Did you do an actual BLT? Or just check lines.

Be sure to update your profile as far as modifications. It helps to know what turbo you are running and all that kind of stuff.

To me, that ''hissing" noise you are hearing, is probably a boost leak. I had a leak like this also, could hear it just not see it. To be running 7psi on stock wastegate pressure is not right. That also makes me believe its a leak. It doesn't seem like a huge one though if you are able to build it up to 12-14. How exactly did you perform your boost leak test? A visual inspection is not sufficient when doing a boost leak test.

Just because you have looked over the vaccum lines does not mean there is not a leak. There are many other places that can be leaking. Lower intercooler piping, upper intercooler piping, the inter cooler itslef, j-pipe flange, blow off valve, throttle body, throttle body elbow, intake manifold, injectors, and many others. The list goes on.

Here is a good video for reference on boost leak testing. Spray bottle and soapy water are your friend. Be sure to check anything and everything that has to do with boost/vaccum.

http://www.youtube.com/watch?v=fdjadhUP1u4

Depending on where the leak is it can effect the car in different ways. What I've noticed is, a leak after the TB will be more noticeable at idle than when boosting. For example you may get a really low idle with a leak after the TB, but while boosting the turbo will just work harder and you're still able to make full boost. A leak pre TB will effect how much boost you can build more than the car will be effected at idle. After you find your leak and fix it, be sure to remember to back off your MBC before you drive.

Thanks guys il give this a shot in the next few days...

I dont know if this is the case with you, but when I put in my MBC the rubber was stuck so even though i was screwing, my psi wouldn't change, once I found out it was stuck i moved it by hand and then it started to work.

sounds like the MBC is stuck or the spring isnt doing what it should....

Its not the mbc.. Iv had like 3 different ones on the car and same result with every single one

check to see if your MBC line is trapped somewere, i had mine over top of the intake and it didin't look like it was trapped, but it was.. so i put it under the pipe and was good after that.

Have you checked for a leak around your blow off valve or checked to see if it's properly functioning? My friends wouldn't boost properly until he got a new BOV.

7psi does seem sorta low for stock even aswell. my gsx ran on average 10psi stock. Check lines id say and could it possibly be the flapper on wastegate isnt fully closing so it wont let it spool fully?

Check the WG flapper and where it meets the WGA arm. Sounds like it's hanging open.

Stock Mitsu actuator has a cracking pressure of 7psi and full open at 10psi.

FWIW I went 13.6 on WG pressure on a 16g, creeping to around 17psi at redline.


Do a good BLT. Injector seals where the injector meets the intake mani like to dry up, harden, and crack. Mine fell apart on removal.

BISS Screw, although it shouldn't keep you from building boost since I shot mine out and held 20psi to redline still..

Check if your brake booster line has a check valve in it still. Go into boost and pump the brakes up until hard and then let off. It should suck the pedal right down.

Checked the turbo for shaft play? My 16g I'm on had almost .5" of in/out so I can comp wheel damage but it still spooled fine and didn't burn any oil..

standard235 said:

Check the WG flapper and where it meets the WGA arm. Sounds like it's hanging open.

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That's what it sounds like to me too. I would remove the wastegate arm and try working the flapper open and closed to make sure it moves freely. If it does move freely make sure it is closing all the way when the rod is hooked up. Good luck

Rod is tack welded to the flapper so im guessing thats probably it..

It sounds like a classic boost leak, or more correctly, multiple boost leaks. Have you ever done a boost leak test? I've been doing boost leak tests for almost a year now and I'm still finding and fixing leaks and every time I'm holding more and more boost and the car is running better and better. A boost leak test is not a one time thing, its something you will be doing for the rest of your DSM life.

Someone mentioned your BOV, my 1g BOV was opening at 10 psi and I wouldn't hold more then that on a boost leak test. I just recently "crushed" it and now I can hold up to 15 psi from the turbo inlet.

I have personally fixed boost leaks on my DSM at the fuel injector seals, throttle body shaft seals, throttle body gasket, j-pipe, nipple on j-pipe, BOV flange, boost gauge source, the compressor housing o-ring, intercooler pipe couplings, intercooler pipe weld, and the BOV itself. Originally I would boost 12 psi. BLT from the throttle body would hold 0 and from the turbo inlet 0. Now it boosts 14 and holds 20 from the throttle body and 15 from the turbo inlet. I'm still working on it.

A parting tip, start doing your BLT's at the throttle body inlet and keep keep doing them there until you get it to hold your desired pressure. Once you are happy with how it's holding from there, then work your way back to the turbo inlet.

Hope this helps!

Found the major problem.. I was messing around under the hood today just kinda wiping things down and found that under the coolant temp senser on the thermostat housing there is a senser with 2 vacum lines going to it that both t into 2 more. Well all 4 lines where broke off those t's. So until i have time to trace them back i just plugged them and left the senser un hooked. Zero'd the mbc out and slowly dialed it in and now im at a steady 15psi with no issues. Hopefully sunday il have time to fix things right. Now my question is what is this senser for? Car seems fine without it but i dont like leaving things unhooked un less it really is un needed or is for emissions or something.

If it's what I'm thinking it is, it is for the a/c.

Tyeler18 said:

If it's what I'm thinking it is, it is for the a/c.

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No, actually you are thinking of the A/C thermoswitch on the upper portion of the throttle body. It has 2 wires going to it (One is a green wire with a yellow strip that runs to the A/C sightglass and the other is a black wire with a green strip that runs to pin #7 on the ECU) but no vacuum lines. It's only purpose is to shut off the A/C if the car starts to overheat while the A/C is running.

Car_guy_09 said:

on the thermostat housing there is a senser with 2 vacum lines going to it that both t into 2 more. Well all 4 lines where broke off those t's. So until i have time to trace them back i just plugged them and left the senser un hooked. Zero'd the mbc out and slowly dialed it in and now im at a steady 15psi with no issues. Hopefully sunday il have time to fix things right. Now my question is what is this senser for?

Click to expand...

It is the Thermo Vacuum Valve, part of the EGR system (which is part of the emission as you guessed). Two vacuum lines run from the throttle body to the thermo vacuum valve and then over the EGR valve. You can safely remove the entire EGR system by following this diagram:

Before:


After:

(Except don't 'T' your MBC into the BOV line, run it from the compressor housing/j-pipe).

Car_guy_09 said:

Found the major problem.. I was messing around under the hood today just kinda wiping things down

Click to expand...

And for the record, this is NOT a boost leak test. You still need to do start doing boost leak tests to get the most out of your car.

Hope this helps!

When you suspect a boost leak you most do a full proper boost leak test to ensure where you're leaking from! It sounds to me as if you have a hard to fine leak somewhere on a vacuum like most likely behind the intake manifold.. or possibly you BOV is slightly open under boost due to a worn diaphram or something!

Do a BLT and let us know the results to further properly assist you!!

EDIT:

Disregard my post!

Sorry i over read the your last post, stating that you found and fixed the boost leak!

Also i would have never suspected your problem due to that fact my EGR is Deleted haha i have no personal experiance having a DSM with the EGR!!

wkmitsu said:

Depending on where the leak is it can effect the car in different ways. What I've noticed is, a leak after the TB will be more noticeable at idle than when boosting. For example you may get a really low idle with a leak after the TB, but while boosting the turbo will just work harder and you're still able to make full boost. A leak pre TB will effect how much boost you can build more than the car will be effected at idle. After you find your leak and fix it, be sure to remember to back off your MBC before you drive.

Click to expand...

sorry to jump into this with my own question but this post got me thinking. i have a sort of rough idle, and trying to get into boost my car has a slight cut out til it builds about 14lbs. someone else told me it may be boost leak. where exactly should i check for this?

mathewdylang said:

sorry to jump into this with my own question but this post got me thinking. i have a sort of rough idle, and trying to get into boost my car has a slight cut out til it builds about 14lbs. someone else told me it may be boost leak. where exactly should i check for this?

Click to expand...

http://www.dsmtuners.com/forums/new...ester-merged.html?highlight=BOOST+LEAK+TESTER

if you are using a 14b i dont think that from the factory it runs any more than 7lbs of boost