rebuilt dualjet, now flat spot

[1clnlj]

Well took it for a ride, ran great. But 20 minutes in the dreaded check engine light came on, but after 10 or so seconds it went off and did not come back on. I don't think I have seen that light come on in 35 years - other than starting. Here is the driving scenario: car ran at idle for 20 minutes and I figured I venture out with it. Did 15 minutes of city driving then hopped on the freeway. Probably went 6 miles when the CEL came on. As I got off the freeway the light went out then drove another 15 minutes home and no light. When I got home I attempted to pull the code from the diagnostic port but all I heard was a clicking noise so I stopped. How long do you have to jump the terminals to get the light to flash? Or did a code even set since the light went out? I have yet to put a dwell meter on but I suspect one of the carb settings is not quite right.

[1clnlj]

Still having problems. Pulled the code - 44 lean. Is there an exact procedure to get this carb back to normal? I bought the Thexton 370 and 362 kits but have yet to punch out the plugs for external adjustment or the plugs for the mixture screws. Really didn't want to do that but is there any other way?

[Ethan1]

Still having problems. Pulled the code - 44 lean. Is there an exact procedure to get this carb back to normal? I bought the Thexton 370 and 362 kits but have yet to punch out the plugs for external adjustment or the plugs for the mixture screws. Really didn't want to do that but is there any other way?

 It may be idle mixture screw related or something else. What car are we talking about here?

[Ethan1]

 Oh, I see, '81 Grand Prix. It says code 44 is Oxygen Sensor Circuit related. Also, any vacuum leaks? Just curious.

[1clnlj]

No vacuum leaks, that I know of. Car runs great at idle and ran with no problems before rebuild, just throws the CEL. Dwell meter is at 18-27 degrees when fully warmed up. I can turn the idle mixture bleed in all the way and can't get the dwell above 27.

[Cliff Ruggles]

Did you install new "O" rings into the upper idle airbleed adjustment?

[1clnlj]

Did you install new "O" rings into the upper idle airbleed adjustment?

Yes, new o rings were installed on idle air bleed valve.

[Cliff Ruggles]

Did you clean the idle tubes or remove them for cleaning during the rebuild.  Even when we don't pull them out here we always manually clean them by taking an old pump return spring and straightening it out to run thru them.......Cliff

[1clnlj]

I did not clean the idle tubes. I have a guy that is going to go back through this thing and hopefully get it back up and running.

Thanks for all your help.

[Cliff Ruggles]

Probably less than 1 percent of anyone who works on these carbs even knows what idle tubes are or where they are located.  They are pressed into the main casting with tiny holes in the bottom of them.  Cleaning the carb during rebuilding often cuts enough varnish/dirt/debris loose to plug them up, and they get plugged up slowly over years of use from drying up cycles with "varnish" and other residue from the fuel.

At a minimum clean them out manually, we prefer to pull them out here and clean them with sized drill bits in a pin vise......Cliff

[1clnlj]

I think I got it. I removed the rich stop and MCS plugs and readjusted the solenoid travel to 3.5mm. Took it for a 30 minute ride on the freeway and no light.