Subaru WRX Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter · #1 ·
2006 Impreza WRX STI

Hi everyone, I'm having issues with my 2006 STI. It currently has a Cobb Catback, and a Cobb SF Intake. I got the car without a tuner, So the only drive I had made was to take it home when I bought it so I had garaged it until I could afford an Accessport.

Anyways, my issue is that it is only building half-ish boost. Before the tuner I realized that it was only building around 7.25lbs of boost, and it would randomly spike up to 14.5lbs(target boost) on very little of the pulls. It can be an entirely new pull or during mid pull 5th gear it will just HIT ME with the full boost then go back to the lower boost. Anyways, I just got my car back out of the garage and got my tuner. I flashed a Stage 1 93 OTS map on the car, and everything went well. I went out and did 2 pulls, I thought it was fixed, I was hitting my target boost of 16.5lbs(Stage 1 adds 2lbs). I then went to someones house and picked someone up, and went to show him what the car could do... and it was back to half boost except this time it boosts to around 8-12lbs instead of 7.25lbs...

I've already cleaned the MAF Sensor, I did my best checking for vacuum and boost leaks(restrictor pill IS there and lines are correctly routed), with some carb cleaner. Any suggestions are helpful...

Sent from my SM-G950U using Tapatalk

Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
It sounds like your IAM has been reduced to where the ECU is pulling boost.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #3 ·
It sounds like your IAM has been reduced to where the ECU is pulling boost.
Is there any way to log this to find out what is causing this issue.. I'm pretty new to this whole Subaru thing... I guess my end answer is how would I go about confirming this issue and if it is how would I go about fixing it.


Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
Is there any way to log this to find out what is causing this issue.. I'm pretty new to this whole Subaru thing... I guess my end answer is how would I go about confirming this issue and if it is how would I go about fixing it.


Sent from my SM-G950U using Tapatalk
With engine management, yes.

The parameter is IAM (Ignition Advance Multiplier) with Open Source definitions or DAM (Dynamic Advance Multiplier) with Cobb AP.

IAM/DAM is primarily a strategy to deal with low-octane fuels, but since it can pull timing depending on the Dynamic Advance table, it's also a "gross" timing adjustment strategy. Beyond bad gas, it can also be due to vacuum leaks and any modification that changes the calibration between LOAD and FUELING i.e. uncalibrated fuel injectors, intake, exhaust etc.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #5 ·
With engine management, yes.

The parameter is IAM (Ignition Advance Multiplier) with Open Source definitions or DAM (Dynamic Advance Multiplier) with Cobb AP.

IAM/DAM is primarily a strategy to deal with low-octane fuels, but since it can pull timing depending on the Dynamic Advance table, it's also a "gross" timing adjustment strategy. Beyond bad gas, it can also be due to vacuum leaks and any modification that changes the calibration between LOAD and FUELING i.e. uncalibrated fuel injectors, intake, exhaust etc.
Hi again Zax,

I'm not sure you could give me any more knowledge on what to do but I've narrowed down my issue and came to the conclusion that the ECU is definitely cutting the boost due to my DAM dropping. I came to this conclusion because out of curiosity and running out of ideas to do... I reset the ECU. I noticed the DAM was .5 right off the bat(not sure if that's correct or not for a stage 1 tune) but anyways I did a few small pulls hitting full boost every time. I noticed after the third pull I did, my DAM dropped to .25. I did a full pull about an hour later and my DAM dropped to 0 immediately cutting my boost to wastegate pressure. From what I've read, and you told me it is due to knock or whatnot. Since I have this narrowed down... where do I go next? What would be causing the knock if all I have are the mods required for the stage 1 tune and it is indeed running the stage 1 tune. Also forgot to mention bad gas is out of the scenario because this is my third tank from a top tier provider and it does the same thing every time. Any further suggestions would be highly appreciated. Thanks again for reading this ~ Josh

Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
Hi again Zax,

I'm not sure you could give me any more knowledge on what to do but I've narrowed down my issue and came to the conclusion that the ECU is definitely cutting the boost due to my DAM dropping. I came to this conclusion because out of curiosity and running out of ideas to do... I reset the ECU. I noticed the DAM was .5 right off the bat(not sure if that's correct or not for a stage 1 tune) but anyways I did a few small pulls hitting full boost every time. I noticed after the third pull I did, my DAM dropped to .25. I did a full pull about an hour later and my DAM dropped to 0 immediately cutting my boost to wastegate pressure. From what I've read, and you told me it is due to knock or whatnot. Since I have this narrowed down... where do I go next? What would be causing the knock if all I have are the mods required for the stage 1 tune and it is indeed running the stage 1 tune. Also forgot to mention bad gas is out of the scenario because this is my third tank from a top tier provider and it does the same thing every time. Any further suggestions would be highly appreciated. Thanks again for reading this ~ Josh

Sent from my SM-G950U using Tapatalk
What do your fuel trims look like?

Assuming the ECU has been properly mapped to the mods on the car, my approach would be:
1. IF Fuel trims are very high, check for vac leaks or blown gaskets
2. IF cylinder roughness values high or CEL for misfire, check fuel injectors and fuel feed is OK, replace spark plugs
3. IF oil consumption is high, check compression and/or cylinder leakdown
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #7 ·
What do your fuel trims look like?

Assuming the ECU has been properly mapped to the mods on the car, my approach would be:
1. IF Fuel trims are very high, check for vac leaks or blown gaskets
2. IF cylinder roughness values high or CEL for misfire, check fuel injectors and fuel feed is OK, replace spark plugs
3. IF oil consumption is high, check compression and/or cylinder leakdown
I went out and did some data logging... not sure if you would be able to tell me anything. I noticed as soon as I WOT, you'll see the knock occurs, my DAM instantly drops, and it drops down to wastegate spring pressure. I also logged cylinder roughness and didn't see anything there. I logged the fuel maps as well and they seemed to be alright. I threw an after boostcut log in there as well and a idle log where the fuel seems to start doing something... no clue what it all means. Any more help would be amazing. And it doesn't seem to be burning any oil either, so I'm lost still stuck. Anything else helps..

Datalogs: https://1drv.ms/x/s!AumfbscUJRWJgYRfkH5O3d_T3M-n1Q



Sent from my SM-G950U using Tapatalk
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #8 ·
What do your fuel trims look like?

Assuming the ECU has been properly mapped to the mods on the car, my approach would be:
1. IF Fuel trims are very high, check for vac leaks or blown gaskets
2. IF cylinder roughness values high or CEL for misfire, check fuel injectors and fuel feed is OK, replace spark plugs
3. IF oil consumption is high, check compression and/or cylinder leakdown
I went out and did some data logging... not sure if you would be able to tell me anything. I noticed as soon as I WOT, you'll see the knock occurs, my DAM instantly drops, and it drops down to wastegate spring pressure. I also logged cylinder roughness and didn't see anything there. I logged the fuel maps as well and they seemed to be alright. I threw an after boostcut log in there as well and a idle log where the fuel seems to start doing something... no clue what it all means. Any more help would be amazing. And it doesn't seem to be burning any oil either, so I'm lost again.

Datalogs: https://1drv.ms/x/s!AumfbscUJRWJgYRfkH5O3d_T3M-n1Q



Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
Take a picture of your engine bay.

Exactly what map is flashed to the ECU?

Sent from my SM-G960U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
Take and post a photo centered above the passenger side strut tower. I want to see the rear of the turbo and the boost control solenoid.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #12 ·
Take and post a photo centered above the passenger side strut tower. I want to see the rear of the turbo and the boost control solenoid.
Okay I think I got a picture of what you needed, thanks again for all the help.


Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
This is going to be a tough road for you to vet out the problem.

If I were in your shoes, my first task would be to do a compression test on the motor. Leak-down is even better.

The car was obviously previously modified beyond the current state. You will want to put a heat shield on that turbo.

You said the restictor pill is in the vacuum line -- is the solenoid stock?

Do you know when the Timing belt and tensioners were replaced? It also wouldn't be a bad idea to check the static timing on the motor in case the belt has hopped a tooth.

It doesn't seem like a vac leak since your Fuel Trims are reasonable, nor would I think that it's a fueling problem. HOWEVER, if you are still looking for the problem after all of the above maybe it's a good idea to invest in a WBO2 sensor.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #14 ·
This is going to be a tough road for you to vet out the problem.

If I were in your shoes, my first task would be to do a compression test on the motor. Leak-down is even better.

The car was obviously previously modified beyond the current state. You will want to put a heat shield on that turbo.

You said the restictor pill is in the vacuum line -- is the solenoid stock?

Do you know when the Timing belt and tensioners were replaced? It also wouldn't be a bad idea to check the static timing on the motor in case the belt has hopped a tooth.

It doesn't seem like a vac leak since your Fuel Trims are reasonable, nor would I think that it's a fueling problem. HOWEVER, if you are still looking for the problem after all of the above maybe it's a good idea to invest in a WBO2 sensor.
Thank you for everything... I'll probably do those tasks in order. I don't think it'll be anything with the engine only because... (probably should have mentioned this in the start ) the short block is brand new. The previous owner must've ****ed something up somewhere.. anyways I'll take your advice, once again thanks for all the help and I will respond back when I find the issue...


Sent from my SM-G950U using Tapatalk
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #15 ·
This is going to be a tough road for you to vet out the problem.

If I were in your shoes, my first task would be to do a compression test on the motor. Leak-down is even better.

The car was obviously previously modified beyond the current state. You will want to put a heat shield on that turbo.

You said the restictor pill is in the vacuum line -- is the solenoid stock?

Do you know when the Timing belt and tensioners were replaced? It also wouldn't be a bad idea to check the static timing on the motor in case the belt has hopped a tooth.

It doesn't seem like a vac leak since your Fuel Trims are reasonable, nor would I think that it's a fueling problem. HOWEVER, if you are still looking for the problem after all of the above maybe it's a good idea to invest in a WBO2 sensor.
The restrictor pill was the first thing I checked for.. and it's there and the lines are routed correctly. The timing belt is also new along with the installation of the new short block. I have a whole list of stuff that was new... but the short block was basically the only thing new. All other external parts of the engine were reused.


Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
Thank you for everything... I'll probably do those tasks in order. I don't think it'll be anything with the engine only because... (probably should have mentioned this in the start ) the short block is brand new. The previous owner must've ****ed something up somewhere.. anyways I'll take your advice, once again thanks for all the help and I will respond back when I find the issue...


Sent from my SM-G950U using Tapatalk
Is it an OEM shortblock?

If not, that's your issue.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #17 ·
Is it an OEM shortblock?

If not, that's your issue.
Yes, OEM shortblock from a local Subaru dealership. The dealership I purchased the car from reassembled it... making me think they screwed something up somewhere but clearly I do not know what...


Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
That's wild. Makes me think the static timing should be the top of your list of things to check.

Beyond that, I'm afraid you're shooting well above my pay grade.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #19 ·
That's wild. Makes me think the static timing should be the top of your list of things to check.

Beyond that, I'm afraid you're shooting well above my pay grade.
I'm only 19.. can't really say I know how to check that. If it seems easy I'll do it, if not I'll have my mom's garage look at it I guess. But if I can't figure out what it is, should I take it to a garage, or a tuning shop..?

Sent from my SM-G950U using Tapatalk
 

·
Æternum
Joined
·
15,504 Posts
I'm only 19.. can't really say I know how to check that. If it seems easy I'll do it, if not I'll have my mom's garage look at it I guess. But if I can't figure out what it is, should I take it to a garage, or a tuning shop..?

Sent from my SM-G950U using Tapatalk
That's probably best. Try not to drive it until then.

Another thought -- might be worth replacing or checking the stock knock sensor. If it's loose and registering false knock, that could explain the whole issue. Normally I wouldn't think that would be the case, but since the shortblock was replaced perhaps it was reinstalled incorrectly.
 
1 - 20 of 21 Posts
Top