Question about VE Tune --AFR error in open and closed loop

[Lakegoat]

E40 SD Tune. I changed pulley size on the Maggie and retuned. I thought I got the primary VE table pretty close. After going to closed loop, the numbers changed a bit. Is this pretty normal?
The open loop table is #1 and the closed loop table is #2. Thanks for comments.

[schpenxel]

Evap system turns back on when you go back to closed loop, so that can (will) affect fueling to some degree

Not unusual at all

[Lakegoat]

Thanks!!

[Ranger6202]

Don't forget that your WB's won't always read exactly the same as your NB's. Few variables are to blame; brand, service life, power source, etc....

[mowton]

Good point Kasey. So to validate your WB vs NB redings, set the tune in closed loop, and log WB value. Run car up to about 20 -30 mph and look at your wb readings. They should be hovering around stich as that is what the NB's are commanding to the PCM. If the WB value is higher, work the offset value in your custom PID down until it is hovering around stoich. If WB is low, then rais the offset value. The good news is you can do this all with the same log in the confines of your home after you logged the data :-)

If you don't have a custom PID (you are using one of the HP Tuners canned WB PID's) and the values are the in line then tht is not your problem. If they are off, then set a User defined WB PID.

Ed M

[Lakegoat]

Good point Kasey. So to validate your WB vs NB redings, set the tune in closed loop, and log WB value. Run car up to about 20 -30 mph and look at your wb readings. They should be hovering around stich as that is what the NB's are commanding to the PCM. If the WB value is higher, work the offset value in your custom PID down until it is hovering around stoich. If WB is low, then rais the offset value. The good news is you can do this all with the same log in the confines of your home after you logged the data :-)

If you don't have a custom PID (you are using one of the HP Tuners canned WB PID's) and the values are the in line then tht is not your problem. If they are off, then set a User defined WB PID.

Ed M

The light is starting to come on now. I replaced my narrowbands a few weeks ago and I guess they are a little different than the old stock ones.
I'm pretty sure the wideband was a couple of tenths low so I will adjust my offset. It didn't register at the time. I will check and make another log and see what difference it makes. Thanks guys.

[Lakegoat]

Yep, Had to do a custom PID for the NTK and adjust the offset. Now the wb and nb read about the same. I had to adjust VE again
Ed, thanks for the info.

[Ranger6202]

One thing to remember, 5% is more than acceptable. You'll find that on any given day you'll dial in the VE or MAF to within 1%, only to find a few days later it's trimming 4-5%. This is totally normal as conditions have changed and will continue to change. A few days more and that 4-5% may now be -3%.

[mowton]

Yep, Had to do a custom PID for the NTK and adjust the offset. Now the wb and nb read about the same. I had to adjust VE again
Ed, thanks for the info.

My pleasure...glad it helped. That was my tip of the month on my ERM Performance Tuning Facebook page last month.....

Ed M

[Lakegoat]

Thanks Ranger, I'm done with the Primary VE. I thought it would be a good idea to give it another look after changing the offset. Boost VE is hard for me to get done. Can't hit many cells on the street--in Mexico.
Ed, I will have to link to your facebook page.

[schpenxel]

Pay attention to what the WB is bouncing between when the NB's are cycling. If they are cycling and the WB is going from say .97 to .99 then I would change the offset by about .02. That'd get them to around .99 to 1.01, which matches up with the NB's IMO.

Either way, it should be close without doing anything...

[Lakegoat]

One of these days I will figure out how to switch this thing to Lambda. Right now, I am stuck in 14.7 land.
Thanks Schpenxel

[mowton]

Lambda is the only way to go..... :-)

Ed M

[schpenxel]

Indeed!

[Lakegoat]

If I can ever get a new readout box from NGK (I broke mine--let the lift down on it) looks like all I have to do is select Lambda with the select button--that is busted. Still works, just can't use the button.