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 Post subject: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 3:04 pm 
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When I tuned a 2008 WRX, I noticed that in 2nd gear, the requested torque was lower than in 3rd or 4th gear. This prevented full WOT in 2nd gear at low rpm. I had to change the DBW tables to get full WOT in 2nd gear.

The 2008 LGT in sport sharp mode didn't have this effect.

Has anyone else noticed this in any other cars?


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 3:20 pm 
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can you post the logs and map?


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 3:38 pm 
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Here's a rom and logs.

The rom is an intermediate tune so I had changed some stuff in it. This is when I found the problem. However, when I looked at all the old datalogs, the 2nd gear requested torque was the same.

BTW, this rom is for a 2008 WRX with a VF52 at high altitude (12 psi atmospheric).


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 5:23 pm 
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Do have any logs with req torque and target throttle plate pos showing the behavior? The ones shown there for 2nd gear req torque look fine and should result in 100% target throttle plate pos. That is, it is important to determine if the req. torque is dropping or the target throttle plate pos. is being modified after the fact (or replaced by some alternate logic).


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 5:47 pm 
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I went through the calculations, the lower requested torque below 3500 rpm in 2nd gear will definitely result in a lower throttle position.

Here's the same data that I posted. Notice that in 2nd gear below 3500 rpm, the requested torque is lower.

At first, I thought he wasn't pushing down on the accelerator all the way but he was. I'll ask him if he'll be willing to change the DBW table back to stock-like and relog with requested torque.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 6:06 pm 
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If you look at the base requested torque (rpm) table:
Attachment:
SS_67.jpg


The base req. torque is lower at low RPM. Based on this log, the ratio would be >1.0 starting at line 2:
Code:
500   0.81   2045   0   0   17   -0.87   76.08   222.29
735   1.03   2116   -1.41   0   19.5   0.44   73.33   285.12
985   1.11   2235   -1.41   0   25.5   1.02   68.63   290.39
1235   1.22   2352   -1.41   0   23.5   1.74   75.69   301.42
1469   1.35   2492   -1.41   0   22   2.76   74.9   310.57
1719   1.54   2669   -1.05   0   19   4.21   68.63   312.42
1969   1.81   2845   -1.05   0   14.5   6.24   61.96   314.67
2219   2.15   3058   -1.05   0   11.5   9.43   60.78   315.41
2454   2.6   3262   -1.05   0   9.5   13.93   53.33   315.95


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 6:42 pm 
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Sorry. I might have posted the "changed" rom. I changed the base requested torque table to get WOT in 2nd gear.

I don't have romraider here right now.

I'll double check when I get home.

Do you have a stock 2008 WRX rom? I was using the stock DBW tables before I changed it.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 6:49 pm 
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Sorry. It looks like the log was done right before he flashed the changed rom. The previous rom was the one where I changed the base table to get WOT.

Here's the rom that he used. It should have the stock requested torque base table.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 6:52 pm 
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here it is. it is higher.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 7:21 pm 
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Yes. I lowered it so that the ratio became greater than 1.


Last edited by mickeyd2005 on Thu Feb 19, 2009 7:37 pm, edited 1 time in total.
removed interjections


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 7:28 pm 
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Then that had no effect? I don't understand.

If it is still a problem, see if he can log:
1. RPM, load (1-byte)
2. accel. opening angle%
3. throttle opening angle%
4. req. torque
5. target throttle plate pos
6. gear

and do a 2nd and 3rd gear run.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 7:35 pm 
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Look at the STOCK base requested torque table for less than 3500 rpm, the ratio of

requested torque / base requested torque

for 2nd gear and less than 3500 rpm, it will be less than 1.0. Therefore, WOT isn't achieved in 2nd gear below 3500 rpm on the stock DBW settings.

To correct it, I lowered base requested torque so that the ratio became greater than 1.0 for 2nd gear.

It does work. 2nd gear boost comes on much quicker now.

I'll ask him if he'll change the tables back to stock and re-datalog.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 7:45 pm 
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Right. What I didn't understand was if you were saying that the throttle opening was 100% after you made the changes to the base req. table in 2nd gear or not? If it is, then there's really no additional logic coming into play and no reason to do any further testing.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 7:56 pm 
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Yes, after I made the change, the throttle opening is now 100% in 2nd gear.

I just wanted to know if there is another requested torque table for per gear compensation and if other cars have it.


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 Post subject: Re: Per Gear compensation for Requested Torque
PostPosted: Thu Feb 19, 2009 8:08 pm 
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Ok, I see what you are saying now. The requested torque for 2nd gear only is lower than what is determined by the currently defined req. torque tables. I'll look into it and see if I can determine what is going on. Wondering if the 08 STi has this behavior as well?


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