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1980SCMan
 
Alan Lindquist's Avatar
 
Join Date: Jun 2009
Location: San Diego, CA
Posts: 398
Running on 5 Cylinders. Need an Audi Badge for the 911

1980 SC - Cyl #2 is low in compression with 210K on the motor, so it's going to be a bit lumpy anyway, but developed a miss that came on suddenly and can't imagine that the bad cylinder would cause this kind of lumpiness.

I've run two containers of Lucas fuel injector cleaner in case there was a stuck injector. Someone told me to pull the fuel line from the manifold and watch it squirt. Squirting fuel near the ignition sounds dangerous. Anybody else tried this?

I've pulled all the plugs to confirm that they looked OK - they have less than 2K miles on them since valve adjustment and plug replacement and they all were OK. I checked resistance on the shielded plug wires @200 Ohms setting and got a reading of 4.1 across all wires. That was consistent. Does it look right?

I did discover that cyl #6 does not have a plug boot. The attachment sleeve is there, but the protective/insulator boot is missing. I removed the valve cover to fish around and make sure that it was not bumbling around down there and couldn't find anything. I can only imagine that this has been the condition for a LONG time since I didn't recognize that the boot was missing when doing the valve adjustment.

Could the lack of the insulator boot cause a spark miss-fire? I'm going to get a boot tomorrow and fix that problem, but I suspect that something else is amiss.

Any ideas?
Old 12-19-2010, 05:57 PM
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Have you tried pulling/replacing each plug wire one at a time to isolate which cylinder is missing?

I have seen missing plug boot cause a miss on another motor.

You can use the old baby bottle trick to test injector spray with limited fuel spill. Take an old, clear baby bottle, cut a small hole in the nipple, and place the injector in the nipple to sort-of seal. Run the fuel pump to check spray pattern.

Incidentally, 2 of my 3 cars wear the four rings. They usually run better than the P-car.
Old 12-20-2010, 09:16 PM
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1980SCMan
 
Alan Lindquist's Avatar
 
Join Date: Jun 2009
Location: San Diego, CA
Posts: 398
Thanks Fanaudical
I didn't mean to slander the Audi. Some of them came with a 5-cyl, which is what mine is until this problem is fixed. I ran the car today and the miss seems to be gone even though I haven't found a boot for the plug head yet. Maybe just luck, so I'll get a boot tomorrow and confirm.

So about the injector - what does it take to pull one out? Do I just grab the line and pull it out of the rubber fitting? Is that all there is to it? And does turning the car to "on" fire the injector without the fuel distributor running as in the motor running?

Thanks for the reply.
Old 12-20-2010, 09:51 PM
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Join Date: Feb 2001
Location: Aspen CO US
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I'm betting on ignition here, replace that boot as suggested. Start the car and run it in the dark, watch for arching around the wires and cap.

To test the injectors on a CIS car you can use six clear bottles. Pop the injectors out of the intake runners. At 210k miles they will be a bit stuck and may require a tool that our host sells to get them out without damage.

Put the six injectors in the bottles and lift the air flow plate to "fire" the injectors. They should of course have clean spray patters and they should spray equal amounts of fuel.

One thing to note here, once you get the injectors out you will likely need to replace the o-rings on them. Also, some of the injector bungs will likely come out with the injector, they require new o-rings as well.

The injectors can be refurbished on cis cars, search for posts on this to find the company that does this.
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Old 12-20-2010, 10:00 PM
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