RomRaider

Hello Everyone I am an experienced Subaru technician attempting to teach my self how to tune. I am starting to practice on a build I recently finished and have a a couple of questions as well as I am hoping to get a base map that has a good starting point for me to work off of. So let start with the car:

02 Subaru WRX with a JDM EJ205 with AVSC and a td04 tubro. Currently mods on the car are: K&N typhoon intake, grimmspeed 3 port boost controller, grimmspeed catless up pipe, grimmspeed devorced downpipe with high flow cat and lastly Invida catback

Questions:
I live at 5000 ft of elavation and can’t find any information on how to tune timing when it come to be at higher altitude. To my understanding due to the less dense air if I tune timing at 5000ft and the drive down to see level I could experience knock due to the increase in air density. Is there any kind of correction map or spred sheet or am I out of luck and my only option is to get a timing map from some at sea level and run it until I take the time to tune timing at sea level.

Second question I do not fully understand how to properly adjust for a new boost controller and how to know how to change TD values any information would be extremely help full.

Lastly is there anyone who would be willing or recommend and good base map that is can flash on and start from the save time and good a feel for where the values of all the maps should start.

Any help of information or pointing in the right direction would be extremely appreciated thanks

Look up threads started by jon7009, he has posted an excellent base map to start with which you could flash right away.

Being at higher altitude will make your turbo work much more to reach boost levels intended for sea level (as the atmo pressure delta becomes much higher). It would be wise to target lower boost levels.

You would have to guesstimate within reason your ignition table's higher load cell values which you cannot reach at your elevation, but possibly could when at sea level.

Read up bleed style (stock 2-port) and interrupt style (3-port) boost controllers to get a general idea how they work.

Also read up on wastegate duty cycle (wgdc) and turbo dynamics - there are plenty of information in this forum as well as the internet.
Basically the higher the wgdc the more air is bypassed back to intake instead of pushing on the membrane of wastegate actuator which forces to open the wastegate flapper and lets the exhaust gas to bypass the turbine wheel. Simply spoken you can treat the wgdc as the % of reference boost pressure from the turbo which will get bypassed back to intake instead of wg actuator.
For boost curve specified by target boost table there is a specific amount of wgdc required to reach it (depending on the setup of the car).
There is a window of wgdc in the rom where the turbo dynamics can make adjustments based on the boost error (target boost - current boost). These are called initial and max wgdc tables. Without turbo dynamics active the wastegate duty cycle would sit at the value defined by initial table. Turbo dynamics can work only up to values specified by max wgdc table but they can go lower than initial. There are two turbo dynamics tables - proportional and cumulative/integral. The former is immediate correction based on the boost error, the latter (as the name implies) accumulates over time (but resets every time you come off boost).
The base maps provided by jon7009 have wgdc tables zeroed out which means your starting point will be at wastegate pressure (the pressure which your turbo setup actuator can hold when no pressure is bypassed back to intake).

Thank you for the information I feel that i undertstand the turbo and WGDC and altitude correction maps fairly well what I don’t understand is how will guesstimate my timing tables ?

As well as I understand how the boost controller works I don’t not understand how to apply that knowledge so if I need to change my TDC map for the new boost controller how much do I change the value and what do I log to verify that my change is correct ? Thank again for the info on the base map I will download it and check to see if it for JDM ecu after work thanks again

if you go up in air density, you go up in mass air flow
mass air flow grams per second, or mass air flow grams per revolution

timing for you on the stock ROM is based with an x-axis of grams per revolution

if going up 10% in atmospheric density, then your engine load goes up 10%
2 g/rev now becomes 2.2 g/rev
this example would put you into an area with different timing

say you're targeting 12 PSI @ 6000 RPM and you're at 200 g/s mass air flow, that would put you at 2.0 g/rev
no you go down in elevation and you're still targetting 12 PSI @ 6000 RPM but you're now at 220 g/s airflow. That would be 2.2 g/rev.

if you tune your car at 5000 ft, and then go to sea level or lower, you're mostly going to look at wastegate duty correctin for barometric pressure change: Boost Control > Wastegate Duty Compensation (Atm. Pressure)

if you're running the JDM EJ205 with AVCS and have it enabled, you probably are running a ROM which has proportional/integral boost control and probably not the boost control style that original USDM EJ205s ECUs came with, which is 'lazy ramping' style turbodyanmics. Continous/burst ramps in and has issues overboosting, much more of a pain to tune accurately. I think PID is easier, but newbs tend to disagree.

What is the calibration ID of the ROM you are using? also, do you know your barometric pressure in your area? if not I can look it up, what city/region are you in?

Thank you that is exactly what I was looking for! it makes sense that there isnt a compensation map because at high altitude I will never have the load to cross into the cell of the map that I would at sea level. Thank you for the help! My ecu ID is: 22611AJ800 and the barometric pressure where I live is 30.21 in. Thanks

so you're nearly at sea level anyways?

I'd 'center' the barometric wastegate correction for your normal pressure and modify extra duty for the lower pressures as you go up.

5000 ft about 25 inches Hg, roughly 12.27 PSI absolute pressure

I'd start with something like this, it's taken from comparing various ROMs where they only have one row, for this 2D table. Later vehicles moved to a 3D table.

Okay I am back sorry had a busy week. I got back after it tonight. Here is what I have so far. I pulled my JDM map and built a bit of a base map by setting initial WGDC to 0 and Max WGDC to 0. Also changing OL fueling top end to 10.2 and lastly pulling 5 degrees from to top end of base timing map.

My ECU ID from the map is: 3D04403005
This ecu has AVCS logic but I do not know if the base maps I am finding will work because this is a JDM ecu and I keep just find USDM.

As for the last post I was wrong on my pressure i had just looked it up but my actual atmospheric pressure is: 12.23psia

Would anyone be willing to build me a base map for this ECU ID with the atmospheric pressure correction table for my altitude? This would be incredibly helpful thanks.

Last question I have a K&N typhoon intake on the car, from everything I have read it sound like I should rescale the MAF in closed loop. Is this really necessary when short term fuel trim are going to make any find correction and from driving around I can see they are making very little percent correction. ALso all other parts the air intake and intercooler are stock. How necessary is it to rescale closed loop and will this bite me later down in the tune.

Thanks again

you'll want to rescale the MAF scaling entirely, for both open loop and closed loop (< 60 - 70 g/s) areas

STFT + LTFT (current) = fueling error % for closed loop
fueling final base / wideband = fueling error factor for open loop
if you request FFB in lambda and log wideband in lambda, it works just as well as doing both in gas AFR.

error in fueling is directly proportional to error in engine load, so if you're off by whatever percent fueling in open loop, then you're off by that amount of percent in engine load calculations. If your MAF scaling is way off from 40+ g/s up, and you have LTFT D cell applied to open loop, then you're erroneously modifying open loop load/airflow calcs.

You can also set it to run open loop all the time and tune the MAF entirely in open loop. Or you can sort between CL/OL status and throttle amounts to get approprate data for tuning the whole MAF scale.

Best to have the intake scaling as accurate as possible, so that when closed loop is doing it's job, you have minimal error and usage of it, and so that open loop doesn't throw you into funky load calculations.

USDM 16-bit ROMs never got AVCS, so they are tuned without it, and generally speaking, you want less timing in higher load/lower rpm during spool up when AVCS is being used than a non-avcs engine wants.

Best to start out with the AVCS table the JDM engine comes with. You'll adjust timing to suit your mods and fuel type, and then massaging AVCS with timing will be a go.

As for your atmospheric compensation, I'd suggest starting with it zero'd out and then modifying the table for the pressure ranges as you log data through them. I'm betting the table I last suggested is probably pretty close to what you might end up with if you centered it at sea level elevation.

Thank you for the info I will rescale the MAF for booth CL/OL. As for the base map I figured that it wouldn’t really be a reality so I will continue thank for the information.

This leads to my next question I don’t believe that I correctly understand the atmospheric correction table. To my under its purpose is reduce WGDC as psia drops to protect the turbo from over working it self to trace the same target boost. How did you come up with this numbers and why ? Couldn’t I zero out that table and then run the turbo harder all the time? (Td04 turbos are cheap to rebuild). How does this table effect me reaching target boost at different altitudes?

Thanks