'82 Sc Surging Idle & Any Rpm; Goes Fine Up To Redline

[Mattcamp]

THIS IS ON MY FRIENDS '82 SC; TRYING TO HELP A BROTHER OUT;

Looking for an answer to the following problem on my 82 911SC. At idle either
cold or hot the car is searching between 900 and 1100 RPM if I remove the the
oil filler cap it settles to the correct RPM 900. Also up at running speed the
car is "surging" runs great right up to red line! But, the "surging" is there
at a steading RPM. Thanks, Rando

ANYONE EVER HAVE THIS FUN PROBLEM?

[Mattcamp]

HOW ABOUT A STARTING POINT?????
ANYONE????

[w21055]

If you hit a search it will point you in all different directions. It could be the WUR, Dizzy, vacuum leaks, fuel mixture,plug wires.

Mine bounced around and I had the dizzy rebuilt and mine is much more even.

Good luck.

[john walker's workshop]

unplug the oxy sensor, leave it unplugged and set the CO to 3.5%. you can also set the timing to 33-35° total advance.

[Mattcamp]

CO TO 3.5%?????? WHAT'S THE CO?

[Kemo]

I have a 78SC and had the same surging issue. For me, it turned out to be a failing Warm Up Regulator. Interesting enough, the Injection System you have has several points of failure that could cause the surge. With that in mind, you do need a few tools to determine what could be causing the issue. John Walker is one of the few guru's on this board, so his advise is golden. If you were to gain access to a CO monitor to monitor the Carbon Monoxide level of your exaust gasses, you can adjust the air-to-fuel mixture such that it registers 3.5%. your car has an oxygen sensor attatched somwhere on your exhaust which would need to be removed first. Then...if you can get a holt of a timing light, you should set your timing at 5 degrees Before Top Dead Center (BTDC).

Believe it or not, this is definitely a job anyone can do. I would recommend the book that Wayne wrote "101 projects" sold here on the site. that will give you the detailed information to adjust the timing and the air-fuel mixture.

In the end, if your pressure in the system is not in limits or if you have a leak anywhere in the intake system, your car will not run as good as it could.

[VFR750]

My uneven idle was solved after I replaced the voltage regulator on the altenator.

I intentionally replaced the regulator for the express purpose of fixing my pulsing heatlights. Very faintly I could see the lights change brightness as the engine hunted at idle. The lights also pusled when driving. Once the regulator was replaced the lights were steady, and the idle smooth.

Go figure!

[Al S]

Many possibilities, but the first thing I would try is to adjust the idle mixture a tad leaner. Do a search, tons of info on how to do this...

[Mookster]

DO NOT THROW PARTS AT THIS PROBLEM!

Get yourself a baseline:
1. 82 SC I assume CIS injection. Check the system with the correct equipment
2. Rule out vacuum leaks.
3. Have a shop adjust the a/f mixture when a sniffer is up the pipe.
4. Check the chassis to transmission ground strap. Old or dirty contacts can cause a lot of problems at this point.
5. Look at the spark plug wires at night and see if you see them grounding in the engine compartment. (If they are improperly grounding you will see sparks).
6. Check the rotor and cap
7. Fuel filter

Start with the basics and work your way through the problem.

Good luck