be needed and these will need some lubrication (vaseline) to get into place on the injector and into the holder. My local wrench has the gear to reverse flush injectors, but I am in Oz....
jp 83 Euro S AT 50k

Dennis Wilson

A leaking injector(s) would normally cause a difficult hot start 20minutes to 1 hour after shut down. If you don't have a hot start problem, try cleaning your fuel system with Techron or Gumout and check the wire mesh filter in the WUR. Also, how old are your plugs, wires, distributor cap and rotor? If that is all good, then try adjusting the A/F mixture.

Dennis

fbarnhill

Thanks guys,
Dennis, I did a major tune up the first thing after I bought the car. New wires, cap, plugs etc... I used the Bosh platnum plus 4 plugs. I loved these things in my 83s. This euro is supposed to have 240hp but it doesn't feel like it to me. It is an automatic and my first auto but it still shuld have some mojo. I'll find it or i'll add some later via sc or tc.

I think I am just going to replace the injectors with new ones. The car runs well. It idles ok just stumbles a little under acceleration. it just doesn't build the rpm's as quickly as it should. It feels like it's trying too hard. I think it's a vacuum leak and am replacing them all next week.

Thanks for everyone's advice
Franik Barnhill
79 Euro AT lite blue metalic

Dennis Wilson

Frank,

A vacuum leak would make it run lean not rich. Also, I've heard that the CIS system doesn't like those new fangled (that's Okie for Platinum plus 4) plugs. Do you still have your old ones that can be temporarily installed?

Dennis

fbarnhill

Hi Dennis,
Yes I have the old ones. I hate to think that those plugs are the problem. I think they were $6.00 or so each. However, if this turns out to be the problem, I will gladly replace them. What plugs do they reccommend for the CIS?

Thanks,
Frank Barnhill
79 Euro

hupp

I was advised to use the OEM Bosch copper plugs for CIS.

I also experienced a similar issue when I restored my '79. Most probable cause for running rich -- incorrect mixture adjustment, injector opening pressure too low (ie poor spray pattern) or leaking cold start injector.

fbarnhill

Thanks Scott. I will check these things when I do the tb/wp this next weekend. I will get some of the copper plugs from 928 Specialist when I order the other parts. I will take a close look at the cold start valve too.

Thanks,
Frank
79 Euro AT
lite blue metalic