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VCT Tuning with Factory ECUs

Variable Cam Control Tuning

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Hi I was wondering if there are any plans on adding a worked example for VCT tuning with a factory ECU that can't be live tuned? Or if anyone had any tips on this process. I understand that the WOT ramp run process is the same but are there any tips or tricks to optimising the cam timing at lower points in the rev range seeing as we can't just hold the car at steady state and adjust the map on the fly?

Thank you.

I don't think there is much to be gained. If someone with a standalone tuned a different map using the same intake / cam / exhaust as you have, then I would consider using that map in place of the OEM. Otherwise, you would have to develop a test plan to try different maps, and measure the results on a dyno. Unless the exhaust is significantly changed, I don't expect you will find much to be gained there.

Well to add more context, I'm playing with the Evo X and Ralliart platforms that are very limited in terms of ECU options due to the way the gearbox is integrated (gearbox its self needs to see MAF values, etc).

So its not uncommon to do turbo and cam upgrades while still retaining the factory ECU for this reason. So I believe there are good gains to be had, such as faster spool, etc. Just how do I go about getting it?

Like all tuning -- make a change and measure the result. For CAM timing, any change that causes the Lambda/AFR to go leaner means there is more air being processed, and so likely you can make more power if you will add the correct amount of fuel.

For your situation -- make a change, and measure the spool time if that is your goal.

Same with ignition timing, if you need to pull some that would suggest better cylinder filling.

Thanks for the input guys. I understand that it's all pretty much trail and error, was just wondering if there was a way to speed up the process seeing as I would have to go though the whole process of log on dyno > add 10 degrees to map > turn car off > flash in new map > turn on car > let everything stabilise > log again, for pretty much every RPM column which I'm sure you guys know is a lot of dyno time.

Good points with the AFR and ignition timing tho, I never really looked at the bigger picture like that. Working on that logic I might be able to get it somewhat close on the street and then just try and get it perfect on the dyno.

I would suggest you consider just trying flat maps (ie, all sites at 5 deg, all at 10 deg, etc). Then on a load bearing dyno, log the torque output along with the load and Lambda at a single RPM. Then change the RPM and repeat (note you don't need to re-flash except to change the cam table).

You can process this data into a spreadsheet for each RPM. Layout a table with a column for each cam angle, and a row for each load. Enter the torque (or Lambda) at each condition.

It will be easy to find the the cam angle that produced the maximum torque (or leanest lambda) for each load point. That is what you use to build your target cam table. Adjust the fuel table using the lambda values from the same conditions.

Now with that cam table decided, you can better tune the fuel map (again, by repeating the fixed RPM runs, and making a single flash adjustment after doing the whole table). Repeat a couple of times, until the fueling changes are 1-2% or less.

Now you can try to find the MBT ignition timing...

Yeah damn. I really appreciate the input David. I'm pretty new to this, as you can probably tell and your advice will go I long way. Thank you.

I personally never even thought about using a spreadsheet.

search for "tephra" or "tephramod" he developed a modified factory rom for evo 9 / 10 and increased the feature set of what the ecu was able to do (including live tuning / antilag / map sensor instead of maf sensor stuff) - there are also tonnes of factory evo 9 roms (probably evo 10 as well if you look) - ralliart roms seem to have good cam angle / timing settings based on more power rather than better economy / emissions etc

in an evo9 a friend of mine had we were hacking around and imported the ralliart cam angle map into the factory rom among other things and that was a difference of night and day really - more like a smack in the back of the seat with a baseball bat when you stamp on the throttle instead of the normal turbo spool up that was more gentle by comparison.

You can get very good results with the factory evo ecu's.

hacking required to make it work tho.... your going to have to be happy with hex editors and reflashing the ecu's and copying blocks of data around to retain the factory immobilizer etc - and if the car goes in to mitsi for a service itll throw an error with their diags and they will reflash it back to stock again as my friend found one time lol