So I got my fuel tables pretty much ironed out. Im either stoich or just rich throughout the entire table. But my problem is that after about 20 min of drive time it goes into open loop and stays in open loop. The fact that it goes to open isnt a big deal but once it goes into open loop my o2 voltages go to 0-100 so its pretty lean. Then it will eventually throw a code for being too lean. What is causing it to do this. Ive richened up the open loop afr vs. coolant temp vs. vacuum to no avail. Im using a 6395 in a tbi application. Any help would be highly appreciated. Thanks

Josh

 

It's been years but as I recall the 6395 has a lean cruise mode that kinda does that. Does coming to a stop reset the 20 min thing to go closed loop for a while, and then only in cruise it goes to the lean cruise?.

Does it surge or just code?.

Given everything being right and just coding,then reset the code parameters. Trick is making sure everything is actually correct. Being able to do a double check with a WB would be a neat thing to do.

 

If I roll up to a stop light and then take off it will still stay in open loop and stay lean. But I shut it down and disconnected the batt for about a minute then reconnected it and she started up right in closed loop and stayed there for probably a minute or so then went right to open loop. It runs fine and doesnt surge but when you go to smell the exhaust its not rich like it is before. Im still a newbie so what do you mean is it just code. I mean Ive burned multiple different chips and they all do the same thing. Thats what has me stumped. I can understand the lean cruise mode but it shouldnt go quite that lean. Thanks

Josh

 

Well earliar I took it back out and it ran lean all the time and never went into closed loop. So after some thought I thought well maybe the injectors died again on me. So I went back out and fired it up and voila it runs in closed loop and all is good. So i take it for a qiock trip and after a while (5-10 min) boom it hits open loop and goes way lean. I got home and looked at injector spray and it looked to be good. On a side note Im my injector pw is 2.3x at idle and goes to 7.4x msec at moderate throttle at about 4000 rpm or so. I think it is working on killing another set of injectors because pw is so long. Im am rich in the section but not quite that rich. At idle though Im pretty decent. Thanks. Though any suggestion would be highly appreciated.

Josh

 

Where is your O2 sensor mounted? Is it too far away from the engine?

Do you have a heated O2 or a normal one? In my Suburban with custom dual exhaust (from the previous owner) they felt compelled to move the O2 sensor to the passenger side pipe about 4 feet from the engine...I was having a problem in colder weather with it not going into closed loop.

Also, is the O2 new? You may consider replacing it...the single wire version is $25 or so.

HTH,

 

ITs a 3 wire so its heated. Its about 1 foot behind the collector on the passenger side pipe. The thing is it really does go lean. No rich smell in the exhaust. O2 isnt really old (less than 1 year) but Im thinkin Im gonna go ahead and change it out.

Josh