[rtuey]

I'm trying to diagnose intermittent starting problems here my '82 911SC just cranks but there is no firing. After lots of other checks, I want to check out the cold start valve, but can't seem to find it.

I'll mention my symptoms and diagnostics steps so far, in case you have some other good ideas.

Symptoms:
Warm day of about 70 degrees - filled car with gas and had a little trouble starting. Car sat in garage for about 1 hr. Tried to start - it just cranked. When it does start (even on very warm days), it severely hesitates or stalls until the motor is warm (above 1st hash mark on engine temp). I have to use high revs to make sure I get across the street.

To try to fix this problem on prior occasions, had previously:
1) replaced O2 sensor relay underneath passenger seat
2) replaced all 6 spark plugs
3) check continuity & resistance of all plug wires - within range
4) checked rotor & cap - used sandpaper to remove burn marks. Both had been replaced about 6 months ago. Rotor resistance was a bit high.
5) checked fuel pump by bypassing fuel pump relay circuit
6) swapped out fuel pump relay to see if that would help.
7) CO mixture has been richened by putting the allen wrench into the mixture control unit and adding 1/4 turn counterclockwise.

Would appreciate your guidance in locating the cold start (enrichment) valve for the '82 911SC. The 911 Workshop Manual (p. 164) fuel system schematic picture seems to show it at the back-left of the engine compartment below the intake boot. To get to it, you are supposed to remove the "auxilliary air device" from the throttle housing. I can't find that either.

The 2nd attachment is a picture of that area. Can anyone put an arrow on which component is the air device or cold start valve? The 3rd attachment is pg222 of the manual which shows how to remove the valve.

The 4th picture is on the right side of the engine above the #5 spark plug. What is the gold looking round component with the open hose attached? Is it supposed to be disconnected?

Help and suggestions are desperately needed. I contemplating attempting doing an engine drop (my first try) to work on this and replacing the boots and vacuum hoses. The engine has around 230K original miles, and 135K on the clutch.

[VaSteve]

I think its the green plug in the second photo.

[tdatk]

7) CO mixture has been richened by putting the allen wrench into the mixture control unit and adding 1/4 turn counterclockwise.

I believe it's richer = clockwise.
Excellent post (I love pictures of schematics) and VaSteve is right.

[type954]

To me, 70 degrees is too high for cold start valve to "activate" (?), at least with CSV's on 914's (not to say any connection to 911's), the temp has to be really low, like less than 40, for the CSV to affect anything. On my '83, the hose that you show disconnected, is connected but the hose routes around to the back of the engine to some place I couldn't easily see but I think it's plumbed into a vacuum port so that could be a source of a vacuum leak. Vacuum leak then routes un-measured air by the throttle plate (or what ever the CIS uses to measure air flow) and results in not enough gas fed to the injectors causing low idle. That piece looks like a decel valve on my '81 L-Jet Vanagon, so I'm going to say its a decel valve. This is educated guess as I'm no expert.

[KFJ]

The vacuum line in picture #4 goes deceleration valve.

I would recommend getting the AAV hooked up, then get/borrow a gauge and read control pressure at cold and then warm. Then, get a gas analyzer and adjust fuel mixture. Do this before replacing any more parts.

[86911TLCAB]

VA Steve is correct...

Also verify the plugs wires are correctly aligned... sounds like a big air leak...

just for info: You can do a partial engine drop and have sufficient room to get at all the hoses and connections...very easy to do...

http://www.pelicanparts.com/techarti...ngine_drop.htm

[OldTee]

Originally Posted by tdatk

7) CO mixture has been richened by putting the allen wrench into the mixture control unit and adding 1/4 turn counterclockwise.

I believe it's richer = clockwise.
Excellent post (I love pictures of schematics) and VaSteve is right.

Correct: Rightie richie, lefty leanie.

I suggest you stop until you get a better undrstanding of the CIS system. Messing with the mixture can get you into a world of hurt. Follow what people are suggesting here. Check your control pressures. Make sure you have no air leaks. Where are you located?

ARF

[Dr K]

Originally Posted by OldTee

Where are you located?

Redondo Beach, CA. How did you find us??

[86911TLCAB]

out of curiosity once the engine warms up, does it then run without all the hesitation etc?

[rtuey]

Originally Posted by 86911TLCAB

out of curiosity once the engine warms up, does it then run without all the hesitation etc?

The cars runs fine if I can get it started and warm. I'm just afraid to take it very far, although I intentionally got the Premium AAA service to cover 100 mile towing.

I appreciate all of the quick answers and advice. Since reading, I've downloaded copies of the half & full drop articles from Pelican. I do have both the 101 Things & Rebuild books by Dempsey. (I keep intending to drop them off at the El Segundo Pelican office to ask him to autograph them - it's about 5 miles from my house.)

So folks think that green connector in the picture is the cold start valve. Does its location make at least a half-drop required?

How many feet off the ground do I have to jack up the car to do a full drop when using an ATV jack to support the engine?

Additional follow-up. I checked my repair notebook and saw that I wrote "1/4 turn clockwise on CO adjustment". Apparently I got it right, but it didn't fully resolve the problem of hesitation when 1st starting the vehicle after it has been sitting for multiple hours.

By way of further diagnosis info:
1) the distributor rotor resistance measured at 4.84Kohms. The Bentley pg 280-8 says it should be 1Kohm for a standard rotor, and 5Kohm for Rpm limiter rotor. I just purchased whatever rotor they give you for '82 SC from Pelican Parts.

2) OEM CDI & coil was replaced in Oct 2005 (215K miles) with Permatune 911SC902 (from Zims). At that time I was having a similar problem. I wrote "Car still runs very rough - pump gas to start; backfires when tries to start. Once starts - stays at 900 rpm idle. However, stalls when try to accelerate."
(I managed to have the shop solve the problem by discovering I had stupidly put the plug wires in the reverse order of clockwise vs counterclockwise). I have not moved the plug wires during this problem. I guess I should re-verify the locations again.

3) Plug wires were replaced in 4/2003 with Magnecor KV85 8.5mm wires at 205Kmiles
4) O2 sensor replaced by shop (Dutch Treat in Inglewood) in Mar 2010 at 225K miles
5) All fuel injector valves were replaced 3/2003 at 205K &
6) Duralube Injector cleaner, dist cap & rotor 2/2010 at 225K miles.

Rick