is there a patch out there that enable you to control closed loop a/f ratio. because my car runs 15.9 sometimes.

 

Using a narrowband it would have to periodically test the trim to stoich and then run open loop with an offset? Or are you talking full range wideband closed loop?

 

my wideband shows 15.9, it just seems way to high. I guess there is always the option to adjust open loop table so the car is never in closed loop but i rather not do that.

 

When the wideband shows 15.9 is the narrowband O2 oscillating or is it close to 0V?

 

I have all of my open loop load settings at 10.0 since switching back to e85 to try to get a little better MPG's and my oxygen feedback trim is always at 100 with evoscan and all 3 fuel trims never change anymore
ed

 

lemonhead, JohnBradly has some full time "open loop tps/ load" maps shown in one of the economy/ecuflash threads.

I have been driving with that feature for several weeks and think its great.

 

Lemmonhead, what WB are you using? The narrowband simulated output of a few WB's allows you to adjust the stoich switching point.

First thing I will mention is if your NB O2 sensor is working fine, yet your WB is reading lean, that indicates a leak between the NB O2 sensor and the WB O2 sensor, generally. Running in closed loop is by FAR the best way to make use of the computer controlled fuel management. Try to optimize closed loop operation as much as possible. Dumping the closed loop setup in favor of open loop is generally a crutch to poor tuning skills and user frustration.

Running E85 wont be more fuel efficient with our engine than running gasoline (even with up to 20% ethanol mix). Unless you were running higher compression pistons, adjusting the stoich switching point to something a little leaner in closed loop with gasoline (15.2-16.0 with EGT monitoring if possible) will yield the best fuel economy.

Running at 14.7:1 my car did about 20-22MPG on gasoline with up to 10% ethanol. Running at 15.5:1 (with 272 cams) my gas mileage increased to roughly 23-25MPG. This was without any change to ignition timing as well. If you take the time to get the closed loop system working optimally with a good closed loop timing map, you can get some very fuel efficient cruising MPG's. I just got my car back on the road but I will be trying to dial in my cruising areas in my timing map this month to see how well I can get the results to be.

 

I will take a look, thanks

 

I got the AEM Uego

 

Hmm, not sure if the AEM has an adjustable NB simulated output. I know the Innovate and Zeitronix WB's do for certain though. Not that it helps you any,lol.

 

I searched and found that thread, ya it would be cool if my wb had a 02 simulator, cause I would like to get it down to 15.5:1 instead of 15.9. That seems a bit to high for my liking. my logs show that I get that partial throttle knock when its 15.9 cruising.

 

Can you explain further how this is done? What table are you using to control the target afr in closed loop?

The threads that I have read all deal with lowering the closed loop to open loop switching point using either load or throttle position.

 

I'm not trying to promote open loop use, I just find its one to one relationship easier to understand.


with the open loop engaged you can dial in whatever afr you want. you only need a wideband to keep track of your afr. there is no need for the analog outs that switching uses.
you simply dial in the afr you want to run at using the fuel map.

Now, Jack OAT, may be right, but with open loop you are replacing the trims feedback,& the sensors output with your desired inputs. The net result in either case could be the same.

Since using open loop is set in stone, you do need to keep an eye on your afr. If the injectors loose 10 % over time you will loose 10 %. With closed loop the feed back would adjust the flow to compensate. That ability is the only reason (I can think of) the manufactures use closed loop.

 

Its adjusted in the WB software, not the ECU. Your using the simulated narrowbend output to trick the ECU into switching between lean and rich at a point which you choose. Compared to the stock O2 sensor that is set to only switch at 1.0 lamda (14.7:1 for gas)

 

what if your wb sensor goes bad and cant trick the ECU what would happen? would you go really lean?