Closed loop wideband is pretty cool. I've seen it first hand on a Megasquirt with a after market turbo Miata, and read about a lot of other success stories. In addition to quite a bit of hacking to the ECU code you need to look at the analog input as well. We can be programmed for a 0-1V linear wideband output, and other linear wideband outputs could be scaled with an op amp, but the analog input itself might have some physical filtering.

Stoich is actually a singularity on the sensor, the chemistry actually changes on each side of stoich. To stop from oscillating out of control, most systems that read the sensor implement some variant of a PID control loop. Sometimes an external filter is used to keep the software implementation simpler.

Even if this is the case, you might still be able to avoid physically modifying the ECU, provided you can find an alternate analog input you can re-purpose. For example, on some Subarus users re-use an analog input from the fuel system to log analog wideband measurements.

-jjf

 

SO can I clarify, should the Swap X-Y have a check or not? I am fighting an initial warm up lean condition in 1st and second gear. Upon acceleration in 1st gear when the car is first started it will stumble and the WB will read 16-17.3 around 1800 - 2400 rpm.

If I leave the Swap X-Y checked this follows the 60-80-100 load sites and where the AFR is highest in the map. Picture is below:

 

Can the car be made to run only in open loop, no matter what, and if so would it be detrimental to the car for any reason?

 

I have my car running in open loop only, at the moment. I changed all the open loop load and rpm cells to 0. I'm using maft pro for partial throttle and WOT AFR tracking. I've set my idle rpm to 1000rpm and the idle AFR to 16.5:1. Part throttle and low load is 15.5:1 and WOT is 11.5:1. Transition from partial to WOT is smooth and fuel economy is increased.

 

You are using AFR Tracking though, and that is similar to what closed loop does, so you don't really need it.

Yes, you can run the car in open loop, the easiest way is to set the coolant temp for closed loop operation higher than the engine temp could ever reach.

Here's the caveat, you will spend alot of time tuning the maps to get your AFR's into your target, if your target is a bit leaner for better economy, then the above post illustrates another valid way to have some sort of closed loop operation. However on the stock car, your target would be about 14.7 in closed loop regions, the cool thing is once you get all of that worked out, if you re-enable closed loop operation, you'll have almost perfect fuel trims. (this is actually one tuning method for part throttle and closed loop drivability)

 

Be aware that disabling closed loop operation means that there may be some OBD-II tests that will never complete, so inspection might be a problem. Additionally you will no longer have any compensation for changes in weather or load, which are outside the compensation range for the MAF sensor. You would also get some poor drivability with the a/c on as you would have to tune for the additional load also.

Like i said earlier, keeping the car in open loop perminently isn't a great idea, but its a good way to tune the car properly.

 

Any idea on the Swap X-Y issue?

 

thanks MJ.