hey guys, just bought an evo. it has a zietronix gauge and everytime i get close or go wide open throttle the afr gauge reads what it should, but then immediately goes fully lean to 21. obviously it isn't going to 21 because when it does it pulls just fine. tried to search but couldn't find anything. if anyone knows that would be cool, thanks!

 

Its probably the most common wideband novice question known to man....
When it goes lean, are you off throttle (high vac)? ... if yes, than fuel cut condition completely normal.


Judging by your description you said 'no' to above. When the 02 sensor isn't hooked up it goes lean...so you could have a bad ground or some other bad connection. Or you could need a new 02 sensor, becasue also when your 02 sensor goes bad reads lean constantly (at least this has been my experience)

OR your tune is completely off and you'll blow you motor soon