928 Brothers

Hi,
Please help. I just did a clutch job on my car, but when I went for the test drive the car ran like s@#t. It misfires, backfires, and pops like mad. I thought it was an ignition fault, but I swapped everything including the CDI box with parts I know work. Then I thought it was false air, so I double checked all the possible leak areas. I don't want to mess with anything else because the car ran fine before I dropped the engine. Please help! The car is a 78 SC with CIS. Basically it runs like a car with bad carbs. Could the alternator have anything to do with it? What about the fuel pump?

cubiclex - 77 911s Targa

This is ironic. I too just replaced my clutch and ran the car and found it to be puttering up to about 3000 rpm, and then it finally opened up. I replaced the plugs, wires, dist. cap, rotor. The car ran a bit smoother but was still missing terribly. I then replaced my fuel injectors and wow! Problem solved. My car has 120k on it and my mechanic tells me that the injectors are often overlooked. I hope this helps.

Bill Gregory

I'll post an article on Monday that tells how to tune up the CIS fuel system, which includes changing the gas tank filter and fuel injectors.

78911SC

Bill,
Looking forward to your post... Seems I'm having a similar problem... I'll follow this thread though...

Thanks,

Charles

cubiclex - 77 911s Targa

I also will look forward to your post. Is there any trick to getting the injector back in. They do not snap in very easily. I hate to use a screwdriver to press the seals into the manifold. Any suggestions?

Bill Gregory

I used silicone paste on the o-ring to lubricate and help protect it over time (same stuff Bruce Anderson recommends using on the seals on the oil return tubes). Two silicone paste products are 3M Silicone Paste and Dow 111. DO NOT use silicone sealer, as it's a very different product. With the lubricated seals, the injectors went in with a solid push.

You want to be careful with the "using a screwdriver" thought around the injectors. You'll notice that they don't slide in directly to the head, rather, there's a composite shell in between the injector and the head. The shell is made of some light composite material (shell + o-ring only costs $4 from Porsche, so it's not anything exotic) and if you slipped, you might do some damage to the shell.

[ 07-06-2001: Message edited by: Bill Gregory ]

Greg-slant/cab

I just removed my engine to repair oil leaks. After wards it would not start. I assumed it was my permatune. After a conversation with a tech at Permatune I was convinced it was NOT the box. WEll, sure enough I had swapped a couple of wires around. When i did get it started it did not run correctly afterward. It kinda rumbled and stumbled. What I found was that I had accidentally swapped 2 spark plug wires. In trying to get the car back on the road I was a little careless about the basics. I have found through experience that if it was running fine before that it probably something easy. I would go back and check all the little stuff.. You just never know.

cubiclex - 77 911s Targa

Thanks Bill. I agree that the "screwdriver method" is a terrible thought. After calling around to the local auto parts stores, no one seems to have silicone paste, let alone heard of such a product. They do have the sealant which I understand is an entire diferent product. They also have a silicone spray. Would the spray work? On the first two injectors, I used WD-40, but they did not slide or pop in very easily and took a lot of effort. Thanks again.

Bill Gregory

I called 3M to find out who carries the silcone paste in Ft. Collins, CO, and they said that NAPA, Carquest, and Pep Boys carry it nationally (that's as close to CO as they got ). I found it at a local auto parts chain here in CT. that has alot of 3M stuff in their auto paint section. 3M said to have a store use part number 08946 if they need to look it up.

If it would be easier, drop me an email with your address and I'll put some in a small bag and mail it to you - a little goes a long way.

[ 08-06-2001: Message edited by: Bill Gregory ]