TheSamba.com :: View topic - PLX DM-6 AFR Wideband

Mon Aug 01, 2016 2:14 pm

About to "pull the trigger" on one of these:
http://www.plxdevices.com/Wideband-O2-Touch-Screen-Multi-Guage-p/897346002719.htm

My understanding is that the widely held standard is a AFR of 14.7 is the ideal number at idle. What, however, should it be at WOT? At cruise? At slight acceleration? At transition, for a NA, carbed T1 engine?

Mon Aug 01, 2016 2:31 pm

I run the same wideband on my cb efi. 13.5 is what they loaded in for the initial tune at idle. My car likes a bit richer at idle though. You do not want 14.7. My understanding that while that is perfect combustion, you can burn up a motor running that.

Run a search on fuel maps in google images and there are some conclusions you can draw from them.

Mon Aug 01, 2016 2:38 pm

Look at the wideband/tuning thread. Pretty much everything you need to know is in there, just have to do a little reading.

Mon Aug 01, 2016 4:24 pm

Not every motor is the same, your engine may "want" 14:1 at idle, or it might "want" 13:1 at idle. You have to figure out what it needs at given loads and tune acordingly. My 2387 idles the best at low 13's, my buddies 2175 idles the best at high 14's

Mon Aug 01, 2016 4:35 pm

Good starting points: idle 13.5-14.5, WOT 12.5, lean cruise 15.0-16.0. As mentioned, beyond that it's really what the engine likes. Plus you're going to be limited on overall AFR control with just carbs.

Mon Aug 01, 2016 8:51 pm

I also run the PLX DM-6 gauge with AFR sensor.
I am really happy with it since I can add other sensors if I want and it fits in my dash.
I have the Gen 3 since the Gen 4 wasn't out yet.
My engine likes 12.8:1 at idle and I have it 15.1:1 at light cruise up to 3500 rpm.
Boost is 12.5:1 and richer depending on how much.

Tue Aug 02, 2016 12:30 pm

Re. using AFR gauge to set-up IDA's properly... I just read a thread over at STF that is a great read if you, like me, are unfamiliar of the particular "quirks" of getting IDA's to run nicely on the street:
http://www.shoptalkforums.com/viewtopic.php?f=15&t=148633

Wed Aug 24, 2016 12:55 pm

Just got an email from PLX that they are introducing an app and "pigtail" transmitter that'll plug into their Wideband SM-AFR. Puts the multi gauge capabilities in your hand, on your device.

May be interest to some.

http://www.plxdevices.com/ProductDetails.asp?ProductCode=897346002931

Fri Aug 26, 2016 8:25 am

I liked my DM6 dispaly until I had a short from 12 volts to one of the power cables on the gauge. To save money and heat generation in the display they regulate the 12 volt power in the red box near the sensor and feed 7.5 volts for the OLED and 3.3 volts for the processor in the daah display.
So if there is a short then the display fails permanently.
So now I am making my own display ..

Idle 14.7:1 WOT about 12:1 Light load slightly downhill at 60-65mph about 16:1
And it shows what a mess a carburettor makes of adjusting to load and providing mixture to match . A tap on the throttle and it settles down with a different AFR and the same RPM.

Fri Aug 26, 2016 9:07 am

I burned out my first DM6 doing the exact same thing. They gave me an idiots discount on the second one....