calibrating AFR

[LETZRIDE]

Does anyone know how to make a custom PID so that you can log what your actual AFR is on your gauge (for me AEM) versus what it actually shows in hp tuners?

For those of you who havent noticed, the two are actually off and mine doesn't seem to be linear so I can't use just the offset method it seems.

This basically makes this a two part question

1st being how to log to get the info I need
2nd being, how can I use the list function to configure the wideband instead of the linear function?

[thebeewantsboost]

Re: calibrating AFR

what wideband are you using?

[LETZRIDE]

Re: calibrating AFR

AEM- the pre determined one is wrong. I know how to change/modify that, I found the equations. I have my volts set to .625 and the offset is the stock 10, I moved it up to 10.2 and that seems to get rid of most of teh error down low, but at WOT it is off by atleast .4-.5

I know there is a way to make a custom PID to see exactly how much it is off, and then a way to use the list function rather than the linear function to get the wideband to match perfectly, which is what I want. Just all the old threads I found that had info, had the info in pictures and the pictures now no longer exist...

[thebeewantsboost]

Re: calibrating AFR

oh, hmm, i have no idea. i have the same wideband. and i dialed it in on hp tuners at idle and never really questioned it at wot. let me know what you find out.

[Blizzard242]

Re: calibrating AFR

What I did was let the car idle and warm up a minute, then turn it off. The AFR would slowly rise but it was much easier to see the difference between my gauge and HP tuners to figure out the offset. I got into like 3-4 decimal points. It was still acting funny though, I blame that on exhaust leaks.

[LETZRIDE]

Re: calibrating AFR

What I did was let the car idle and warm up a minute, then turn it off. The AFR would slowly rise but it was much easier to see the difference between my gauge and HP tuners to figure out the offset. I got into like 3-4 decimal points. It was still acting funny though, I blame that on exhaust leaks.

The problem with that is you are now atleast 3% off ontop of however much your hp tuners program is telling you... Since this is usually up to 5% you're now up to 8% off which can be more than a full point...

[Blizzard242]

Re: calibrating AFR

The problem with that is you are now atleast 3% off ontop of however much your hp tuners program is telling you... Since this is usually up to 5% you're now up to 8% off which can be more than a full point...

How so? I'm not arguiing, I'm curious if you can explain it in a way that makes sense or if you have a link to some info?

[LETZRIDE]

Re: calibrating AFR

How so? I'm not arguiing, I'm curious if you can explain it in a way that makes sense or if you have a link to some info?

Well I dunno, I could be wrong but it's just my thinking... if you scan, you're probably showing 3-5% error correct? Because no one has a perfectly calibrated maf in every cell for more than a few days?

so taking best case (if your tune is good) is 3% so lets just look at if you were at stoich during cruise which is 14.7afr...3% error means that your tune could fluctuate either rich or lean by .4 so you will probably bounce between 14.3 and 15.1

Now, if what your hp tuners reads is also off from what your actual gauge is seeing by another .3-.4 points, that means you could be seeing 14.0-15.5 just during stoich commanding conditions alone. The thing with this is though, is you will think it is ok because hp tuners will show it is only at 14.3-14.4ish so you'll say the tune is "close enough" when in reality it is actually another 3-5% off of what your showing

Does that make sense? Not sure how to really explain it... but its just my thinking, I could be wrong..

[Blizzard242]

Re: calibrating AFR

How does this relate to my AFR reading in HP tuners compared to my gauge? I understand what you're saying but I don't think we hit any points on gauge to HP tuners accuracy when trying to calibrate just after shutting the car off. We're just trying to make HP tuners scan match the gauge right?

[LETZRIDE]

Re: calibrating AFR

I don't follow your question?

Your hp tuners readings have to match your wideband readings, any error in those readings translate to errors while correcting your MAF calibration.

Lets say Hp tuners says your car has a current and steady 14.7 afr but your wideband is actually showing 15.2 afr (lets just say) When you scan your maf error it will show 0% telling the pcm that the MAF is perfectly calibrated when you write your tune when in reality it isnt. Now everytime you make a calibration change whatever your error for the MAF shows, has the error difference between your wideband and what Hp tuners is reading added to it

[Blizzard242]

Re: calibrating AFR

Ok, you know how steady your AFR gets on your gauge after you turn the motor off? It basically sits for a few then slowly leans out. Well, HP tuners will still scan during that time so it's easy to compare the gauge to what you have your AFR calibrated at in HP tuners. Rather than trying to look at a bouncing number, it's slow and smooth and easy to adjust.

Another idea would be to (ideally have a passenger) stare at your gauge while doing a WOT run and just remember the lowest number then compare what your scan says later and adjust from there. I'm gonna try that one actually, seems like a better idea than shutting the motor down since that's the area I really want my tune to be accurate.

In my car, around idle, my gauge doesn't sit very still so I've tried to find other areas where the gauge is easier to read.

[LETZRIDE]

Re: calibrating AFR

I see what your saying...for me when I shut the car off my wideband is steady, my hp tuners fluctuates .3-.4 and continues to bounce around.

Im concerned also that how much I am off at WOT is different from what I am off at part throttle, and I'd like everything to match, so instead of adjusting using the linear offset, Id rather use the string/line of numbers to adjust.

There is a PID that you can create that will show you the difference of how much you are off wideband vs hp tuners- that's what I would like to find out how to create because that takes all the guess work out and insures accuracy, the problem is, the one thread I found at hp tuners showing how to do it, all the pictures are "X's" because its an old thread

[Blizzard242]

Re: calibrating AFR

Ohhh I see now. That would be nice but sounds like a hard PID to get working, I can't even wrap my mind around how it would even work.