randy78045

Here is the deal... After my engine is totally warmed up (30 minutes or so) the air/fuel gauge goes totally red (lean) and ultimately the LEDs just dont even light up. I have checked the windows in the carb and there is fuel in the bowls. The regulator is solidly at 7 lbs of presure. I cant hear pinging, but the pipes are too loud, and I really dont feel a performance problem (though I dont drive the car hard when this happens cuz I am afraid of detonation). I suspect maybe the O2 sensor is bad cuz in the morning after the engine is cold, the engine will run somewhat lean, but within a 1/2 mile the gauge will read normal again. What do you Motor Gods think? Am I missing something? Are there mechanical problems that could cause this? Oh, and when the car was dyno'd it showed that the engine does run lean in the lower rpm range. Any help you all can give me would be appreciated. Thanks...

monkeydude3

definitely sounds like a problem with either the 02 sensor for the gauge or the wiring to it

randy78045

The thing is, the gauge shows lean in the morning when I start the engine (which is not typical) and then seems to show normal after a 1/2 mile or so... why would it show lean in the morning if it were a "hot" sensor or something?

turbostang21

if you are basing this on a blinky light a/f guage that uses the stock narrow band o2 sensor that is your problem. they are useless and do nothing to show an accurate a/f ratio. you need a wideband o2 for this. the dyno uses a wideband sensor so that is accurately showing you that you are lean up top...not the best with tuning carbs. if you like the blinky light keep the narrow band a/f gauge...if you are trying to tune with it throw it out of the window when you're going over 85mph

monkeydude3

u know i have a light show a/f gauge tied into my factory o2 sensor and it doesn't doanything for about 2 minutes... the 02 sensor has to warm a bit before it gives you a signal.

want to know if you are running lean? Pull your spark plugs... if they are grey and all look pretty much the same, you are fine. If you are indeed running lean they will be more white than anything

randy78045

No one is tuning by this guage. The question is: is the O2 sensor bad an showing a false reading or is there a mechanical reason the car would go severely lean as the gauge indicates.