well i was just wondering? isnt it when there is alot more air than fuel in the mixture? because on my A/F meter when i down shift in any gear without feeding more gas it goes completely lean on my gauge. i would think this is norm, but i jus wanna make sure nothing is beiing harmed. also at idle my AF is all over the place from lean to stoich then rich constantly changing. is this norm too ? its a 97 RS 5spd. just intake , exhaust, and 75 shot Zex kit which i barely use. (results were without use of nitrous)

the question of this forum should be, why did you change that beautiful eclipse back end to the supra style?

Originally posted by 420a2ner
the question of this forum should be, why did you change that beautiful eclipse back end to the supra style?

Agreed. Wonder who hes trying to fool? If I saw that my reaction would be "WTF?".

good for you but the question still remains.

Everything is fine. When you back off the gas with the car moving, the injectors pretty much shut off, with very little fuel going into the cylinders. You notice this on the A/F gague as very lean. It's completely normal. The cycling of the A/F gauge back and forth is normal also, as it's reading off of the o2 sensor's output. The ECU cycle's this sensor to constantly acheive stoichiometric A/F ratio (approx 14.7:1). That's one good thing about those blinky light A/F ratio gagues..lets you know if your o2 sensor is working correctly.

ok thanks. so only time i would have to worry is if when i am feeding gas it reads lean correct? (which has never happened yet).

Originally posted by 97grnRS
ok thanks. so only time i would have to worry is if when i am feeding gas it reads lean correct? (which has never happened yet).

The only time the A/F gauge should NOT cycle back and forth is during open loop mode(engine warm up, and going WOT). If you are flooring the gas, and it reads lean, then yes, that's not good. Also, you can't feel detonation, and it's fairly hard to hear also, esp if you have windows down and radio on, ect..It's not like a misfire where you can feel a difference in the motor. If you are not boosted, then it's fairly unlikely that you are getting any detonation, unless you are severly lean for some reason..

you only get detonation while running lean right?

Originally posted by eclipse982nrRST
you only get detonation while running lean right?

It can be caused by a myriad of reasons.



Edit: Here is a good post by Gary explaining a few things.

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=10494&mesg_id=10494&listing_type=search