I was contimplating going speed density, but I'm not sure I need to. If I go SD I think closed loop is the only option for me because of the extreme weather conditions due to being here in the. My current MAF tune was tuned with a wide band put in the rear 02 spot after the cat.. so I don't know how accurate the AFR was. If I go CLSD does the Wide band feed into the PCM? or how does the PCM get its feedback?

 

Closed loop uses the stock front o2s for feedback.

 

your wide band is only there for you to log and make correct fueling changes yourself. start by putting the w/b in front of the cats. if you dont want to do it yourself then take it to a shop and have them do it. it shouldnt cost you more than 20 dollars to have it done. as for the pcm, it will ignore the narrowband 02s and use computer based calibrations(your tune) to run the vehicle in open loop. i was stationed in maine and didnt have any problems with olsd or clsd.

 

you can get better decriptions of the two on hptuners

 

I switched to speed density for my blown avalanche about 3 months ago. Had from about 9-100 degrees here and truck ran fine all the time. Very happy.

 

When using speed density, the truck needs an accurate VE table. THis value is where the pcm determines fueling. If closed loop, the PCM will trim to keep it accurate, what AFR it is commanding, during part throttle. It is affected by IAT's.

Ive been OLSD for like 10 months, both NA and boosted. no complaints.

The tune just needs to have the MAF turned off, then set it up to Fix the VE values.
Wideband will not plug into the pcm or anything, its just needed to set up the VE table in an autove type of procedure.