hi guys, i have a 305 bored .20 over, i have a crane powermax 2032 214/220 @50 dur .452/.465 lift, and world product s/r torquer 305 heads, and headers and 3" cat back, it has the stock remanufactured 1986 computer controlled q-jet on it, i installed an autometer air/fuel gauge, and cruising around in 4th at around 2000 rpms, the gauge reads lean, at idle it stays in the specified range, but all the sudden the idle will drop a little and it'll show lean, i put CC rods in the 4bbl, and when i gun it, it'll show a tad bit rich, but never with the 2bbl, i'm sure it shouldnt show lean, it's not throwing any codes and o2 sensor is good, i have a good ground on the a/f gauge also, anyone have any suggestions?

 

How lean is it? I assume the computer is still in control of the carb and whatever O2 is connected to the ECM is working properly.

The ECM will try to keep it "round about 14.7:1." But will go a little too rich, little too lean, etc, etc if you hold it at a constant RPM/throttle position.

Your external gague might be a little off from what the ECM thinks it's seeing. Beg borrow or steal a scan tool and see what the ECM's duty cycle to the carb is under various conditions. It should be pretty close to 50% with block learns close to 128. If it's way off the end of the scale then maybe something is mechanically wrong but I wouldn't jump to that conculsion too quick.

Changing the secondary metering rods will have no effect on A/F ratio in any way below 70% throttle. Hope that helps.

What's all this about a 2bbl carb? They didn't have them on any V8 in the Camaro in 1986.

 

yes the computer is still in control, and it's a rochester e4me 4bbl, when using the 2bbl my a/f gauge is reading lean frequently, bringing the rpms up and keeping them steady, it rarely shows stoich, when idling it shows lean all the time, and even goes off the scale, where the a/f gauge will not read, the only time it shows rich is when i mash the pedal and the 4bbl opens, sometimes while idling, it'll show stoich but then the exhaust note changes and the rpms drop a tad and the gauge shows lean, the computer isnt throwing any codes, and i replaced the TPS sensor in the carb, but at idle the tps is set a little rich, i dont get it.