87 tbi

[79jeepincj7]

Yeah I remember you doing that from the step by step part. Its been a while tho so I'll go through that again before I ask any more already answered questions about that.


The open vs. closed loop however. I know that is talked about some too but I didnt fully understand what it meant. So when its in open loop. What is it doing for running wise. Is that something that is in the tuning? Or it just means its running without looking for the data from the o2 sensors

[Bill usn-1]

Originally Posted by 79jeepincj7

Yeah I remember you doing that from the step by step part. Its been a while tho so I'll go through that again before I ask any more already answered questions about that.


The open vs. closed loop however. I know that is talked about some too but I didnt fully understand what it meant. So when its in open loop. What is it doing for running wise. Is that something that is in the tuning? Or it just means its running without looking for the data from the o2 sensors

Yes and yes.
It can be tuned for open or closed loop idle and it uses the tune at idle instead of constantly trying to correct for 14.7:1.
This is very handy when tuning for big cams with overlap where raw fuel is dumped into the exhaust. No way to get a stable AFR with gas being dumped unburned into the exhaust.
So at idle you just ignore the O2 and have the fuel table tuned for your disired AFR.

[79jeepincj7]

Alright, I guess I'll try that when it gets to that point.