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Old 04-10-2021, 12:15 PM   #26
HarryCaveMan
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Quote:
Originally Posted by cianuro View Post
I'd recommend getting a map that has a tune for the vf52 already as it will have the proper adjustments for the turbo dynamics as mentioned in the previous post. You'd need it to be an open map so you can tweak it, which would probably only be possible via local hands-on tuning. When I purchased my maps they were open, so I was able to tweak the AFR, then mess with the rear O2 until I was able to replace it.

Right now my car is down. Broke the throw out bearing when covid started and because I was being quartered at my job for several weeks at a time, it took me 6 months to get it back running, only to have the air pump die on me and crack the radiator at the same time. All that's left is venting the rad and new registration since it expired.
I have AccessTuner which allows me to modify/combine Cobb OTS maps.

I could use an OTS map from an 09 STI (didn't that come with a vf52?) for example to get the v52 PID tables for. All other parts would be the stock ones on my 2008 WRX, So I'd likely need all the other tables from that map? Most importantly the primary fueling table values in the 08 WRX OTS map are all based on calibrations for my stock intake and MAF housing.

Also I can feel your head gasket's terror from here when you mention the cracked radiator.
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Last edited by HarryCaveMan; 04-10-2021 at 01:40 PM.
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Old 04-10-2021, 01:56 PM   #27
cianuro
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Quote:
Originally Posted by HarryCaveMan View Post
I have AccessTuner which allows me to modify/combine Cobb OTS maps.

I could use an OTS map from an 09 STI (didn't that come with a vf52?) for example to get the v52 PID tables for. All other parts would be the stock ones on my 2008 WRX, So I'd likely need all the other tables from that map? Most importantly the primary fueling table values in the 08 WRX OTS map are all based on calibrations for my stock intake and MAF housing.

Also I can feel your head gasket's terror from here when you mention the cracked radiator.
You'd need to be able to open the 09 map, transfer all the tables to excel, then paste them to the OTS map. You can't apply an OTS 09 map to an 08.
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Old 04-10-2021, 02:18 PM   #28
HarryCaveMan
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Quote:
Originally Posted by cianuro View Post
You'd need to be able to open the 09 map, transfer all the tables to excel, then paste them to the OTS map. You can't apply an OTS 09 map to an 08.
When I say combine that is essentially what I mean, to build a new map that has features of both. I can populate the PID tables in the 08 map with the values from the 09 map.
**Update:
I see..... I'm unable to open the 2010 map in my version of AT which is for a 2008, So I'll have to get the values from some other source...

What I would want to consult an engineer for would be to learn how changing the turbo affects the math, here's an example:

First of all, I'm not quite certain what the "proportion" metric means in this case.

When I did PID before (one time in undergrad quadcopter project) P was for "position" which essentially meant "magnitude and direction of deviation from desired position" or (desired gyro signal - actual gyro signal (in degrees (signed int))). The I and D were just the Integral (cumulative sum) and Derivate (change/timestep) of the same metric WRT time. Here are guesses I came up with based on my previous experience:

- Boost Error (Target-MAP)?
- marginal or "proportional" boost error (Boost Error/Target)
- marginal or "proportional" boost error (Boost Error/MAP)

Then there's the graphs, does the line represent the coefficient to be used under the conditions defined on the axes?

Understanding things like this can help me start to build the complete picture and figure out what assumptions I can test, for example:

- With a larger wastegate port on the VF (or another future turbo). It seems like this would primarily affect the way Derivative maps to WGDC, because a smaller change in WGDC would result in a larger change in flow... well, maybe, under certain conditions... I don't know xD. It would definitely mean that you would need less WGDC to achieve the same bypass volume, and bypass volume is certainly related to the derivative of compressor RPM which is related to the derivative of boost pressure...

When I look at the tables, it appears to be a PI system only and not a PID system, is this the case?

Anyhow, even this conversation is great because rubber ducking with people helps me think things through...

Last edited by HarryCaveMan; 04-11-2021 at 01:19 PM.
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Old 04-13-2021, 09:39 AM   #29
HarryCaveMan
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Default Self tuning my vf52 swap

Starting to finally put all the pieces of info I have been collecting together in a meaningful way.

One thing I notice is that EFI-U (aka COBB) seems to incorrectly describe the boost control system as a PID controller when it is actually only a PI controller...please correct me if I'm wrong here.


I'll be going into more detail when I actually start tuning, after I install the new turbo, later this month. I found on this thread RomRaider which is incredibly helpful.
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Old 04-16-2021, 02:23 PM   #30
benflynn
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No engineer or tuner has the answer to this. And getting it correct is much easier than u are thinking. Take the info, make an intelligent guess and test. Repeat.
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