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evo maps not following AFR's or timing maps help please

Practical Reflash Tuning

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Hi Guys,

Just wondering if anybody can shed some light on how to get the standard ecu follow the AFR Map and timing map more accuratley.

Currently i simply data log work out what cell might need changing but both AFR and Timing numbers are way off and no where near what data logs.

What are you logging for load?

Keep in mind what you log as timing will include any additional trims, for example for air temerature.

On a stock Evo when running in open loop the true AFRs never match the AFRMAP values. You will need to rescale the MAF to get them to agree. It gets even further off when you replace the factory airbox/intake with something aftermarket.

Hi hs engineering,

Thankyou for responding i appreciate it i currently log load calc however tried with mod roms 1byte load and 2 byte load still no luck with afr i have used what i lernt in the course on rescalling maf my trims on idle are 0.2 % but maybee i am doing that wrong so if you have any idead on how to do it accurately im all ears,

As for timing i appreciate the trims however on wot my map shows less then what its reading for example i will have 3 in load 240 at 6000 and it will register 7 or 8 and its very sparatic i can do 3 runs on the same road with a pause in between runs and get 3 differnt reading and this is on the whole run/ map so regardless of being on wot or cruise again help on this would be fantastic.

The EVO is a bit of an anomaly unfortunately as the open loop AFR numbers never match the actual measured AFR values even on a 100% stock car. What I tend to do is make sure that my injectors (if you've swapped them) are correctly scaled first - The aim here is to ensure your closed loop trims are as close to zero as feasible. Likewise if you've made changes to the intake system, this may require the MAF calibration to be rescaled to minimise closed loop trims. In my experience though the karman vortex MAF sensor used by Mitsubishi is a little less affected by changes to the intake system than the more common hot-wire style MAF.

In open loop I don't try to chase a MAF calibration that matches the target AFR. If I make an adjustment to the MAF calibration to correct closed loop trims, I'll make it across the board and then accept that my open loop AFR's won't match target. It's still easy to adjust the targets to achieve your actual desired aim AFR though:

Let's assume you want to achieve an AFR of 11.5:1 and the target AFR value at that point in the table is 10.8:1. you've run the car and the measured AFR at the same point on your wideband is 12.0:1. What you need to do is take the measured AFR and divide it by your desired AFR - In this case 12.0/11.5 = 1.043. This means we need to target an AFR that is 4.3% richer than what we're currently targeting to get where we want to go. There's one little trick here though as to target a richer mixture, we need the value in the target AFR table to be smaller (smaller AFR targets are richer). If you use the inverse function on your calculator or alternatively divide 1 by 1.043, this will give you a correction factor to apply to your target AFR table.

In this case 1/1.043 = 0.958. Now we multiply the original AFR target of 10.8 x 0.958 to get the new value - In this case 10.35 will achieve our desired target.

As for the ignition timing, as HS Engineering has suggested, it's possible that the ECU is applying a trim to your ignition value or alternatively the ECU may be interpolating between the high and low octane ignition tables. All of this obviously assumes you're correctly logging a realistic load value - In the Mitsubishi ECU this should be reasonably close to your boost pressure in kPa although it won't be exact - It's a calculated value based on mass airflow rather than a representation of MAP.

Hi Andre,

I thank you for your response, currently I am doing exactally that I am looking at my measured look at my target and place in the difference in the afr table and it works great I was just curious why my map was not following the table that's all,

As for my timing that s another thing al together I will try a few things today in regards to and adders for timing or reductions I will zero everything out and go from there would you suggest this is a good idea??

If I get rid of any trims and zero it all out then adjust my timing then re apply trims that may be required at only certain conditions

I wouldn't recommend zeroing the trims or modifiers. Generally the trim tables are pretty well sorted in the default calibration and carry over quite nicely to your modified calibration. The key really is recognising what trims are affecting the final delivered ignition timing so you can make educated decisions on what changes are necessary.

Oohh i see, thank you for that, once again i appreciate the support given thats what seperates you from the rest well done well worth the money invested. Without sounding like a salesman would u recommend the road tuning course? Will i benefit it for my evo your honest opinion woul be appreciated

You can also log the timing value the ecu uses before any trims are applied. Request ID 33. This allows you to pinpoint where in the map you are operating. I wouldn't use calculated load if I have the option fo 1 byte or 2 byte load as it is far less accurate. If you are interpolating between low and high octane maps you are picking up too much knock so you need to sort that out before you go any further.

Andre, curious why you didn't say just to multiply the map afr x afr wanted/afr you have?

Hi hs engeneering,

How do i log request id 33 where do i input this is it in evoscan? If so how do i add it?

My knock sum is all 0 count so would it still interpolate between maps?

HS Engineering - I understand the calculation I use might seem cumbersome but there is a reason ;)

Right back from our EFI Tuning Fundamentals course we've used the 'Correction Factor = Measured AFR/Desired AFR' which works for a VE or injection time based ECU since increasing VE or injection time will result in a richer mixture. When you're dealing with a target AFR table though you obviously need to reduce the AFR target value to go richer. The reason I use the inverse is so that those who already have learnt the equation can just add the inverse step which is usually pretty simple to remember rather than a whole new equation. Of course the end result is exactly the same and it's personal preference but that is why I took what might seem like a round about approach to the correction.

@Txx33t, the road tuning course is probably not going to be that much value to you with reflashing. Reflashing is quite different to tuning a standalone ECU and in many ways is actually easier to do on the road than tuning a standalone ECU. If you own the Practical Reflashing Tuning course then we are adding a road tuning addition to this course shortly that adapts the techniques shown on the dyno to the road/track.

Hi Andre,

I appreciate your honesty , yes i do own that course and others as well, so if there is any additions ill wait for that.

P.S at least the wife will be happy with that lol

I just moved this thread here Txx33t and deleted your other thread. This is probably the more appropriate place for the information in this thread and prevents double ups.

Hi Andre,

All good mate, i sent a message when i was watching the course then i had an email to set it up in the forum so i did hahah

I do apologize.

Mate its Sunday get off the forums and spend some time with the fam.

I appreciate all you help and input fantastic support.

Hello Andre,

in a few posts back you say :

"All of this obviously assumes you're correctly logging a realistic load value - In the Mitsubishi ECU this should be reasonably close to your boost pressure in kPa although it won't be exact - It's a calculated value based on mass airflow rather than a representation of MAP."

but how is load being calculated? what is the mechanism behind it?

In the Mitshubishi Evo X Ecu the timing and fuel maps are load based right?. So if someone needs to do an adjustment to these tables he must consider the values in a table that in one axis is load and in the other axis are RPMs, derived from a log.

But how does the ECU calculates that load?



Hi, you can log the load value. But you have to modify your ROM for what they call mode 23. Just google it you will find instructions on how to set it up.


I didn't see your question before. In EvoScan, right click anywhere in the logged parameters window. A box will come up, click on edit data items, another box will come up with all the logged data items. At the bottom left corner is a button called add new item. Click on that and enter your parameter. You can use the same values as the other timing you are logging. Give this a different name of course and set the request ID to 33.

Thank you HS Engineering for your reply,

I am logging with Rax fast logging and i see load as big as 370. My MAF and MAP tables are rescaled to match the greater airflow that my Evo X sees. My car has larger turbocharger (GTX3076r), ID 1300cc injectors, 3.5inch intake,etc.

I was trying to understand how is load being calculated. What is the mechanism in the ECU.