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Old 12-26-2013, 02:44 AM   #1
hally
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Member#: 123652
Join Date: Aug 2006
Chapter/Region: International
Location: Australia
Vehicle:
2003 STi Built EJ257
APS SR55 380WHP@20psi

Default Tune feedback please, hesitation

Hi all,
Am hoping anyone could provide me some feedback on my tune. I'm having issues sorting out driveability, if i really slowly open the throttle it's fine but normal accelerating upto suburb limits, it has a big hesitation, particularly after gear changes, the whole car shudders through the driveline.

Attached is the tune and a learning view also to show stored af and knock correction.

Mods include (2003 ADM STi) - ported heads, 278/274 avcs cams, spec c one piece manifold, ID1000's, 3in maf cai, fmic, uel headers, gt3076, 3in tbe. 380hp atw, 20psi.

Thanks in advance.

This is the Tune itself

Learning view screenshot
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Old 12-26-2013, 03:57 AM   #2
Concillian
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Join Date: Feb 2001
Location: Dublin, CA
Vehicle:
2002 WRX Sedan
Midnight Black

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Can't really tell without logs of the issue.

First and foremost: Has this ever worked right? Do you know for sure if this is a tuning or mechanical issue? I'm assuming by posting here that your first assumption is that mechanically things are correct and this is a tuning issue. Hopefully the issue is that simple.

If it's a tuning issue, this is usually due to small errors in fueling that won't be seen through Learning View. LV is very "general." Not specific enough to nail down an issue like this. In all likelihood this is a combination of tip-in enrichment tuning and general fuel tuning.

1) Run romraider on the MAF tab accelerating smoothly and slowly from ~2000-4000 RPM in 1st through 4th 2 or 3 times, preferably on different slopes. Alternately drive around a while (20 mins+) taking particular care to accelerate smoothly and slowly. dMAFv/dt value on that tab should be set pretty low .1-.2 or .01 to .02, I forget the units. Last digit a 1 or 2. Goal here is to get the same RPM at several different loads and a good number of samples.
Interpolate and screenshot.
This will show any issues with your MAF scaling in your cruising range. If there are issues, you obviously correct your MAF table and repeat until average correction low to high MAFv is <5% (pref as low as possible) delta from one another. If things are not able to be consistently dialed in, then having them all on one side or the other of zero is preferable to having them zig-zag across zero.


2) Tune closed loop compensation table to run a little richer on low loads. Cams generally want a little rich at low loads. These tables vary by ECU, but most use a compensation in AFR points. "Add" -0.2 to -1 AFR to low load and low RPM. Add the most fuel at low RPM AND low loads. Most cams are okay at stoich, but going a little richer, like 14.5 or 14.3 will help keep the car from shuddering, which most often happens when it sees some 15+ AFRs on throttle transition. Putting the average a little rich allows for the lean-side errors to still be around 14.7-15 AFR.

Remember the zig-zags in #1? 1% deviation at 14.5 AFR is 0.145 AFR. If you see consistent 2% variation in the average, this results in about 0.3 AFR.

3) If that's all good, but you're still having the issue, check tip in.

here you want to cruise steady 10-15 seconds and press the throttle ~5-10% and hold steady 10-15 seconds. Go back to your steady cruise at low throttle and repeat with a little more throttle... ~10-15%. Repeat until you're giving very large throttle shifts.

Check AFR in your logs. There will be some time delay between when TPS moves and you see AFR changes in your log. Be sure to accomodate this shift. Add or subtract tip-in until these transitions generally give you between ~14.5 and 13 AFR via logging.

4) Lastly, if your ROM has low pulse width compensation tables defined, adjust these for your injectors. Most of the low pulse width compensation table definitions require a % fuel added at given pulse widths.

ID has great info on their site, including a graph of injector vs. pulse width. Most of the line is very linear except for the very low pulse widths. If you print out the graph (or edit it with an image editing program) you can extend the "linear" region line to low pulse widths. Subtract out the latency and estimate % fuel needed at low pulse widths in the compensation tables.. 14v is most important.

All four of those things and your car should drive very close to stock even with significant mods like you have. Those cams may not allow totally stock like driving, but you can definitely get rid of the shudders unless it's something mechanical.

Last edited by Concillian; 12-26-2013 at 04:07 AM.
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Old 12-26-2013, 07:33 PM   #3
ProfessWRX
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06 WRX

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Quote:
Originally Posted by Concillian View Post
Can't really tell without logs of the issue.

First and foremost: Has this ever worked right? Do you know for sure if this is a tuning or mechanical issue? I'm assuming by posting here that your first assumption is that mechanically things are correct and this is a tuning issue. Hopefully the issue is that simple.

If it's a tuning issue, this is usually due to small errors in fueling that won't be seen through Learning View. LV is very "general." Not specific enough to nail down an issue like this. In all likelihood this is a combination of tip-in enrichment tuning and general fuel tuning.

1) Run romraider on the MAF tab accelerating smoothly and slowly from ~2000-4000 RPM in 1st through 4th 2 or 3 times, preferably on different slopes. Alternately drive around a while (20 mins+) taking particular care to accelerate smoothly and slowly. dMAFv/dt value on that tab should be set pretty low .1-.2 or .01 to .02, I forget the units. Last digit a 1 or 2. Goal here is to get the same RPM at several different loads and a good number of samples.
Interpolate and screenshot.
This will show any issues with your MAF scaling in your cruising range. If there are issues, you obviously correct your MAF table and repeat until average correction low to high MAFv is <5% (pref as low as possible) delta from one another. If things are not able to be consistently dialed in, then having them all on one side or the other of zero is preferable to having them zig-zag across zero.

2) Tune closed loop compensation table to run a little richer on low loads. Cams generally want a little rich at low loads. These tables vary by ECU, but most use a compensation in AFR points. "Add" -0.2 to -1 AFR to low load and low RPM. Add the most fuel at low RPM AND low loads. Most cams are okay at stoich, but going a little richer, like 14.5 or 14.3 will help keep the car from shuddering, which most often happens when it sees some 15+ AFRs on throttle transition. Putting the average a little rich allows for the lean-side errors to still be around 14.7-15 AFR.

Remember the zig-zags in #1? 1% deviation at 14.5 AFR is 0.145 AFR. If you see consistent 2% variation in the average, this results in about 0.3 AFR.

3) If that's all good, but you're still having the issue, check tip in.

here you want to cruise steady 10-15 seconds and press the throttle ~5-10% and hold steady 10-15 seconds. Go back to your steady cruise at low throttle and repeat with a little more throttle... ~10-15%. Repeat until you're giving very large throttle shifts.

Check AFR in your logs. There will be some time delay between when TPS moves and you see AFR changes in your log. Be sure to accomodate this shift. Add or subtract tip-in until these transitions generally give you between ~14.5 and 13 AFR via logging.

4) Lastly, if your ROM has low pulse width compensation tables defined, adjust these for your injectors. Most of the low pulse width compensation table definitions require a % fuel added at given pulse widths.

ID has great info on their site, including a graph of injector vs. pulse width. Most of the line is very linear except for the very low pulse widths. If you print out the graph (or edit it with an image editing program) you can extend the "linear" region line to low pulse widths. Subtract out the latency and estimate % fuel needed at low pulse widths in the compensation tables.. 14v is most important.

All four of those things and your car should drive very close to stock even with significant mods like you have. Those cams may not allow totally stock like driving, but you can definitely get rid of the shudders unless it's something mechanical.
You say go richer, I believe he needs to lean it out. Large fuel pulses give more cam surge than a lean mixture ever would. I found immense driveability gains in leaning out my low load fuel trims after a huge cam install. As you said though, only a log can help us truly narrow it down, but his learning view looks rich or maybe I'm backwards on the learned values for these ECMs.
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Old 12-27-2013, 12:59 AM   #4
hally
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Member#: 123652
Join Date: Aug 2006
Chapter/Region: International
Location: Australia
Vehicle:
2003 STi Built EJ257
APS SR55 380WHP@20psi

Default

Thanks for the replys guys. What parameters should i log and what load/thottle/rpms should i aim to achieve whilst logging?

Thanks.

Last edited by hally; 12-27-2013 at 01:15 AM.
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Old 12-28-2013, 01:03 PM   #5
ProfessWRX
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Member#: 323379
Join Date: Jun 2012
Vehicle:
06 WRX

Default

Quote:
Originally Posted by hally View Post
Thanks for the replys guys. What parameters should i log and what load/thottle/rpms should i aim to achieve whilst logging?

Thanks.
You need to log both fueling adjustments. One is a short term and the other is learned forget what they are both called. Also Maf voltage, load, tps, feedback knock, and wideband o2.
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Old 12-28-2013, 06:56 PM   #6
nmlittlebigman
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Chapter/Region: SWIC
Location: Arrey, NM
Vehicle:
2015 WRX LTD
WRB

Default

AF Correction #1 = Short term fuel trim
AF Learning #1 = Long Term fuel trim

Your Learningview indicates that you are too rich.
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Old 12-29-2013, 04:57 AM   #7
Shadow27AU
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Join Date: Jul 2011
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Your tip in is way too high at low to mid throttle changes imo. You need to adjust your tip in from the stock tip in values. You take stock tip in values and times them by the change in injector scalar size.

For example,
- Your stock injector size is 552.47, your scalar in your tune is 801.39.
- 552.47 / 801.39 = 0.689
- Times stock tip in values by 0.689

I came up with values of:

0.384
0.448
0.544
0.672
0.8
0.96
1.152
1.312
1.504
1.664
1.856
2.016
2.176
2.4
2.624
2.848
3.072
3.328

Try those out.

Out of interest, where was the car tuned originally? The mapping looks familiar.
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