where is the computer located & what does it control besides fuel/carb?

 

Look in the battery box behind the driver's seat. It controls air/fuel ratio (once up to operating temp), ignition timing (beyond base), emission controls (AIR pump, etc) and torque convertor clutch. For such an early system, it did very well. My memory is a little vague, but it may control idle speed as well. Someone with a 1981 will chime in.

Steve

 

That's pretty much it, but it does not really control TC lockup. It is a great system, stupid in the best possible way, you can out smart it and make it do anything you want.

God bless, Sensei

 

how do out smart it???????

 

I have the same question and what "out-smart" options are there?

 

I have an 81 4 speed, now a 5 speed. I'm not sure you can out smart it because it isn't that intellegent. I know most have eleiminated it, like myself. You need to change Distributor to a 80 style with vacuum advance and I would tell you to change carb to a 80 style (Holley, Edlebrock Q jet) others will tell you you don't have to change carb. I would do it so you have control settings which the factory doesn't have.

I did not have have an automotic trans but I think the computer monitored the torgue converter, others my help you here.

The computer really didn't do much, nothing like a computer now a days

 

Okay, here goes again:

The computer monitors engine rpm/ vacuum and O2 content in the exhaust to set the ignition advance at the distributor and air fuel mixture with the carb.

The carb is a large cfm quadrajet that has all the performance capabilities of any other quadrajet, only it is more accurate in it's fuel metering. You can modify it like any other Q-jet for performance. The computer will keep your mixture at optimum efficiency for normal driving, and will flow all the fuel you set it up for at WOT.

The timing is far from performance oriented if left stock, but by simply advancing the base timing to 14BTDC vs 6 BTDC, you can get pretty close and the computer does not know the difference (it does not try to outsmart you). With a $150 chip, you have a performance timing curve that will never fail due to weak springs, moisture. dirt, etc.

If you go with a radical cam, the vacuum sensor may think the engine is under load and retard timing and richen the fuel mixture. For about $20 worth of parts at Radio Shack, you can build a voltage regulator circuit and adjust the overall signal level from the sensor to the computer and fix the problem.

The 1981 CCC system can give you optimum performance and optimum fuel economy. All for less than $200 (not counting other engine mods, cam, pistons etc). Thats less than a cheap rebuilt earlier model q-jet! I can't think of one good reason why anyone would downgrade their '81 to pre-'81 carb and distributor, it is just throwing away money.

God bless, Sensei

 

Sensei - Thanks for posting the information. How much "peppier" will it feel with 14 degree timing vs the 6 degree timing? Any difference 0-60?

 

I think you can accomplish much the same thing by advancing the base ti,img. It won't pass smog but it'll run much better and faster. Just keep on advancing the timing a couple of degrees at a time until it pings badly and then back it off a couple of degrees. If you go too far, you'll even get surging at hiway speed. Yhat's exciting but not in a good way.

You can also get it to run richer by pressing the pedal to the floor. Pretty simple.

 

i threw out my ccc, carb,transmission, dizzy and the 25 lbs of wiring that comes with it . like sensei says if its in good working order then there is nothing wrong with it but i prefered a stand alone dizzy with a non choke/electronic carb and a transmission which will accept a 3000 stall without the loc up so it all had to go. i had no need for smog and all the related sensors so without all those things i didnt trust a 25 year old computer to keep it running as it should.

 

I took out all the smog stuff years ago and the computer never noticed. Like I said, it's stupid in the best possible way!

God bless, Sensei

 

I got my motor out to be replaced with a new crate motor. The computer is not going back in, I already have a new distributor, carb. What must I do to keep my lock up converter working?

 

well that should send warning bells ringing at how uselesss it really is ( maybe not back then but now). what was the computer that came out in the early 80,s ? nintendo , commodore 64 or something like that..they have come a long way.

 

There are two switches on your brake pedal. One switch turns power on to your brake lights. The other disconnects the power to the torque converter. As long as you have 12 volts to that switch, it will work.

God bless, Sensei

 

I am very interested in the 20$ radioshack voltage regulator circuit as this may fix my issue I am having.
For starters... I have a 1981 corvette, it stopped running one day and I diagnosed it as a timing chain/gear failure. I took the front apart, and replaced the timing chain. The engine now ran, but terribly. It backfired through the carb with any press on the accelerator. Took to a mechanic and found a whole host of issues. We had the heads rebuilt, new lifters put in, and it needed a new cam shaft as the old one was going flat. mechanic got it all back together but is having issue with setting base timing. He can set it to 10' BTDC with the CCC disconnected but as soon as it is reconnected the computer changes it to 30'BTDC. The car starts and idles well but when pressing the accelerator it give a very loud backfire through the carb. Mechanic described it as a lean condition. The way it was explained to me is that the CCC is changing the timing, and setting the Q-jet to be too lean. maybe due to the new camshaft? The cam that was put in was "stock" with no extra lift but maybe its still throwing it off. I would really like to keep the old CCC and Q-jet in place but this mechanic and every other one in town has told me to get a new vacuum advance distributor and new carb put on it.

Any help would be appreciated, thank you!

 

First off this is a old thread and you should have started a new one to save people from reading old posts. Anyway if you think the CCC system is causing a lean condition you can unplug the m/c solenoid from the carburetor and the carburetor will default to full rich. Then see if the lean condition still exists. Keep in mind the idle mixture and the secondaries is not controlled by the ECM. These days no one tries to fool the ECM by adjusting the voltage to sensors. It's sort of a caveman approach to tuning. Burning a new chip is the proper way to remap fuel tables.