AFR Error Math???

[South Lakes Speed Shop]

Hey guys, need a little help setting this up......


Not sure what the hell is going on with the math but I cant get my LM-2 to give me a proper percentage that makes sense


Using this math function given I am getting ridiculous percentages (as seen behind) for AFR error, this is definitely not right as the commanded AFR was around 11.3 and the AFR read by the Innovate LM-2 was 12-13.....as verified by my nose because it smelled hella rich!


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[07GTS]

your math is not right keep it the same as the default one without the extra u put in there

[South Lakes Speed Shop]

I tried that and get stupid numbers too........


Losing the will to live with this one, so my AFR math should be correct according to this current one but if you look at the logged AFR at around 12:1 and commanded then look at the % error in the graph something is definitely up as I'm not 40% rich if I'm running at 12:1 AFR

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[South Lakes Speed Shop]

C'mon surely someone has to have an idea?

Here's a better example


1011 RPM

Commanded AFR = 12.46
WB AFR = 13.20

That gives an error ratio of 5.9% lean vs commanded at idle


Now why is it showing 45.25% ?

My user math is as follows

(([LM-2 Transform] - [Commanded AFR]) / [Commanded AFR]) * 100 = AFR Error %

No doubt I'm missing a simple trick here but I have no idea what, this is a steep learning curve for me so any help would be appreciated as I've probably just over looked something. But as you can see from the graph read out the AFR transform from LM-2 is showing correctly and the same in the recorded PID so I have no idea why I cant get the correct percentage

I have also tried it using the generic sensor rather than the transformed readout and it comes back with the same stupid numbers



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[5FDP]

I never ran into this issue because I didn't have to create a custom wideband graph for my AEM wideband. I just click the premade one that is already in there and it worked perfect.

[South Lakes Speed Shop]

I never ran into this issue because I didn't have to create a custom wideband graph for my AEM wideband. I just click the premade one that is already in there and it worked perfect.

It is getting to the point where I'm just going to buy an AEM and in fact I may well do........

The LM-2 looked good which was why I went with it but in hindsight I probably should have gone AEM, it is loaded in via serial direct to laptop and scanner so there should be no issue with the signal (and isn't going off the readout on gauge vs recorded AFR)

Just makes it impossible to tune accurately without it working

[dhoagland]

Is it reading correctly in your channels?
Just the graph is messed up?

Can you post the actual log?

[5FDP]

Is there nothing there in the MATHS - predefined that work?

[South Lakes Speed Shop]

Is it reading correctly in your channels?
Just the graph is messed up?

Can you post the actual log?

Yes, just the graph seems to be messed up.

Someone on one of the facebook groups suggested it may be trying to output in EQ still even though its a transformed function (thus giving the wacky numbers)

Log attached



Reduced spark C5 900rpm idle.hpl

[South Lakes Speed Shop]

Is there nothing there in the MATHS - predefined that work?

Unfortunately not, I tried all the user math before starting to make my own

[dhoagland]

I think I might be on to something

Can you send your tune file so I can have the correct table values?

[South Lakes Speed Shop]

I think I might be on to something

Can you send your tune file so I can have the correct table values?

Sure, I'll attach it here


For reference engine is on stock injectors, but is a 383 with ported heads, Holley fabricated sniper intake and an MS3 cam






C5 - It runs! Reduced spark.hpt

[dhoagland]

Try this graph
I'm showing you about 6% lean.

NOTE
This is for your secondary VE table. As I understand that is referenced when you have the MAF failed.
You can get the trend and paste into your primary VE if you decide to re-enable your MAF

This is only taking the info from the "Transformed" wideband
It assumes that is correct

[5FDP]

Side remark here, get bigger injectors before you get too deep. You will be out of fuel in no time with those small things.

[South Lakes Speed Shop]

Side remark here, get bigger injectors before you get too deep. You will be out of fuel in no time with those small things.

Thanks, I will modify the secondary although given the AFR readout that still doesn't make sense that it is showing the primary as 40% rich

I was also under the impression that primary was tuneable whilst MAF is failed


As to injectors I am aware they will be at their limit but if need be I will put an RPM limit on the engine to stop it going past where they can fuel and upgrade in the future. The 4l60e is the weak link at this point so don't want to be revving to the moon, 6000rpm redline with 5000rpm shift point should keep both in a safe limit


I did bump up the secondary VE by 15% earlier today but haven't flashed it on yet, if it is showing at 7% lean then that should theoretically fix that graph and make it rich when I retry.

My main concern is still the primary though

[5FDP]

The primary VE is not used in speed density on this OS, only the secondary VE table. That's why there is two table.

The primary VE table is only used when NOT in speed density along with the MAF.

This is an early OS you are using. Computers after the year 2000 removed the secondary table and only have one VE table that is used all the time.

[dhoagland]

Here is your Primary Graph layout
It shows the same readings just missing some cells

I could be wrong on the Primary vs Secondary
That might be another question to post in the Gen 3 Section

Anyway
You now have 2 graphs for each of your VE tables. I'm sure there is no harm adjusting both

[dhoagland]

The primary VE is not used in speed density on this OS, only the secondary VE table. That's why there is two table.

The primary VE table is only used when NOT in speed density along with the MAF.

This is an early OS you are using. Computers after the year 2000 removed the secondary table and only have one VE table that is used all the time.

Thanks for the Clarification!!

[Russ K]

Delete the LM2 Eq from your Channels. As your AFR is being averaged between the LM2 AFR & the LM2 Eq.

Then just use the default AFR Error in your Graphs.

Russ Kemp

[dhoagland]

Delete the LM2 Eq from your Channels. As your AFR is being averaged between the LM2 AFR & the LM2 Eq.

Then just use the default AFR Error in your Graphs.

Russ Kemp

Good to know