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Old 06-08-2009, 07:02 PM   #1
uaoSTI
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Join Date: Mar 2008
Chapter/Region: RMIC
Location: SLC, UT
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2005 Subaru STI
Silver

Default Need help with a datalog

I am experienceing a massive throttle body shut down at full throttle for some reason and need some help with interpreting the data. It is a .csv from my AP in my 05 STI (20g, 745 injectors, wahlboro pump). Cobb tuned on the dyno but for some reason I have not been able to smooth it out yet. I am hoping someone can look at the file and let me know what parts I may need to fix this hiccup.

How can I upload a file? Any clues?

here is a pdf but the layout is fubared

https://app.infopia.com/tainswor/ima...d/datalog4.pdf

send me a PM with your email and i will send the csv over
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Old 06-08-2009, 07:19 PM   #2
nme187
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Looking over that log, it's running good.
.7% STFT is GOOD! Jebus bad fuel alone will jump it 2%+/-.
The DAM is constant 1 aka perfect.
The DA never reads - in boost so your not knocking.
Not even going to quote the A/F's

What's going on with it? It's too hard to read in PDF format to look across the board.
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Old 06-08-2009, 07:47 PM   #3
MXJS
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Log RPM, Load, MAF voltage, throttle position, and boost, and wideband A/F. I had a the exact same problem once. My MAF extension harness was garbage and the ecu was getting a bad signal from it. I rewired it with stinger speedwire and it fixed the problem.
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Old 06-08-2009, 08:34 PM   #4
uaoSTI
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Thanks for the help so far.

What is the issue? Full throttle (99.96%) at 3800 rpm's then the TB goes to 35% at 4084 rpm's then back up to 99%. The car is stuttering in a full pull every time in 4th and 5th gear. hard to replicate in 3rd.

Looking at the logs you can see where the throttle is going from 99.96 to 50% or less during acceleration



I will try a new pull asap with the fields recommended. I am praying its a mechanical issue (ie, maybe MAF thing you pointed out).

From my original file MAF voltage looks consistent for the same times as the image above

4.52
4.56
4.58
4.58
4.52
4.22
4.1
4.2
4.36
4.46

Also Air/Fuel is 11.04 constant

Last edited by uaoSTI; 06-08-2009 at 08:44 PM.
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Old 06-08-2009, 09:02 PM   #5
uaoSTI
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Old 06-08-2009, 11:59 PM   #6
MXJS
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Try swapping maf's with someone. When i had the problem the MAF voltage looked normal as it does in your log. Has it always had this problem or is it a recent development?

PS: the air/fuel will always show 11.04 under wot because it is not a wideband. It is pretty much worthless to log unless you are logging during closed loop operation.
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Old 06-09-2009, 12:48 AM   #7
TurboJunkie85
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If swapping the Maf doesnt help try re-scaling your maf I think you are able to do that on the AP race tuner
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Old 06-09-2009, 09:16 AM   #8
MXJS
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Also forgot to mention the first thing you should do. Check for vacuum/boost leaks.
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Old 06-09-2009, 09:50 AM   #9
uaoSTI
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Quote:
Originally Posted by TurboJunkie85 View Post
If swapping the Maf doesnt help try re-scaling your maf I think you are able to do that on the AP race tuner
got a link on how to do this?

And I believe I dont have any boost leaks (recently t-bolt clamped all turbo and Y Pipe hoses). Nonetheless I will keep looking.

Thanks.
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Old 06-09-2009, 09:56 AM   #10
xblackdeathx
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I know how you can fix it. Drive it off a cliff?
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Old 06-09-2009, 10:27 AM   #11
uaoSTI
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Quote:
Originally Posted by xblackdeathx View Post
I know how you can fix it. Drive it off a cliff?
I just text'd you homo
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Old 06-09-2009, 11:00 AM   #12
TurboJunkie85
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Log your G/sec and your maf voltage from idle to WOT and then pull up your maf scaling values and see if it's off you might wanna get a couple of logs in before you start making adjustments
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Old 06-09-2009, 11:45 AM   #13
MXJS
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I wouldn't recommend making any changes to the MAF scaling if it was tuned correctly by cobb. If it wasn't tuned correct, i wouldn't recommend making any changes in open loop without a wideband A/F reading. An improperly scaled maf will cause a rich or lean condition, but i don't see it causing the TB to close. I could be wrong though.

uaoSTI - Do you have a fuel pressure gauge?
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Old 06-09-2009, 11:50 AM   #14
uaoSTI
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uaoSTI - Do you have a fuel pressure gauge?[/quote]

i do not actually (oil temp, boost, A/F). i am running the Wahlboro intake and deatschwerks 740 injectors)

Basically the car sputters heavily at those logs and then starts to climb again. i think the map is good so it may be electrical or mechanical. i may have to give Solid a test ride to see if they can figure it out....
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Old 06-09-2009, 11:58 AM   #15
MXJS
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Well if you wanted to diagnose it yourself this is what i'd do:

Swap maf with someone else
Pressure test IC piping and vacuum lines
Check to make sure fuel pressure isn't dropping out (bad fuel pump or FPR)
Make sure spark isn't being blown out (fouled plugs or too big of gap)
Log requested TP vs actual TP to see if its a bad TPS

If i think of anything else i'll let ya know. I'm confident its a mechanical/electrical problem if it hasn't always done it.
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Old 06-15-2009, 03:27 PM   #16
uaoSTI
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just an update:

i put in new iridium plugs (gapped to .025) and am still having the same issues. I dropped the car off at Solid in the hopes they can wrap their brains around it....
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Old 06-30-2009, 02:03 PM   #17
uaoSTI
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possibly last update:

Paul @ solid discovered 2 things:

1. WG diaphram was torn to bits
2. lower o ring in WG was brittle and fried to death

New parts on the way. hopefully bliss follows.
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