Loose hanging wires.....

[22229stingray81]

I'm digging deeper into the 'vette, and I'm finding more and more issues. Vacuum lines not hooked up, grounds not attached, etc, but I think I got most of it sorted out.

Anyone know off the top of their head what these two connectors go to? The green one is taped to a bunch of other wires under the air filter assembly on the passenger side. It is not the choke coil wire.

The other wire connector has been wrapped around another wire to keep it out of the way. It's black with a green strip going down it. It is coming out of a T-junction with a bunch of other wires running along the drivers side front fender.

I do have a service manual and assembly manual, but I'll be damned if I can figure out the wiring diagrams. Thanks for any input!

-Tatortot

 

[spikebot 81]

The wire on the drivers side is the engine water temp. The sencor is located between #1 and #3 cylinder. Cant help you on the wire by the choke connection

 

[22229stingray81]

Yikes... I wonder why it's not connected? I still get water temp readings in the cockpit.... I'll do some more investigating.

 

[redvett]

The green connector is the carburator dwell used with a special meter to set the metering rod dwell.

 

[22229stingray81]

Well.... that's good then! Thanks.


-Tatortot

 

[GerryLP]

Tator,

I believe that the second wire connector goes to the throttle compensating solenoid (TCS) on the left side of the carburetor.

WHen you turn-on the A-C, the solenoid plunger presses against the carburetor throttle lever and compensates for the loss in RPM from driving the A-C compressor at idle speeds. The emissions label shows what speed above curb idle speed it should be (normally about 200 rpm higher than curb idle speed, and it is adjusted with the wheels blocked and the tranny on drive). The plunger has a hexagonal head like a bolt, so that it can be adjusted by rotating the plunger head (clockwise; the plunger gets shorter. Counterclockwise; the plunger gets longer).

 

[22229stingray81]

Hmm... gonna have to pull out the manuals again and figure this out. I never use the A/C (or radio...) so that's probably why I haven't noticed. Do I need to take the air cleaner off to see the connection? Thanks again, Gerry.

-Tatortot

 

[GerryLP]

Tator,

Yeah, you are right. It is easier to see with the air cleaner out of the way.

So here is an old image showing where it is at...

I hope this helps...

p.s. The Shop Manual calls this an Idle Compensating Solenoid (ISC).

 

[22229stingray81]

You da man, Gerry, as usual. Thanks x 1000!


-Tatortot

 

[22229stingray81]

Alright, it appears MIA. The carb has been rebuilt at least 2 times in it's life, so I guess someone just left it off.

Anyone know the GM part number, or where I can find one of these things? I've searched, but it sounds like this thing goes under many different names. Does an "idle stop solenoid" sound like a proper name for this part?

Does this look like a correct part? If not.... could someone point me in the right direction? Or how about... gulp, this one? Thanks again...


-Tatortot


P.S. I should note that there is an Edelbrock Performer intake manifold on the 'vette, so if some pictures look a little weird... that's why.

 

[Wajulia]

The green wire on your first picture is used to test the dwell reading on the solenoid control of your carb. Under normal circumstances it is NOT connected to anything.

All the connections on your carb look fine to me. I think the white connector is for the coolant sensor as mentioned ealier, I will check this weekend.

 

[Wajulia]

now that I look at it more -- the white connector looks like it goes to the light on the hood.

Is that bundle in the driverside just above the wheel well?

oh well -- in any case I will look this weekend.

 

[22229stingray81]

Wajulia,

I don't think it's to the light; it's to the idle stop solenoid (or one of a million other names for it) for when the A/C is on at idle. Yes, that bundle is on the driver's side above the wheel well.


-Tatortot

 

[GerryLP]

.... I think the white connector is for the coolant sensor as mentioned earlier, I will check this weekend.

Wajulia,

Refer to L81's Shop Manual's page 8A-68, circuit 66. Black wire with green stripe goes to Idle Speed Solenoid (yet another name). The wiring diagram on page 8C-29 also shows circuit 66 (and 66A/66B).

Tator,

The solenoid you found is probably a GM-approved replacement, but I recall that with my Vette's original, the bracket is separate from the solenoid. I swapped solenoid's on Gail, but the bracket is the same, I believe...

GerryLP:cool

 

[22229stingray81]

Those cats claim (on their separate website) that they found a bunch of NOS idle stop solenoids, so they say they are OEM. I can't even find an aftermarket replacement, so I guess that's what I'll get.

Now to figure out what flippin' size screws attach them. I swear, that's my biggest problem when working on anything; finding the correct screws. Thanks again for the help everyone.

-Tatortot

P.S. I understand the procedure to "calibrate" it, but are we looking for a 200 rpm bump when it engages?

 

[GerryLP]

Those cats claim (on their separate website) that they found a bunch of NOS idle stop solenoids, so they say they are OEM. I can't even find an aftermarket replacement, so I guess that's what I'll get.

Now to figure out what flippin' size screws attach them. I swear, that's my biggest problem when working on anything; finding the correct screws. Thanks again for the help everyone.

-Tatortot

P.S. I understand the procedure to "calibrate" it, but are we looking for a 200 rpm bump when it engages?

Tator,

Those screws are approximately #3 Phillips countersink screws. The beveled shape of the screws, and by the way, the screws have that slightly head top rounded (I forget what they are called), and it helps center the bracket on the right spot. The threaded portions are machined thread. Find a screw that will thread in to figure out the thread pitch.

GerryLP

p.s. Yes. The RPM value you get from the emissions label. Make usre that all 4 wheels are blocked and your parking brake set. One never knows what freaky thing a solenoid may do (like perhaps is set to 6 RPM's higher).

 

[22229stingray81]

I must sound like a broken record, but thanks Gerry! I'll probably get my neighbor to sit in the 'vette when I'm adjusting just in case! otfl


-Tatortot

 

[GerryLP]

I must sound like a broken record, but thanks Gerry! I'll probably get my neighbor to sit in the 'vette when I'm adjusting just in case! otfl


-Tatortot

No worries. We all have had a few questions concerning our beloved L81's .

 

[VetteV8]

DWELL meter, what does it do these days?

I have read in a number of threads about the dwell wire on the carburettor.

Now, I am old enough to remember what the purpose and use was for a dwell meter; but that was in the times we were still bothered by setting the points on the distributor correctly.

This is not the case now, and certainly not setting or measuring the dwell angle on a carb.

Could some of the experts here please tell me what a dwell meter is used for on a '81 C3? what does it do, and what do you adjust on the carb to get a 'proper' reading; and what is proper anyway.

I am toally confused........but know that help is on the way here!
Thanks,
Cor

 

[Peer81]

In short

The primairy jets in the carb are controlled by the ECM by a solenoid. When the solenoid isn't energized the jets are in the up position and giving a rich primairy fuel supply. When the solenoid is energized the jets are down and giving a lean primairy fuel supply. As your ECM is trying to get as close to the perfect A/F ratio of 14.7:1 it has a duty cycle of 10 per second to energize and de-energize the solenoid (so to say from full lean to full rich.) By setting the idle air valve on top of the carb (and with your dwell meter) you can get the average that the solenoid is energized to 50% (that is the 30 degrees on the 6 cyl scale) at that point the system is in balance and capable to go 50% to the lean and 50% to the rich side. That is about how it works ...

Greetings Peter