fixing boost spike problem, need advice. Data logs inside. - Subaru WRX Forum
 
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#1 Old 12-11-2008, 05:51 PM
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boost spike problem, Data logs inside. All fixed....

I'm going back to stock BCS for winter, want to sell the MBC and control boost properly now that COBB released the race tuner software to edit their maps. I'm kind of new, but I'm a very fast learner and know what the basics of tuning are.

Here's the problem, when hooking up the stock lines with the stock pill on stage2 91 octane, I would hit target boost of 15.8-16psi before installing the MBC to give it a shot, but wanted to revert back to stock to retain the ECU limiting boost in case something went wrong. But after hookup, only just after I reset the ECU will it hit the target boost normally, any pulls after this and the boost goes up to 17.5+ and hunts down below the target and doesn't settle. Part throttle over mechanical boost makes the pressure hunt up and down between 5-10 psi and just goes back and forth. Seems like the BCS reacts too slowly to correct the boost. DAM is at 16.

Planning an EVOIII setup in the spring along with timing belt (102,000 miles but in awesome shape), but for now I want to go back to stock boost control until I get my prodrive EBCS (can I tune for this with the ATR software?).

Can't understand the problem but the BCS may be bad, I figured I’d ask you guys what to adjust first. Maybe WGDC tables could be lowered, and are the target boost tables supposed to have 17.28 rel. pressure as a target? That seems to be what its hitting but not like its supposed to. Thanks, I'll learn as I go.

This is Cobb APV2, Stage 2 91 octane tune. Car is an 02.

I attached some data logs in the next post so you guys can see whats going on.

-02 WRX Blouch 18G'd Juggernaut of Beastliness.

Last edited by Wasp642; 12-13-2008 at 06:43 PM.
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#2 Old 12-11-2008, 05:52 PM
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Heres the data logs, and i copied the above into works and spell checked it.

First one (Seconds.doc) is a 4th gear pull after reconnecting stock BCS and resetting the ECU by disconnecting the battery for 40 minutes.

Second one (2nd.doc) is a 5th gear run gradually holding about 1/3rd throttle and you can see the boost hunting up and down, then WOT.

Last one (3rdto4th.doc) is a 3rd to 4th gear pull, still overshot boost target.
Attached Files
File Type: doc Seconds.doc (93.5 KB, 122 views)
File Type: doc 2nd.doc (120.0 KB, 98 views)
File Type: doc 3rdto4th.doc (112.0 KB, 111 views)

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#3 Old 12-11-2008, 05:55 PM
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Please run a spell checker on your posts. I edited more than a dozen spelling mistakes that were BLATANTLY obvious with my web browser's spell checker. We don't ask that you be perfect, we just ask that you show enough respect for other members to try and make it readable.

Please read this:
Grammar and Punctuation.

PS: Please use the edit button to add to your posts if you forgot something. You should not need to double post.

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#4 Old 12-11-2008, 08:11 PM
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I was actually reading about the race tuner software today. I actually read in the Cobb forums that you CAN tune for the EBCS when you get it and become familar with the software. Best of luck with it.

Joshua
"2007 WRX- PPG'd, 20G- Tim Bailey tuned
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Cobbtuning.com"
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#5 Old 12-12-2008, 08:53 AM
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Only log in 3rd gear as this is the gear max boost is tuned for with Cobb maps and most others.Subaru OEM maps are tuned for max boost in 5th (FYI).Log WOT from 2k rpm to 7k rpm and log only:

wastegate duty cycle
turbo dynamics proportional
turbo dynamics burst
rpm
manifold rel. pressure
air intake temps

Those are important for tuning boost and logging more parameters than needed will result in less resolution.You probably need to tweak either the turbo dynamics tables or the wastegate duty compensation per intake temps table.Also since your running a Cobb OTS map,try contacting them.They might fix it for you.

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#6 Old 12-12-2008, 12:24 PM
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Also the map calls for the restrictor pill to be drilled out with a #55 drill bit... If its not drilled out, not enough pressure will make it to the wastegate, which can cause overboosting.
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#7 Old 12-12-2008, 02:15 PM
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Originally Posted by TurboRyan View Post
Also the map calls for the restrictor pill to be drilled out with a #55 drill bit... If its not drilled out, not enough pressure will make it to the wastegate, which can cause overboosting.
You must be reading the wrong map notes.The OP has a 02 WRX.

http://www.accessecu.com/accessport/...091%20v130.pdf

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#8 Old 12-12-2008, 04:14 PM
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my bad... I was looking at the wrong map notes....
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#9 Old 12-12-2008, 06:46 PM
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Thanks for chiming in dumdum, what can i change the values to for a starting point in the turbo dynamics table, and do i change all the cells in the WGDC table?

I tried lowering the WGDC table values by about 1.0-2.0 in each cell, did no good, still overshot and spiked to 17.4psi. Should i lower the values more drastically? My DAM was at 6-7 on the way home from work today (50 miles) which tells me the ECU is mad at me for some reason. I had to merge onto the freeway WOT since cars were coming, and a spike may have caused the low DAM.

What would need to be tuned if i just used a prodrive 3 port solenoid with the stage 2 map? just the WGDC tables? which way to adjust and whats a good rule of thumb for starting to tune for that EBCS? -5% on the values?

Thanks, i'm new to tuning, but not so much.

-02 WRX Blouch 18G'd Juggernaut of Beastliness.
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#10 Old 12-12-2008, 06:59 PM
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Heres my boost target table from the OTS map im using. They're claiming 15.8psi target boost in the notes, but why do i see 17.28 in there?

Also included my WGDC table and turbo dynamics.
Attached Files
File Type: doc boost targets.doc (31.0 KB, 93 views)
File Type: doc WGDC table.doc (22.0 KB, 92 views)
File Type: doc Turbo Dynamics.doc (22.0 KB, 93 views)

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#11 Old 12-12-2008, 07:45 PM
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Quote:
Originally Posted by Wasp642 View Post
Thanks for chiming in dumdum, what can i change the values to for a starting point in the turbo dynamics table, and do i change all the cells in the WGDC table?

I tried lowering the WGDC table values by about 1.0-2.0 in each cell, did no good, still overshot and spiked to 17.4psi. Should i lower the values more drastically? My DAM was at 6-7 on the way home from work today (50 miles) which tells me the ECU is mad at me for some reason. I had to merge onto the freeway WOT since cars were coming, and a spike may have caused the low DAM.

What would need to be tuned if i just used a prodrive 3 port solenoid with the stage 2 map? just the WGDC tables? which way to adjust and whats a good rule of thumb for starting to tune for that EBCS? -5% on the values?

Thanks, i'm new to tuning, but not so much.
If you have never tuned a forced induction car before,now would not be the time to learn especialy when trying to change to a 3 port.Spend some time reading on Romraider.com and Cobb's StreetTuner manual.Seriously,call Cobb and tell them what is going on.They can send you a new map.Overboosting 1 psi is not going to cause DAM to fall.All the wastegate tables have to be moddified with a 3-port.Also make sure you are running the both the stage 2 91 base and realtime map.

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#12 Old 12-13-2008, 11:44 AM
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Tried to call cobb last night, it was too late so i have to wait until monday. I emailed them though but have not gotten a response yet. I just can't unserstand how the solenoid is doing this after 4 months of just being disconnected, it was cleaned and capped too.

Another interesting note last night, when the DAM was 6-7, i though boost control was turned off and limited to mechanical boost. However, I would still boost up to the spike around 16-17psi??????????

Either way, i ordered a prodrive EBCS last night too.

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#13 Old 12-13-2008, 05:12 PM
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Originally Posted by Wasp642 View Post
I just can't unserstand how the solenoid is doing this after 4 months of just being disconnected, it was cleaned and capped too.
It probably not the solenoid.It has to do with the ambient temps.Colder air is denser and now wastegate duty cycle compensation per intake temps are being applied along with everything else.


Quote:
Originally Posted by Wasp642 View Post
Another interesting note last night, when the DAM was 6-7, i though boost control was turned off and limited to mechanical boost. However, I would still boost up to the spike around 16-17psi??????????
I think a DAM of 4 disables boost.Pretty sure Street Tuner can access this parameter.

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Originally Posted by Wasp642 View Post
Heres my boost target table from the OTS map im using. They're claiming 15.8psi target boost in the notes, but why do i see 17.28 in there?
Look at the rpm associated with 17.28.It's 2300 rpm.No matter what gear your in,hitting 17 psi at that low an rpm isn't quite possible.They do that to ramp up the turbo dynamics for better spool.They set it to a unatainable limit and then bring the boost targets down closer to attainble targets for faster spool only.

AccessTUNER Tuning Guide and Worksheet for Subarus - COBB Forums

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Last edited by mosc; 12-13-2008 at 08:35 PM.
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#14 Old 12-13-2008, 06:02 PM
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Thx for the help dumdum. I was reading through romraider last night and today. I adjusted my WGDC air temp. compensation table, duty cycles, and boost targets to where i want them to be. After 3 trys of small adjustments, finally got rid of the spike, and hits boost targets fast and smooth like it should. No more boost oscillation on part throttle or full throttle either. DAM is back to normal and car is running nice and strong. I told you i learn fast

What will have to be done to the WGDC tables (starting point) for tuning the prodrive? any other tables need to be modded for it too?

Thanks...

Heres a 3rd to 4th gear pull with the mods to the map done.
Attached Files
File Type: doc modded3to4.doc (87.0 KB, 104 views)

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#15 Old 12-14-2008, 06:28 PM
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Originally Posted by Wasp642 View Post
Thx for the help dumdum. I was reading through romraider last night and today. I adjusted my WGDC air temp. compensation table, duty cycles, and boost targets to where i want them to be. After 3 trys of small adjustments, finally got rid of the spike, and hits boost targets fast and smooth like it should. No more boost oscillation on part throttle or full throttle either. DAM is back to normal and car is running nice and strong. I told you i learn fast

What will have to be done to the WGDC tables (starting point) for tuning the prodrive? any other tables need to be modded for it too?
Glad to hear you got the problem sorted out!I'm not 100% familer with the Prodrive unit but using both the Perrin and the GM solenoid you have to cut the maximum wastegate duty cycle table by almost 30%.The the turbo dynamics and intake air temp compensation will have to be tweaked as well.That part is kinda trial and error.

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