83 Suburban Running Rich and Throwing multiple Codes

[83burban]

I have an 83 suburban with a rebuilt 350 motor and a rebuilt computer controlled carb on it (this is a California vehicle). Both carb and motor have less then 500 miles on them. Here's what I know:

Engine runs rich:
I can smell gas and it has little puffs of black smoke when I rev it

As of yesterday - before adjusting the high idle - the motor pulled a constant 10 lbs of vacuum at idle in park (no fluctuation of the needle at all, just 10 lbs.)

Timing is good, forget the value. The dizzy has the ESC, so no vacuum lines there.

I will check the plugs later today for color, when I do an oil change and update.

Everything tune-up related has been done, filters, plugs, wires, cap, rotor, even did the coil and fixed all the grounds.

Check Engine Light: I cleared the computer when the swap was done (so these are current codes)
Engine throws codes - 12, 13, 21, and 34 - tested by jumping and counting

Light comes on only when I idle and will stay on until I turn the car off - funny thing though - If it turn the car on and jump onto the freeway and cruise the light will not come on until I slow to an idle (I believe that the idle circuit is running rich but am not familiar with the q-jet)

I have a new O2 sensor, coolant temp sensor, and ported vacuum switch that I will be putting on today as well, they were all broken by the POS PO.

What I need:
How do I tune the q-jet to run better (less rich). I am familiar with Holley - have always just tossed the q-jets. And finally - what are codes 12, 13, 21, 34. I think that 12 is diagnostic, and 13 is bad O2 but everything I have read says 21 and 34 are MAF sensors or TPS sensors (stuff this burban does not have).

Thanks for the help and let me know if you need any other diagnostic info

[72 CustomCamper]

My book says code 13 is a O2 sensor code, 21 is a Throttle Position Sensor code, and 34 is for 84-86 Differential Pressure code and for 87 only is a MAP Sensor code...


Chuck

[83burban]

72 Custom: Thats what I got from all the code readers but it cant be right. I have an 83, so there is no MAF sensor or TPS sensor either. Correct me if I am wrong, but I believe that this was the first year GM used a computer on a vehicle, so possibly they have different codes?

What is differential pressure code mean?

Got the plug checked out - they are normal all except for excessive darkening which just confirms my theory of running rich. The electrode is tan and the straps are ashy, the base of the plug is sooty black.

I have to keep this truck smog legal, so I can't leave anything off or bypass any smog stuff (wish I could), and the check engine light cant go on.

How do I adjust the q-jet? Are there any tips experienced guys can give. I took it to a shop today and spent 65 to have them do stuff but it didn;t make any difference.

[lurch115]

Originally Posted by 83burban

72 Custom: Thats what I got from all the code readers but it cant be right. I have an 83, so there is no MAF sensor or TPS sensor either. Correct me if I am wrong, but I believe that this was the first year GM used a computer on a vehicle, so possibly they have different codes?

What is differential pressure code mean?

Got the plug checked out - they are normal all except for excessive darkening which just confirms my theory of running rich. The electrode is tan and the straps are ashy, the base of the plug is sooty black.

I have to keep this truck smog legal, so I can't leave anything off or bypass any smog stuff (wish I could), and the check engine light cant go on.

How do I adjust the q-jet? Are there any tips experienced guys can give. I took it to a shop today and spent 65 to have them do stuff but it didn;t make any difference.

sounds to me like your carb. doesn't need to be tuned, it sounds like it needs a rebuild. Which is pretty easy to do on a quadra toilet...have done so many that i could almost rebuild one with my eyes closed. it sounds like your float is either stuck, or binding on something and causing an almost flooding condition.

[72 CustomCamper]

I'm still new to computer controled vehicles. My dad has an 84 pickup that only has ESC, my blazer has a computer but the only thing I've had to check is the EGR code...


Chuck

[gchemist]

My 83 had a vacuum line distributor. The ESC retards timing only when the it detects pinging. California trucks are wierd. Can you post a picture of the distributor and carb?
http://www.freeautomechanic.com/diag...blecodes5.html
12 No Distributor pulses
13 Oxygen sensor
21 Throttle Position Sensor

[83burban]

California trucks are ridiculous to say the least. I will get pictures tomorrow when I start fussing with the mixture screws try to get the AF ratio back to normal.

What I am still stuck on is these engine codes. I am going to replace the O2 sensor when I get the AF ratio back so that I don't foul the new one up. But where is the MAF and TPS on this thing (are these sensors even on there?)

I am guessing the MAF or something similar is inside the carb but am still going to have to research this.

Thanks for all the help

[83burban]

Well after doing some more research on the subject it looks like lurch115 got it right.

The TPS and the MAF are both sensors located inside the CCC quadrajet. Looks like I will keep this one on the truck for now and head to the junk yard to find myself a used carb to rebuild in the interim.

Hopefully, this will clear all the codes that I have and keep the truck and smog guys happy.

Thanks to all who replied and helped out.

[gchemist]

Do some research over at www.thirdgen.org. Those guys have great information on carbs, TBI and other fuel systems.

[JCampbell]

I know, waaaay old thread, but I'm seeing similar symptoms on my 84 C10. Any update on any of this.

I'm a CA guy, too (unfortunately).