Low O2 readings

[Jeff Rand]

I am running a stage 1 244 cu " with a sequential DFI and 72# MSD injectors and DIS- 4. I have the fuel pressure set at 45# (vacuum off) and I run Red's double pumper fuel pumps. I just replaced the O2 sensor and tried to richen up the fuel map. My O2 readings stay between .620 - .740v and do not respond to any changes that I make in the set up. My boost is set at 12# for street testing and the voltage is at 13.2. The pulse width at full boost is 15.2ms. What is confusing me is the exhaust temp. never gets above 1300F during my street tests. The plug (NGK U-5) on number 6 looks normal. My next step was to flow the injectors.
Jeff

 

[86gn]

I have always read dont put a lot of faith in the o2 reading i would trust the egt,mine were low also it was from poor grounding

 

[turbov6joe]

Unless that O2 your using is a wide-band sensor, I would take the O2 readings your getting now and throw them in the garbage...because that's what good those OE style sensors are worth at WOT! Example, my WOT O2's on one pass were in the
.500mv-.600mv range, but yet my EGT was 1300 or so out the back door; doesn't jive does it??? I sold my direct scan and now tune off of EGT and an audible knock sensor only... Good luck!

 

[Jeff Rand]

Thanks for the advice on tuning off the EGT. Maybe the better way to spend the money is to get a chasis dyno tune and dial in the map off a wide band O2 sensor.
Thanks Again
Jeff