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Inconsistent boost levels in different gears

5K views 12 replies 3 participants last post by  jbreezy 
#1 ·
I couldn't find anyone with a similar issue, so...
WOT Accelerating, my boost in 1st and 2nd gear is about 15psi. But 3rd and 4th gear its only about 5-7psi. But that's just when Accelerating hard from 1st and shifting through the gears. If Im cruising (without Accelerating hard) in 1st or 2nd then I WOT in 3rd gear I get 15psi.
Does anyone know what is going on?
I'm wondering if it needs to be dyno tuned.
I have a 2003 WRX
MODS:
catless uppipe,
divorcedwastegate 3inch downpipe,
2.5 inch catback,
Cobb access port with stage 2 ebcs flashed,
Cobb ebcs.

It couldn't be my 3inch to 2.5inch exhaust causing an issue could it?

Would my access port tune need to be helped with a dyno tune to get consistent and correct boost levels?

Thanks, I appreciate the help and feedback
Land vehicle Vehicle Car White Rim


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#5 ·
Check your knock parameters on your Cobb. That's a bit weird and I wouldn't be surprised to see the ECU temporarily pulling boost.

Logging throttle, RPM, load, boost, along with your boost control parameters (wastegate duty cycle) would help tell us if it was a mechanical or ECU related cause.
 
#6 ·
I don't usually shift at redline, most the time when pushing my car I shift around 6000 rpms. I'm not quite sure what rpm I reach peak boost.

I will datalog tonight and then post by tomorrow. Thanks for all the help so far!

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#8 ·
datalog results

So i did a few datalogs. First of all, my 3rd gear was not acting up like normal, so that is odd. but not necessarily good. because it looks like i do have engine knock... just not quite sure where my problem is or how to fix it. hopefully you guys can help me figure it out.

datalog 1,2,and 3 are with my current tune. which i put on a couple weeks ago when i got my ebcs. (stage2 91 ebcs normal wastegate)

yesterday as i was doing the datalogs i realized i was overboosting a little. so i changed the tune to low wastegate.

so datalog 4 and 5 are with the tune stage 2 91 ebcs low wastegate.

since i just reflashed and reset my ecu, i dont know how accurate these numbers are because the ecu is still learning the tune.

i do know that my DAM was at 9, now at 12. it should be 16. but other than that i dont know what im really looking for.

so if you could help me figure out my problem and how to fix it i would appreciate it! thanks!
 

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#9 ·
it looks like my half my datalogs got cut off changing to a pdf.... let me know if you need to see other data such as: intake temp, maf g/s, maf voltage, rpm, td boost error, throttle position,vehicle speed, wastegate duty, and wastegate max. ill try to find a way to post it all
 
#10 ·
I'll take a look at them more tomorrow. I'm headed out for the evening.

Without even opening yours, try not to post too many parameters per log. You are best off taking a couple different logs with RPM/load/throttle/1-3 other parameters. The more you add on, the slower the recording rate.

Keep an eye on that DAM in the mean time. It should climb back up to 16 fairly quickly. That's something you don't want falling under 16, but it resets to 50% or so of it's range when the ECU is reset in some models, I think.
 
#12 ·
Hey. I just wanted to let you know that I didn't forget about this. I've been pretty tied up with work the past week or so. I'll get around to checking those logs out sometime soon though.
 
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