Big cams and VE tuning

[Redline Motorsports]

I am just starting to tune a F-body with a 408 ProCharged motor. The car has a huge cam and is happy just idling at 1000. It is very interesting to see that the motor idles at 70 KPA which explains why the thing doesn't like running at all on a stock VE table! Just to keep the car running I took 40% of fuel away as the VE values at 70-75 KPA are quite large! It looks like a challenging tune as at cruise speeds its 40-50 KPA and then of course over 80 KPA for WOT and boost.

Because I was having problems with WB and EFI cooperating, I was just loading the motor on the dyno and calculating the math to make bulk changes to the VE. Its weird seeing green cells that far into the table! Anyone else got any pointers on the bag cam VE tuning?

Howard

[TAQuickness]

WB and patience. sounds like one hell of an app

[Redline Motorsports]

What I could really use is the answer to why the FS is not properly reading the WB output.....

[69camaro5speed]

with big cams you get blow down at low speeds it will cool off the o2 and say lean when its really to rich makes it tricky to tune some times you have to tune it off how it sounds and acts at low speeds little to rich it will sound really chopy little lean will be surgy and not very responsive some times you have to tunes off how it feels witch can be tricky i have tune so many motors its not bad for me. exhaust helps if its realy camed big (duration and over lap ) if you put a o2 in the header tub 18 inches from the valve it will have enoff heat to become active but with a procharger it may have to much at wot and damage the 02 i dyno motors all the time with 8 02s in headers with cams rollers even 285@.050 duration they are active at low speeds. a o2s are tricky with big cam motors if you live buy them you can dye buy them look at fuel pressure, injector duty cycle, load that you have on the motor,air temp. ( mechanical numbers ) if its realy bad you will have to run it in open loop when your done other wise when the 02s start getting false info it will try to curect wrong. hope this helps

[SSpdDmon]

What kind of wideband are you using and how is it wired up?

[Redline Motorsports]

For starters I don't plan on reintroducing the O2's. The car is for limited street use and track time so I am not going to go nuts tuning it for "daily" usage.

I am using a Autronics WB. It is tied into the dyno and reports on the screen during pulls. I made a harness to tap off the 0-5 volt output and sent it to the EXT.AD1 input of FS. The voltage output is correct as I have worked the formula back. The FS is seeing the correct voltage but no showing the correct AFR on the dashboard. It has been brought to my attention that the dashboard display cannot keep up with the input readings from the WB. I guess if the volatge is correct and the match works, the MAP for recording the BEN factor should be ok regardless of what the dashboard reads.

Howard

[SSpdDmon]

The AFR that shows in FS is a calculated PID. If the number is wrong but the voltage is right, then the formula is wrong.

What is 0mV and 5mV supposed to be with that WBO2?

What does your calc PID look like?

[Redline Motorsports]

I agree on what you are saying.

Here's what I have determined;

I have witnessed the readout on the Autronics unit display a given AFR reading. At that time I have checked the output voltage on the 0-5 volt output from the WB. It is correct using the pid in the generic sae folder. The formula is ({EXT.AD1*4})+10.

I then hooked the 0-5 volt output to the FS in which it sill is reading the correct voltage. Watching the logged voltage on FS it matches the voltage measured from the 0-5 volt output. This is on the dashboard. Is there an issue with the way the dashboard see's these values?

I was told to check the data tab info and also build the MAP for BEN and look at the average.

If I go and alter the pid in the generic folder, is that an acceptable way to readjust the readings? everything seems to be correct!

[SSpdDmon]

I agree on what you are saying.

Here's what I have determined;

I have witnessed the readout on the Autronics unit display a given AFR reading. At that time I have checked the output voltage on the 0-5 volt output from the WB. It is correct using the pid in the generic sae folder. The formula is ({EXT.AD1*4})+10.

10:1~30:1 seems like an odd range for a wideband, but that's what my sae_generic.txt file says too. Still doesn't mean it's right. I'd check the documentation and see if the calibration of your WB out of the box is set to detect 10:1~30:1 on a 0-5v scale from the factory.

I then hooked the 0-5 volt output to the FS in which it sill is reading the correct voltage. Watching the logged voltage on FS, it matches the voltage measured from the 0-5 volt output. This is on the dashboard. Is there an issue with the way the dashboard see's these values?

I've yet to notice any issue with the dashboard having trouble reading a number from my LC1. Voltage is voltage plus or minus any ground offset you may be seeing.

I was told to check the data tab info and also build the MAP for BEN and look at the average.

If you're using the most recent version of EFILive, there should already be a BEN calc for an Autronic WB. Are you using these?

If I go and alter the pid in the generic folder, is that an acceptable way to readjust the readings? everything seems to be correct!

I've made adjustments to my sae_generic.txt file to account for ground offset in my WB. As long as you have everything in place and your formulas are right, I think it's ok to make changes here.


I still think it's odd you can't see below a 10:1 AFR with that WB...

[Redline Motorsports]

I checked the instructions off of Autronics site in which they indicate the voltage vs. AFR range. This was also confirmed by measuring the voltage output and seeing the AFR. When those values are placed in the pid formula it all works.

It is a wide spread as you only really use .00 to 1.6 volts of the 0-5 volt signal.

I am using the most current version as well as the provided pid on the Autronics unit.

If I make changes to the generic pid cals is it as easy as just making the change and saving the file? Is that how the system works by going back to that folder for its calculations?

[SSpdDmon]

As far as I know, yes. I opened the text file from the installed directory. If you can't find it, do a Windows Search (start menu) for "sae_generic.txt" and it will find it. Then, Ctrl+F search in the document for Autronic. You'll see the equation it uses to calculate AFR. This also feeds the BEN I believe. Make your changes, save the file and close it.

Thinking about it some more, I wonder if your problem is resolution. Since there's such a wide range on your WBO2 and you said yourself you don't often see numbers over 1.6v, it has to affect the numbers you see. I take it you can't reprogram the output so that 0v=9:1 and 5v=18:1 or something along those lines? If you can, that would greatly improve your resolution and a .5v to .6v change wouldn't be such a huge swing.

[Redline Motorsports]

As far as I know, yes. I opened the text file from the installed directory. If you can't find it, do a Windows Search (start menu) for "sae_generic.txt" and it will find it. Then, Ctrl+F search in the document for Autronic. You'll see the equation it uses to calculate AFR. This also feeds the BEN I believe. Make your changes, save the file and close it.

Thinking about it some more, I wonder if your problem is resolution. Since there's such a wide range on your WBO2 and you said yourself you don't often see numbers over 1.6v, it has to affect the numbers you see. I take it you can't reprogram the output so that 0v=9:1 and 5v=18:1 or something along those lines? If you can, that would greatly improve your resolution and a .5v to .6v change wouldn't be such a huge swing.

I think you are right about the resolution. Cramming the entire reasonable fuel curve in from .4-1.6 volts is nuts! I am trying to figure out how to stretch it out. In the mean time I went back to the LM1 which seems OK.