Never worked on a CC qjet before I got this 84 t/a. Long story short the previous owner took this thing to local garages for everything. I have a stack of bills with the latest being "idle adjustment". The car would start up and idle at 1500rpm. The Choke light was also on because of a bad alternator which I changed the other day.

Now on cold start up it will crank and crank and sputter a bit and wont fully fire. I came back an hour later and managed to get it running, but ran rough and was very shaky it was also popping out the exhaust and if you tap the throttle it would bog down and shoot gas out the carb. The vac lines are a mess from these mechanics. The egr line is blocked off as well as the other line right next to it.

I pulled the carb off because it looked like the lower gasket was bad. Reinstalled with a new gasket. Started it up lots of white smoke and running rough/ popping. After running for about 10 minutes the idle cleared up and it started to run good. When cold you can put the pedal to the floor and it would just bog right down. But once it warms up it runs fine. I let it sit for a few hours and tried to start it again and it fired right up.

Any ideas? The previous day I shot some carb cleaner into the vac ports and down the carb.

 

If the carb is in that kinda shape, rebuild it. It'll give you a chance to determine whether the TPS, MCS, etc. are good/bad; you can seal the well plugs which are likely leaking and maybe bush the throttle shafts, which probably need it. It will take some effort to learn how everything works, but it's the only way to get it right and keep it there. Let us know before you start and we can set you up with some pointers.

 

I agree with naf on the carb rebuild and sealing the lower welch plugs, But the way it's running now sounds like fouled spark plugs from the carb being all buggered up.....

 

what they said ^^^^^

I think the white smoke on startup the next day was carb cleaner that hadnt evap'd and still in the vac lines. The idle being so high can be adjusted with the idle solenoid adjustment procedure, lots of threads here and online to help you with that. The foot to the floor bog is a well known 'feature' of quadrajets. There's an adjustment for the secondary butterfly valves that will fix that IF thats your problem. It could also be fuel related, that is, passages inside are clogged so vacuum signals arent being sensed when more fuel is needed. I'd adjust the secondaries and then if that doesnt fix things, clean and rebuild it. Its really just a quadrajet with some 'strangeness', but not too bad. Youll just need few special tools and a cheap dwell meter.

 

I have the same WOT bog problem. I searched for the adjustments for the secondary but can't seem to find it anywhere. could you please post a link?

 

https://www.thirdgen.org/quadrajet

 

Thanx lots. I had seen that a long time ago, but hadn't been able to find it since.

 

Ok an update on my problem. I had extremely bad valve seals that were just dumping oil to the point of blue smoke in hot traffic and on highway trips. New valve seals stopped all of this it also seams to have killed my 02 sensor possibly the new one I put on also. Now I had the carb rebuilt and it is running rich. I am almost positive its been running rich since I put it on. Is there any adjustments that are supposed to be done when you bolt these things on? I am getting code 24.

 

Yes.

Set your idle mixture screws at four turns out each.

Make no other adjustments to the carb until you're certain that the timing has been set to between 0 and 4 degrees advanced WITH the four wire connector disconnected. Reconnect it and verify that the timing is near 20 degrees advanced at idle and that it advances with more throttle. The exact amount is not as important as ensuring that it's working.

Plug or seal all vacuum ports.

Adjust the curb idle speed to near 700.

THEN adjust the TPS to near 0.50 volts at curb idle speed. You can use an appropriately sized roll pin to adjust the tiny screw if you don't have the special tool.

Now set IAB for proper dwell. Connect the dwell meter to the diagnostic, green lead near the blower motor. With the engine warm and the meter on the six cylinder scale look for the dwell meter to start wavering back and forth as it adjusts to O2 readings.

Turn the IAB in to richen the mixture (the IAB allows air into the idle circuits). The dwell should respond by decreasing (lower dwell = more fuel). Make adjustments to the IAB in 1/8 turn increments and allow sufficient time for the ECM and O2 to respond to changes. Try not to go in more than 2 1/2 turns out nor farther out than 7 turns.

If it doesn't respond to changes, start over with the idle mixture screws 2 1/2 turns out and repeat adjustments to the IAB until the needle begins to waver and the dwell responds to changes. If no response, repeat again with the idle mixture screws 3 turns out. The goal is to get the dwell to waver closest to 30 degrees or 50% on the six cylinder scale with the idle mixture screws and IAB closest to 4 turns out each.

You'll know it's in closed loop when the dwell responds to a rag choking the air horn by attempting to lean the mixture.

 

when I had the problem with white smoke on my cc q-jet, it was with the MCS travel being way out of adjustment.

The MCS needs to have a throw travel of I think 1.307" from top to bottom.

Maybe naf or someone else will chime in with more detail about this, BUT I think this is the most crucial part before the TPS and IAB or idle mixture screws can/should be even set.

The travel of the MCS is imperative for the collaboration of everything else to operate together. This was just my experience with the white smoke puffing out on mine (assuming the white smoke is SEVERELY unburnt fuel that is REEKING of being rich).

 

OH shoot...that just reminds me. You are hearing the clicking of the MCS when you JUST have the ignition set to "ON," right?

Because if that is not hooked up, then the MCS will be completely in the up position dumping in fuel.