i need to know how to tune my carb on my 84 TA, it's the L69 engine and the 4 bbl. i need to know if i need a special tool to do it and if anyone has a web site or something to show me (or pic) so i know how. my haynes repair manual isn't helping.

 

i should also note that it's spitting black specs of something out the tail pipe. and i think it's running rich, but idunno. it sorta sounds like it's gona stall when i stop and it likes it when i hit WOT.

 

ALSO forgot it makes a really bad smell. the closest thing to place the smell to without smelling it is like if u light off fireworks and the smell that they have is sorta like what this smells like, and it BURNS your eyes if u stand by the back of my car. i'm starting to think it might even be my cat or maybe needs new plugs and wires. idunno

 

Does it smell like sulpher? That is probably the cat converter burning up. You are probably running rich.

Do you have a computer controlled carb? It will have a blue plug on the right side of the carb. If so, when was the last time you changed your O2 sensor? The ECM gets info from the O2 to adjust the MCS (mixture control solenoid). If the O2 sensor is not working properly it could be telling the ECM the exhaust is lean. The ECM then tells the carb to run richer.

Look for posts from five7kid and damon, they seem to really know their way around quadrajets!

 

How does it idle, and at what rpm?

 

Hey Chio,
You have a computer controled(CC) carb (unless its a Canada car?). When all of the sensors and computer are working correctly, the computer is always "tuning" the carb for best performance and fuel economy at part throttle. The computer adjusts fuel flow in the primaries by reading the O2 sensor. At more then 70% throttle to WOT, it sets the primarys to full rich. The secondaries are controlled by the Air Valve (AV) and metering rods, which open when you floor it at high RPMs.

 

ya i know it's computer controled, so it's most likely an O2? if so i thought the check engine light would be on for that?

 

Only if it is very bad. Stored trouble-codes are the place to start any troubleshooting on a computer controled(CC) carb. Your manual can tell you how to retrive codes using the Check Engine light. If no codes are stored, I would change the O2 sensor.

 

Read Chapter 6 in your Haynes manual under "CCCS" to learn how to check for codes. It will always flash a 12 code if everything is working correctly. Tell us if you get any other codes.

I just re-read your posts. A bad ignition system (weak spark) will fool the O2 sensor into thinking the engine is running lean, and cause the carb to adjust too rich. An exhaust leak will cause the same thing.
You should "tune-up" the ignition first. New plugs, wires and cap. Also the coil might be bad?.

 

i'm, gona go check for codes. it says to use short jumper wire to ground a diagnostic terminal. can i use a paper clip, like make the paper clip straight then stick on end in terminal B and the other end into A? and since i have a carb should i only start my car then plug into the terminal or should i only put them in and turn the key to the on position.

 

i got a code 23 mixture control solenoid. so how bad is that, and also should i try running a code running by starting the car then putting the wire in the terminal. it does say to do that with carb models but will the same code come up?

 

All right.
We check codes with the engine NOT running.
Basically 3 things can cause a code 23.
1. Bad M/C solenoid. (easy to test)
2. Bad electrical connection between the M/C and the ECM. (most likley problem)
3. Bad ECM. (I think it's OK)

The mixture control solenoid(M/C) is inside to carb. You can test it WITHOUT taking to carb apart. Its an electrical component, you need a volt/ohm meter (or a DVM). We can help you use it to trouble-shoot this problem.
Remove the air cleaner and find the 2 wire plug on the top of the carb. This is the M/C plug. Unplug the connector and use an ohm meter to measure the resistance of the M/C coil by sticking the meter probes into the connector on the carb(not the wire connector). I think it should be about 10 ohms. Next, check for a short circut inside the carb by touching one meter probe to the carb body while the other probe is in one of the connector sockets. Both sockets should read infinite resistance.
Plug the connector back in and clear the code 23 by removing the battery ground wire for 30 seconds. Reconnect and start the car.

If you do't have a meter(or know someone that does), you CAN take the carb apart an replace the M/C solenoid. But if you don't put the carb back together correctly, you can end-up with worse problems. The solenoid might NOT even be bad.
Let me know if you have a meter and how the solenoid tests. If it is not bad, I will walk you thru the steps to find out what is wrong.

 

i haven't had a chance to check the MCS but one of the guys where i work looked at it and pulled a hose off of the EVAP canister purge valve and gas can out, not gas like a vapor gas i mean gasoline so i'm gona try that first and also i need to find out what sensor is next to the coolant temp sensor, it's to the right of it and it's on the thermostat housing, he sed that might be bad too. o one more thing, is the EVAP canister purge valve suppose to be mounted to anything bcuz mine's not, it just lays in there

 

It would be a good idea to clear the ECM memory, then see if the code 23 comes back. It might have been an old error.
The canister control valve just hangs in space. Could GM have come up with any uglier way of installing that thing?
The thing on the thermostat housing is a TVS (thermal vacuum switch) which is open when colder than 85°. It is for the "EFE". It is used to divert hot exhaust gas thru a channel in the intake manifold when the car is first started. This quickly warms up the manifold. I don't think it is bad. Your Buddy might have ment the OTHER TVS. The other TVS is for the EVAP. It is mounted on the intake manifold and has much larger vacuum lines. Mine was replaced by the dealer as part of a factory recall.

 

82-12 L69,

I have a question. I am trying to determine whether my MC solenoid is bad. I ran your coil test as described above and it reads 0 Ohms. Does this mean the coil inside is bad? I checked for it being grounded out and it read Infinite Ohms so apparently there is not ground inside. I also checked for voltage at the wire from the ECM and I'm getting constant 10.8 to 11 VDC when the key was on so I dont think its a problem of shortage in the wiring harness. The only other thing it could possibly be is the ECM I guess, but my guess is the MC solenoid (coil). What does that sound like to you?

I was getting a code 23 also, along with a 45 if I remember right, but I cleared them and got only a 23 after some more driving time.

Thanks
-Ben

 

my ***, all that sh*t from a stupid little plastic canistrer. atleast soo far it was, my car runs fine now, for now thanks for everyones help. i'm gona check out the code again after i clear the system.

 

Ben,
The M/C sol should read 20 to 30 ohms. It sounds like you have an internally shorted coil (not a short to ground).

 

Ok, thats what I was thinking but I wasnt sure about how the thing operated exactly, so I couldnt make a decision on what was wrong using what I found with my new multimeter (wow they come in handy, I never realized the value of having one!)

I went ahead and ordered a new one from www.quadrajets.com for $46 shipped. Should be here tomorrow or the next day, I cant wait to get it in and see the difference. Car's been hogging has around town (not to mention smelling of gas horribly), so we'll see.

Thanks again.
-Ben