Modded Mustang Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
60 Posts
Discussion Starter #1
I currently have an off-road h-pipe and I was wondering if I use my hand held tuner to turn off the o2 sensors would this affect the tune that is on the kb chip that was supplied with the supercharger? The other question I have is I've read that the optimal a/f ration should be somewhere around 11.2-11.7. What is the norm while at idle, because mines is jumping all over the place in between 14-17. Even when driving(taking it easy not shifting above 2k before I get a dynotune) it was still acting crazy. Would the placement of the a/f ratio sensor or off road h pipe have an affect on this?
 

·
I <3 Boost
Joined
·
7,687 Posts
throw the h on and leave it be till you get it dyno tuned. all itll do is throw on the cel. it wont make it run any different.
 

·
Registered
Joined
·
2,936 Posts
I currently have an off-road h-pipe and I was wondering if I use my hand held tuner to turn off the o2 sensors would this affect the tune that is on the kb chip that was supplied with the supercharger? The other question I have is I've read that the optimal a/f ration should be somewhere around 11.2-11.7. What is the norm while at idle, because mines is jumping all over the place in between 14-17. Even when driving(taking it easy not shifting above 2k before I get a dynotune) it was still acting crazy. Would the placement of the a/f ratio sensor or off road h pipe have an affect on this?
If the KB tune is literally a "chip", connected to the J3 jumper on the PCM then there is likely nothing you can do with your handheld that will change anything in the tune.

As to AFR, you need to understand that there are two basic operating modes, closed loop and open loop.

In closed loop mode (I.e. "most of the time") the PCM accepts input from the front O2 sensors and constantly modifies the injector pulse width to maintain an average AFR of 14.7:1 (the stoichiometric mix). The narrowband sensors can only tell the PCM that the mix is lean or rich, so it (the PCM) continuously changes the pulse width as needed to keep the average of the lean/rich excursions at 14.7:1.

In open loop mode (65% throttle to WOT) the PCM ignores the feedback from the O2 sensors (they cannot respond fast or accurately enough) and uses a combination of fixed and learned data to try to hit the target AFR defined in the tune--11.2 to 11.7:1 being a usual target for f/i applications.

What sort of AFR meter are you using? If it's a "light show" meter connected to one of the stock narrowband sensors then what you describe ("all over the place in between 14-17") is normal. A wide band system would still vary in closed loop, but not as wildly; typically between 14.5 to 14.9:1...
 

·
Registered
Joined
·
60 Posts
Discussion Starter #5
If the KB tune is literally a "chip", connected to the J3 jumper on the PCM then there is likely nothing you can do with your handheld that will change anything in the tune.

As to AFR, you need to understand that there are two basic operating modes, closed loop and open loop.

In closed loop mode (I.e. "most of the time") the PCM accepts input from the front O2 sensors and constantly modifies the injector pulse width to maintain an average AFR of 14.7:1 (the stoichiometric mix). The narrowband sensors can only tell the PCM that the mix is lean or rich, so it (the PCM) continuously changes the pulse width as needed to keep the average of the lean/rich excursions at 14.7:1.

In open loop mode (65% throttle to WOT) the PCM ignores the feedback from the O2 sensors (they cannot respond fast or accurately enough) and uses a combination of fixed and learned data to try to hit the target AFR defined in the tune--11.2 to 11.7:1 being a usual target for f/i applications.

What sort of AFR meter are you using? If it's a "light show" meter connected to one of the stock narrowband sensors then what you describe ("all over the place in between 14-17") is normal. A wide band system would still vary in closed loop, but not as wildly; typically between 14.5 to 14.9:1...
I'm using a Glowshift 10 series Wideband Air/Fuel Gauge. I will try and post a video tomorrow afternoon.
 

·
Registered
Joined
·
2,936 Posts
I'm using a Glowshift 10 series Wideband Air/Fuel Gauge. I will try and post a video tomorrow afternoon.
Then 14-17:1 is a bit much in closed loop mode, typically one would see 14.2 to 15.2 max...
 

·
Registered
Joined
·
4,531 Posts
Then 14-17:1 is a bit much in closed loop mode, typically one would see 14.2 to 15.2 max...
agreed.. anything over 15.5 is a lil too lean. at idle the a/f will jump a little but when you take of or are cruising it shouldnt jump near as much.

I would take it to get dyno tuned and lose the KB Chip. I have seen a lot of guys jsut run the KB chip and last for ever but i still dont trust it, and this is a good example.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #8
Issue resolved for now until I get a dynotune next month. Yesterday I was driving around the komplex to see if the A/F ratio would still jump all over the place and I noticed that my battery indicator was really low so I kame back home and started troubleshooting because the batter is practically new(2 months). So, I narrowed the issue to the something in between the alternator(new) and battery(new)....after tracing the wires from the fuse box....I noticed that the little gray cable was not connected so I connected it and power issue resolved....so I did some highway driving at it was in between 14.1-15.0 while using throttle...it only went above that when I let off the throttle...but then came right back down to it. So, I got on it a little bit just to hit boost and while in boost it went down to around 11. But I'm still gonna take it easy til I get a tune. Thanks for all your help.....
 
1 - 8 of 8 Posts
Top