Knock Sensor - 2005 Legacy GT

[iNfEk]

If the IAM dropped to 0.875, it essentially means that it saw too many knock events on the map and decided to pull timing across the whole map. And as you can see, it still pulled some more timing even with a 0.875 IAM. But yeah, check for vacuum leak first.

Do you have an aftermarket air filter?

 

yup. its a hot air intake. cobb i believe thats on the car right now. idk if i have the stock air box. i'll need to check to see if the previous owner gave it to us.

[xt2005bonbon]

Did you have that aftermarket intake installed when you got tuned?

[iNfEk]

Did you have that aftermarket intake installed when you got tuned?

 

yup, i believe so. so the MAF scaling and such should be correct. i'll confirm. i suspect the tune or needing larger injectors since it's maxing out and causing lean condition but if you're saying it might be a leak thats worth looking into. i've changed a bit of vacuum hoses myself already.

[xt2005bonbon]

OK. That's good that you are tuned for it.

 

As for needing injectors, you're even running lean at super low load and idle, where injectors are definitely not pushed. So do check for vacuum leak first and see what happens.

 

Here is an easy way to check if you don't already know this procedure (check out the bold part):

 

Regular maintenance is the key to longevity of your forced induction engine. A major cause of stress to all turbo charged engines, especially MAF based systems are vacuum and boost leaks. As a turbocharger feeds air into a leaking system it begins to spin faster in an attempt to maintain the targeted boost level. This over spin creates decreased compressor efficiency and excess heat. Added heat increases the chances for knock and decreases power. In addition to hotter combustion the location of the leak will greatly effect the air to fuel ratio.

 

 

Most vacuum leaks originating between the MAF sensor and turbo inlet will lean out the mixture, as outside are is drawn into the system beyond the point of metering. While boost leaks after the turbocharger typically make a rich in boost as air leaks out. Boost and vacuum leaks can occur in the manifold or tgv area which generate lean fueling in low load (vacuum) and rich fueling when above atmospheric pressure. Leaks will also effect the ecu's function as it tries to trim fuel to meet demands based on its sensor feedback. Learned fuel trims will often be greater than +/- 8. The key to optimal performance and reliability is to regularly check for boost and vacuum leaks. This test can be very simple and accomplished without many tools or a compressor.

 

Leak Test:

You will need, a flat head screw driver and a plug for the intake 2.75” OD (aerosol can, spray paint etc will work). You remove your intake from your inlet tube, then insert the can into the coupler just in front of the inlet tube. Next you remove the vacuum source line from the by-pass or blow-off valve and blow into the source line (which connects to the manifold). Try not use above 5 psi because the inlet, pcv, and valve breathers will be under pressure and could pop off or generate a leak. The breathers normally do not see boost pressure. I typically blow into the line with my mouth (lungs) because its quiet and easier to hear air coming out of the system. Once all leaks are contained I blow into it and put my thumb over the hose for 3-4 seconds, then release my finger, and it should still contain some pressure and you can hear it hiss back out at you. A smoke test is another good way to locate leak sources but a smoke machine is needed.

 

Once all the leaks are sorted out its time to check the health of the tune. You will want to reset the ecu and warm the car up. You may now log idle and highway cruising. Observe the “A/F correction #1” and A/F learning #1” the total of these two should be less then 7%. Observe the DAM (dynamic advance multiplier) it should always be at 1.0 on a TA tune. Factory tune starts off at 0.5 and should rise up to 1.0. Email the results to your tuner! If this all looks good your now ready to do a full throttle log in 3rd or 4th gear. It is best to log a single run through part of the power band roughly (2500-5000rpm). No good reason to do multiple logs of the same conditions, especially if something is wrong. Your tuner may give you specific instructions of what to log depending the need. Email the tuner the results. Wait until they confirm is everything is correct. Typically, after the partial pull looks positive you will be asked for a full pull to redline. Followed by short pulls in higher gears. Driver must use judgment and drive responsibly in a safe place, while obeying speed limits laws, etc.

 

 

 

 

Tuning Checklist:

 

• Eliminate all vacuum and boost leaks(leak or smoke test).
  
• Reset ECU and warm up engine to operating temperature.
  
• Record a short log idle and cruising. Email to tuner.
  
• Verify DAM = 1 (or 16 on older wrx ecu's)
  
• Record 2500-5000 full throttle in a middle gear (3rd for 5spd/5eat, 4th for 6spd) and email to tuner.
  
• If full boost logs look positive you may drive normally (boosting once in awhile is okay) for a few days. Then record another idle, cruise, and WOT log and email to your tuner. This is to track the long term learning as learned values can be carried across the entire RPM band and can lean or richen the fuel mixture. This can also be done periodically to check up on health, and detect developing leaks.
  

[iNfEk]

OK. That's good that you are tuned for it.

 

As for needing injectors, you're even running lean at super low load and idle, where injectors are definitely not pushed. So do check for vacuum leak first and see what happens.

 

Here is an easy way to check if you don't already know this procedure (check out the bold part):

 

 

 

Now this is the type of help I missed from back in the day. I was thinking about pressurizing the intake when I get home after work. It's 10am here [emoji23] so I've got a ways to go.

 

I'll look over the procedure and verify. Thanks. I appreciate the help [emoji1417]

[xt2005bonbon]

No worries man. Hopefully, it's a simple fix.

[xt2005bonbon]

This post may also be helpful.

 

Hello there,

 

This quick writeup is hopefully going to help those who are unfamiliar with their engine bay help find and fix the more simple vacuum and pressure/boost leaks most common with these cars.

 

These pictures will be used as a loose reference for those searching to see a physical picture of what is described by most members that could be causes of leaks and struggles.

 

Intake/Vac leaks are one of the biggest headaches when tuning so the opportunity to go through the engine bay and check things out is always a plus.

 

The biggest thing to make sure when reading this is it assumes you have checked to make sure all worm gear clamps and such are tightened down at the airbox,turbo inlet, top mounted intercooler coupler to throttle body and to intercooler. These are simple things some people don't check first and causes a bunch of headaches for them.

 

This is a video showing what kind of leaks are possible and then pictures breaking down specific areas

 

https://www.facebook.com/video.php?v=377734489070626

 

1. This first picture is showing the turbo's wastegate hose *silver bell*, The turbo inlet *bigger black hose connected to turbo*, The turbo nipple hose and the turbo to intercooler mounting flange. These areas are prone to leak if the intercooler is not mounted properly and flush, The hoses are not seated on the hose barbs and if the turbo inlet has been chewed away by the clamp being tightened too much/not enough or just adjusted too many times because of age. If its oily and looks like rubber is coming through the worm gears section of the clamp its probably leaking.

 

http://legacygt.com/forums/attachment.php?attachmentid=200133&d=1420422748

 

2. This next picture is part of the next picture as well when it comes to descriptions. These intercoolers can leak from the plastic end tanks once they have aged OR are pushed at higher boost levels. The aluminum "fingers" start to fold up and the black plastic end tank starts to move away from the core which causes leaks. This is pointing at the underside of the core to explain it can leak from the bottom as well as the top.

 

http://legacygt.com/forums/attachment.php?attachmentid=200134&d=1420422748

 

3.This picture shows what was discussed in the last picture which is leaks at the intercooler to end take mounting area. These "fingers" can start to fold up over time because of age or being ran at higher boost levels and cause the end tank to separate from the core. If you look closely you can see where oil is escaping in the boost vapor and actually causing a spot where the intercooler is leaking. This is a common issue with this models intercooler.

 

http://legacygt.com/forums/attachment.php?attachmentid=200135&d=1420422748

 

4. This next picture is on the drivers side of the intake manifold between the two intake manifold runners. This is another vac line that can pop off so its good to check and ziptie. This also points at the area you might see an intake manifold gasket or anything leaking related to the tgv assemblies.

 

http://legacygt.com/forums/attachment.php?attachmentid=200136&d=1420422748

 

5. There is a lot going on in this area so it needs to be checked and ziptied/clamped as best as possible. This is at the turbo inlet area to the left side of the alternator. This is where the Stock electronic boost controller mounts and there are a lot of lines in this area.

 

http://legacygt.com/forums/attachment.php?attachmentid=200137&d=1420422748

 

6. This next pic can be a little confusing but most of the arrows are pointing toward the lines coming to and from the blow off valve. These need to be free of obstruction and connected tightly. Also make sure the gasket is in place on the bov if equipped. The arrow pointing under the intercooler is actually supposed to be pointed at the throttle body coupler and the fact that sometimes to get to the clamp closest to the throttle body you may have to go from under the cooler. There is a plastic sleeve on the stock throttle body hose that's prone to leak and can cause strange high pitched sounds when pinched open under boost. This has been said to be removed without issue but some say its very hard to get it sealed without it because of the design.

 

http://legacygt.com/forums/attachment.php?attachmentid=200138&d=1420422748

 

7. This next pic was used from a google search as I couldn't find a good lighting pic to demonstrate its location best. This is conneted right near the center of the rear of the intake manifold right under the top mounted intercooler. Its very hard to get to with the intercooler in place but is well known for popping off and causing people hassles. This can be ziptied or replaced with a barbed T fitting *one is supplied by a forum vendor turkeylord*.

 

http://legacygt.com/forums/attachment.php?attachmentid=200139&d=1420422748

 

This writeup is designed to help and the more comments and such people can provide will help others in their searches for leaks and hassles. Always keep in mind the age of the vehicles and that vacuum lines can crack or wear through with contact so the leak may not always be at one end of the hose either.

 

Hope this helps and bump it up to the top for others if you like the info

 

Dave

[iNfEk]

This post may also be helpful.

 

yup, that's the thread i was referring to. pretty good info and unfortunately i'm getting ready to take a plane to the outer island shortly so won't be able to check anything till i get back tomorrow evening or so.

 

keep you posted and again thanks

[iNfEk]

Sigh. Found two leaks. One was stupid and because I didn't put a hose clamp between the turbo Inlet and MAF hose and the other was found through this blowing method. Found a leaky intercooler.

 

Getting +13% bank 1 A after a reset and about 10 minutes of idle . I'm gonna go for a drive and see if the other areas are affected. IAM was 1 like normal.

 

I forgot to take a screenshot of the idle =\

 

This is after doing 3 third gear pulls from about 2k-5500 RPM. I believe the IAM changed to 0.875 due to idle trim percentage.

 

[xt2005bonbon]

So it looks like you still have some vacuum leaks.

 

Do you have the stock intercooler? If yes, you might want to 'bulletproof' it. See this: http://legacygt.com/forums/showthread.php/bullet-proof-tmic-kits-189608.html

[iNfEk]

So it looks like you still have some vacuum leaks.

 

 

 

Do you have the stock intercooler? If yes, you might want to 'bulletproof' it. See this: http://legacygt.com/forums/showthread.php/bullet-proof-tmic-kits-189608.html

 

 

 

yup, the intercooler is leaking on the passenger side end tank on the front side of the intercooler

 

https://vimeo.com/165609538

[xt2005bonbon]

Yeah that's definitely leaking and that is a common location for it. So definitely look into "bullet proofing it". How much boost are you running? What is your max target boost?

 

Although now that I think about it, if the intercooler is leaking air (and not sucking it), the ECU would then reduce fuel delivery, since air is escaping before entering the intake. So technically your trims would get negative and not positive... Strange.

[xt2005bonbon]

When you were tuned, did they make sure there were zero boost/vacuum leaks?

[iNfEk]

Yeah that's definitely leaking and that is a common location for it. So definitely look into "bullet proofing it". How much boost are you running? What is your max target boost?

 

Although now that I think about it, if the intercooler is leaking air (and not sucking it), the ECU would then reduce fuel delivery, since air is escaping before entering the intake. So technically your trims would get negative and not positive... Strange.

 

I honestly went through everything including blowing into the hose and that's how i found this leak actually. everything else previously was zip tied or secured accordingly. I use a industrial air craft zip tie gun so it's tight LOL.

 

I believe the target and max is 14.7-15PSI nothing too crazy right now since it's mostly stock.

 

I honestly fixed a shit ton of problems on this car. see that blue bolt head for the turbo. that was stripped out and had no threads on the turbo side before i got to it. rethreaded and now it seals. so much half ass shit was done =\

[iNfEk]

When you were tuned, did they make sure there were zero boost/vacuum leaks?

 

I wasn't around before that so I wouldn't know. i assume no. but i've fixed a bunch of problems though =\

[xt2005bonbon]

mmmh. So what aftermarket parts you have again on this car?

[iNfEk]

mmmh. So what aftermarket parts you have again on this car?

 

 

 

As far as the engine, turbo inlet, Grimmspeed 3 port, Cobb intake, up pipe, turbo back. AP3 with custom tune.

 

So not much. Everything else is stock. Contacted the tuner before posting all the stuff and he agrees seems like a leak. The last learning view I pulled before getting into work shows this:

 

 

It was correcting itself though at one point then it changed =\

[xt2005bonbon]

I see. The other fields are still showing low correction simply because you probably have not driven much in these load/rpm ranges.

So, I'd fix the TMIC first, recheck for leaks, and see what happens. Until that's done, I would not push the car and avoid boost.

[iNfEk]

I see. The other fields are still showing low correction simply because you probably have not driven much in these load/rpm ranges.

So, I'd fix the TMIC first, recheck for leaks, and see what happens. Until that's done, I would not push the car and avoid boost.

 

 

 

Yeah, I've been trying to avoid boosting as much as possible but my gf drives this car too so I have to remind her lol

[iNfEk]

So weird problem.... Or not....

 

Took the intercooler off. Saw the separation of the intercooler and end tank used similar procedure like the BP mod to reseal it again. Stupid fingers broke! Ugh!!! Got some high temp sealant I use for my valve covers that's oil resistant etc. let it sit the required 15 minutes. Install TMIC and button up everything. Cap the intake and blow into the BOV/BPV feed line like before after spraying soapy water.... I get pressure building and air rushing out of the line I'm blowing into. So I blow in again and check everything. Same thing. No bubbles and same pressure building. I then blow in again till I can't anymore and cap it with my finger. I hold for a little while then I release and air comes out!

 

I reset the ECU earlier and did an idle for like 10-15 minutes. Still getting +15% at the end through incremental step ups.

 

I cannot hear any air coming out of any vacuum lines...etc either.

 

I wonder if I'm having a MAF problem. I had buttoned up everything and plugged back in the MAF. started the car up and it was super rough idle and two CEL codes present. The one for MAF being unplugged and one for high IAT. I unplugged and replugged it in again a few times and started it up after resetting the ECU again and it started. Idle was bad as expected due to being reset so I watched the AFR coming from the factory sensor. It hung at 15 and progressively went down as the idle went down normally from 1k to 700-800RPM at normal operating temperature. No CEL this time and I kept watching the fuel trim A and it kept rising over a span of 5 minutes or so and maxing out at 15%

[iNfEk]

Found another issue...

 

 

Used my STI o-ring which is supposed to be 32mm OD x 28mm ID x 2mm thick and idle seems better though I'm still getting 15% after about 10 minutes of idle so in A. Shit

 

Did some driving around and not getting +15 in A-D anymore just in A & C. B & D have small corrections at the moment.

 

Maybe it's the tune?

 

 

EDIT:

 

after getting home late last night I noticed the ECU put out a CEL for lean condition but the IAM didn't change to 0.875 like it was prior. Also no knock showing either.

 

 

 

I've contacted the tuner to see what he says regarding the matter. Any ideas?

[xt2005bonbon]

Do you have a friend who has the same car as yours? If yes, you could swap MAF sensors to check if yours is still working right.

 

Also, have you ever changed your intake manifold oring gaskets? There have been several people reporting a 'system too lean' due to these gaskets not sealing up properly. You could always check them by spraying some maf cleaner around the gaskets during idle and see if the idle changes.

[iNfEk]

Do you have a friend who has the same car as yours? If yes, you could swap MAF sensors to check if yours is still working right.

 

Also, have you ever changed your intake manifold oring gaskets? There have been several people reporting a 'system too lean' due to these gaskets not sealing up properly. You could always check them by spraying some maf cleaner around the gaskets during idle and see if the idle changes.

 

 

 

I swapped gaskets and MAF with my STI and though the readings and changes were quicker the result was the same.

 

No I haven't actually but when troubleshooting I did shoot carb cleaner in that area with no change a while before all these issues. I can probably check again.

 

Only thing is. If I did have a leak wouldn't I get a loss in pressure building vs it building up if there was a leak there?

[xt2005bonbon]

When you mean a loss in pressure building, you mean when you blow through the bpv hose? If that's what you mean, then I don't think that method will find leaks there since the throttle body plate would be close.

[iNfEk]

When you mean a loss in pressure building, you mean when you blow through the bpv hose? If that's what you mean, then I don't think that method will find leaks there since the throttle body plate would be close.

 

 

 

Oh that's right. This is why I don't like DBW much. But the throttle plate should be open in idle though. I'll check it again and report back. Thanks.