Boost leak tested, still having gas problems.

[TAndrus]

So a while back I posted about my gas problems. I was told to:
a) Recirculate my bov - Check
b) New spark plugs - Check
c) New wires - Check
d) Boost leak test - Tried today

Well.. I finally got a tester, hooked it up to my little T25 and tried to put some air in the system. The compressor wouldn't put anymore than 10psi in, then just was just pumping but kept it at a stand still on the gauge. I couldn't hear any leaks other than the air pumping into the system. What could be the problem..?

Also, I kept telling myself, remember to plug the MAF back in and mistakingly that was the ONLY thing I left unplugged... So now I think it resulted in a check engine light, or could it be something else? I don't have any data logging equipment because I've been told running on a stock system it's not really needed. Any help will be appreciated, thanks!

 

[stomp]

Try using a spray bottle with soap and water to find where the boosted air would be leaking as for by all couplers ,blow off valve, injectors ,try resetting(unplug negative) your battery for about ten minutes to clear the code and see if it comes back on or not

 

[tlikethedrink]

what kinda MPG are you getting now?
may not be leaking that much and it would be harder to find with such a low test psi. usually you wanna test it for more than your actually gonna push. that way you know your good.

 

[-TunedDSM-]

Do you have an aftermarket boost guage? The stock gauge is not mechanical and will not register the pressures. Testing with a spray bottle of soapy water is a great trick to pinpoint leaks as stomp stated.

As far as your check engine light, is it still on after plugging in the MAF? If it is, go over to autozone and have them pull the code for free.

Onto your gas mileage problem, you may want to check your front 02 sensor. Improper readings from a faulty sensor could throw off the mileage. Report back and we will take it from there

 

[TAndrus]

Stomp, So spraying the injectors, blow off valve, and the couplers would be the only places..? Which couplers are you talking about. Sorry, I'm a total noob when it comes to this stuff.

tlikethedrink, I'm getting anywhere from 14mpg - 16mpg. When I bought the car I was unaware of this and as a daily driver, I really need to get some better gas mileage. And the issue wasn't that the compressor would not create the pressure because I've used to to fill tires to 30+psi, but rather, it was just not increasing past 10psi when going into the system and I'm not sure why.

-TunedDSM-, Yes I have an autometer phantom boost gauge. I was reading the PSI that was going into the system from the gauge built onto my compressor head thing. Where exactly would you spray the soapy water because I'm not exactly sure what could all leak. The MAF is plugged in now, and I'm still having the error. We've got an autozone so I'll have to stop by. Regarding the O2 sensor, I'm hoping to take a look at it soon. I just got an A/F gauge that I can splice into my stock sensor, but I'm thinking of replacing it before I hook the new gauge up. What O2 replacements would you suggest?


Thanks a ton for the responses. Hopefully I responded to your comments well enough to provide info to get somewhere. Thanks again! If you need to know anything else, I'll try to answer as best as I can.

 

[-TunedDSM-]

I would spray anywhere a seal is made (couplers/clamps/etc.). Also make sure to check that all your vacuum lines are connected.

The front 02 sensor is going to be the one your worried about. The rear 02 doesnt really do much of anything. As far as the A/F gauge, I wouldnt bother installing it. They are not very accurate, consider picking up a wideband.

Definitely get that code pulled and let us know.

 

[stomp]

As for not running any data logging equipment,I beg to differ because it will save you money and time in the long run. Put your boost leak tester back on and put about 17psi of air through and have someone watch your boost gauge it should leak down slowly ,mine takes about 50 seconds from about 18psi to O, while the air is leaking spray soapy water around places that air could escape like at the blow off valve ,around pipe couplers,around injectors throttle body ,pcv valve, biss screw located on top of your throttle body and if you still have the stock intercooler piping spray all of it ,mine had many leaks so I up graded to metal piping,I'm pretty sure your cel light is on because you forgot to plug your maf in before you started the car but it doesn't hurt to get it checked out just go somewhere it's free like they stated (autozone) but it doesn't hurt to reset your battery and see if it comes back on or not.

 

[kenamond]

I'll try to rattle off the normal boost leak sources. Others: feel free to add what I missed.

• TB gaskets (both sides of the throttle body - between the TB elbow and TB and between the TB and IM)
• Injector insulators (between injectors and head)
• BOV gasket
• SMIC (it may have corroded or had a rock go through it a bit)
• Couplers: LICP both ends, UICP first half both ends, 2nd half both ends. Also, the couplers can have holes in them.
• Throttle shaft seals (little o-rings sealing each end of the shaft on the throttle butterfly valve)
• BISS o-ring (Base Idle Set Screw which has an o-ring around it and is threaded into the TB)
• PCV valve - This is SUPER DOOPER COMMON! It stops serving its "check valve" role after a while. Replace with OEM, not (NOT (NOT))) Autozone/Carquest/Advanced Autoparts. Those WILL NOT (WILL NOT) work. Or you can read the thread called "Stupid PCV question" posted by FORMONTOYA and find out about an alternative (read it all...as long as it is).
• Intake manifold gasket (between the IM and head)

There are other sources of leaks that are trickier to find. Bad compression will bleed off air in the form of blow-by. Also, leaking intake valve stem seals will leak boost from the intake ports up into the head (under the valve cover). That's not super obvious, but the intake valve stems go through the "roof" of the intake ports, so they do see boost and can leak boost.

Do the boost leak test on a FULLY WARM motor with the oil fill cap off the valve cover. A warmed up motor causes things like rings and valve stem seals to seal better...much better. It makes a huge difference.

If your compression sucks, I don't know what your leak-down rate should be. On my car with 172,172,172,165 compression, I hold 20psi and leak 1psi every few seconds and claim that I have "no" boost leaks (even though my BISS leaks a tiny bit ).

First off is to test on a warm motor if you didn't do that. Then if it still won't pressurize up to 20psi, have someone *listen* for hissing. The soapy water trick doesn't work for big leaks - it just pops the bubbles. Fix all those big leaks.

Part of this should include unscrewing the PCV valve from the valve cover but leaving the vaccuum line connected to the PCV valve and the intake manifold. Pressurize and see if it's leaking in a gawd-aweful manner. Replace (WITH OEM FOR GOD'S SAKE!) if needed. And by OEM, I mean go to a Mitsu dealership and order one or buy one if they have it in stock. Tear open the bag at the counter and blow on the end that connects to the vaccuum line (not the bronze end) and see if it leaks...and don't buy it if it does.

Once you can get more pressure in there and have fixed the big leaks, do the soapy water trick. Get a spray bottle and put a super-soapy water/dishsoap mix in it and spritz it at all the couplers, base of the injectors, BISS, TB gaskets, etc. I would start at one area, spritz, pressurize, look for bubbles. Then move on to the next part.

Then pressurize and while it's bleeding down pressure, look for bubbles forming.

If big leaks are still a problem, you can divide and conquer. Disconnect the upper UICP from the TB elbow and boost leak test there (on the TB elbow, not the UICP, you ninny!). If that's not the problem, you know it's between there and the compressor inlet. You get the idea, though.

Fix all of your leaks. It adds power in addition to increasing mileage.

And if you don't know what some of the parts are I've mentioned, please search to find the answer. You can also make good use of the virtual tour page.

There ya go!

 

[TAndrus]

-TunedDSM-,
It's funny that you mention vacuum lines because I've had a horribly anal idle. Sometimes it's high, sometimes it's so low that the car wants to die. I'll make sure to check that when I do the next test.

I'll see about replacing that front sensor. I was aware that the A/F gauge isn't really completely accurate, but it's better than nothing (I only payed $30). I'd get a wideband, but it's just really not in my budget right now.

Stomp,
I'll try and do that. It looks like I'll have to get a better air compressor because 18psi wouldn't even go into the system. Is it just really soapy water that you use?

Kenamond,
Wow, thanks for the whole run down. I thought I had heard somewhere about removing the oil cap, but I couldn't find anything on here before I went out so I just did it with it on. Hopefully that's not too harmful? I've got all stock piping, which could be a bad thing. I've been told to get some hard pipes. I need to test my compression, I just haven't had a chance. I should have done all of this before I bought the car, but I was too exited to even think further than the whole giving him the money and I've got a fast car thing. A friend of mine who works on cars said he thought he heard a misfire but he wasn't sure. Would I be able to find this out with a compression test? I looked to see what that PCV valve was and that's an area I've got a lot of clicking coming from so possibly that's a leak. I've got a video I took a while back. There are two separate clicks, I'm pretty sure one is a lifter tick, but the other could be the leak: Video.

 

[kenamond]

Wow, thanks for the whole run down. I thought I had heard somewhere about removing the oil cap, but I couldn't find anything on here before I went out so I just did it with it on. Hopefully that's not too harmful? I've got all stock piping, which could be a bad thing. I've been told to get some hard pipes. I need to test my compression, I just haven't had a chance. I should have done all of this before I bought the car, but I was too exited to even think further than the whole giving him the money and I've got a fast car thing. A friend of mine who works on cars said he thought he heard a misfire but he wasn't sure. Would I be able to find this out with a compression test? I looked to see what that PCV valve was and that's an area I've got a lot of clicking coming from so possibly that's a leak. I've got a video I took a while back. There are two separate clicks, I'm pretty sure one is a lifter tick, but the other could be the leak: Video.

The oil cap removal is just so you don't accidentally overpressurize your crankcase during a test. Oil return passages connecting the top of the head to the crankcase will let PLENTY of air through with the cap off. If you're all stock and were only putting 10psi in, you're probably just fine.

Misfire could be plugs or wires. Get NGK BPR6ES plugs ($2/ea at NAPA) and ignore anything anyone tells you otherwise: "That's not what your car needs...blah, blah, blah" Just thank them and ask for these plugs anyway. Gap them to 0.028". If that doesn't fix the misfire, try new wires.

PCV valve unscrews easily enough. Then do the leak test and check for air coming out the tip. If reinstalling it, don't overtorque or you'll strip the *aluminum* valve cover.

Lifter tick can be fixed (see my tech article), but it's a bit more involved than changing the oil.

The intercooler pipes aren't bad on the 2g *except* the first half of the UICP (between the intercooler and the BOV). But if you upgrade that, you'll probably end up having to upgrade the air filter (the stock filter box will get in the way) and BOV (the upgraded pipes are usually flanged for a 1g BOV or a Greddy BOV). If you remove your air filter box, you'll see why we all say that the 2g UICP *stinks*.

Good luck, and fix those boost leaks!

 

[Semprini]

As far as boost leak goes.. Is it possible, or normal, that itll either, leak sometimes and the rest of the time not... or leak all the time, just a very small amount, then sometimes a whole lot.

Every now and then I would notice that as it boosts up its actually pulling less (a lot of hesitation) then before the boost even kicked it. When this happens I immediately let off of the gas, then accelerate again and its fine.. its boosts normal and pulls hard. Now I havent done the test yet and I do plan on it, but I just wanted to get a few opinions first, bc this doesnt sound the same as everyone describes boostleak


Thanks

 

[TAndrus]

Bringing this back from the dead...

I have boost leak tested, filled my tires to the proper pressure.. done everything! It's still not fixing my gas problems.

 

[DougR]

Bro. soapy water work well and all. But if you want to know the Super secret way of finding leaks?

Use Bubble maker stuff that kids use to blow those big ass bubbles... mix it in some water and HOSE that engine. Trust me if there is even the smallest or largest leak, you will have the best bubble show on the planet!

Every Vacume line, your fuel pressure regulator, The T fitting you used to install the boost guage.
EVERYTHING! even under the TB. Spray down that EGR. Its Very well hidden and causes ALOT of leaks that 80% of tuners dont find!
Just carefully check All hoses for splits and cracks... even those that have the Extra rubber cover on them for protection, they like to burst under that cover. Due to dirt and nasty stuff getting between them and rubbing a hole or just plain drying out, due to no armor-all or equivelent getting to the hose.
And once you are done. use small black zip ties to clamp Every single hose end you can find!!
and as stated above, open that oil filler cap. Dont be a noob like me. and cause 3 oil leaks by over Pressure the crankcase! Did this the first day I got my talon.. Oops!

My first impressions of your problem made me instantly think of a friend's car. who had dissconnected his FP regulator, then never hooked it back up... needles to say, he had one hell of a vacume leak, and like 5 MPG.

Here is another method to finding a couple reasons for bad gas...
Dead Injectors! normally they are so loud, you can hear if one is not working. but sometimes you can't. heres a simple test.
unplug them and test one at a time, and listen for changes in engine RPM.. If NO change, you have a dead injector... which causes the ECU to compensate by Dumping Loads of fuel into the Working Injectors, To make the engine run somewhat right.
This can cause VERY poor MPG. and most ppl dont even know they have been driving on a bad Injector for months.



DougR

 

[TAndrus]

Here is another method to finding a couple reasons for bad gas...
Dead Injectors! normally they are so loud, you can hear if one is not working. but sometimes you can't. heres a simple test.
unplug them and test one at a time, and listen for changes in engine RPM.. If NO change, you have a dead injector... which causes the ECU to compensate by Dumping Loads of fuel into the Working Injectors, To make the engine run somewhat right.
This can cause VERY poor MPG. and most ppl dont even know they have been driving on a bad Injector for months.

DougR

Wow. That could be something. I'm pretty sure I'm running on the stock injectors (@122k miles now). They click fairly loudly from what I can tell. I'll have to try that. And I'll boost leak test again since it's warming up. It blew being out in the 10 degree weather (car was warm though) trying to test for leaks.

 

[kenamond]

Wow. That could be something. I'm pretty sure I'm running on the stock injectors (@122k miles now). They click fairly loudly from what I can tell. I'll have to try that. And I'll boost leak test again since it's warming up. It blew being out in the 10 degree weather (car was warm though) trying to test for leaks.

Did you find and fix all of the boost leaks? You should be able to pressurize to 20psi and leak down 1psi every few seconds.

 

[TAndrus]

Did you find and fix all of the boost leaks? You should be able to pressurize to 20psi and leak down 1psi every few seconds.

I tested, and really, I found no leaks what so ever.

Edit: Heading out to test again, I'll report back soon

 

[TAndrus]

Okay, BISS ring, and the backside of my BOV leak. I still can't seem to get more than 6-10psi in the system though. I tested the compressor and it gets far more than 20psi on other things (tires, ect). I'm not sure of the problem now.

What can i do about those two leaks now though? Are they really enough to cause such a drop in gas mileage.

Also, There was a little bit of oil in the bottom of the air intake where the mouth of the turbo is... Is this normal? Here's some pictures of stuff:

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Here's also a video of me taking it out at wot just a minute ago. I don't see any leak down on the boost.. So I don't know what's up.
<embed width="430" height="389" type="application/x-shockwave-flash" wmode="transparent" src="http://smg.photobucket.com/flash/player.swf?file=http://vidmg.photobucket.com/albums/v251/Badboy89/boost.flv"></embed>

 

[DougR]

Long reply for ya!

Yess the oil is normal. You have a Turbo. there will Always be leaks past the rings which is Blowby. Creating positive crankcase pressure, thus pushing oil residue, aka fog up into the PCV system.
This collects and moves, until you see it as oil in the mouth of the turbo. and along the entire intake track. This is fixed by a Catch can. I just made one from HDR- home depot racing for 20$. which is a direct copy of this.
Except I chose to use a barbed fitting on the drain and a 2 foot piece of Clear Hose with a Oring seal ball check valve at the end. This Keeps ALL oil Out of the CC, where it could be picked back up by Vacume. AND allows you EASY to see when its time to drain. simple as if the oil is getting close to the CC drain it!
http://www.saikoumichi.com/OCC_explanation.htm

Look here for a In-depth look at the the correct way to solve the oil in turbo problem.
http://www.dsmtuners.com/forums/newbie-forum/286353-catch-can-3d-design.html

Now onto that BISS leak.. Any auto parts store or hardware store that sells O-rings will have what you need.
Pull out that BISS. First Screwing it Down into the TB and Counting How many turns it takes to LIGHTLY seat the BISS screw. GENTLY!!! you can totaly screw the pooch here. The Biss is Soft brass.. The TB is Soft aluminium! Very Gently Seat the BISS! I cannot stress it enough!
If you over tighten it. it will Flare the Aluminum seat and Dent the brass BISS screw. And will NEVER Meter the air right again!

Ok so you got it out. pull that oring off and match it with a Black ring from the stores listed above. Im positive someone here has the part number and or size you need. heck you could find it with in a minute or so "searching".

Put on new oring and seat the BISS as described above.. GENTLY!!!! Then back it out the number of turns you Wrote! down... This will get you in the hunt for that Correct idle speed. warm car. check idle.. adjust screw. you're done.. O one more thing. either buy the plug that covers the BISS. or fill it with Black RTV. this will make certain it never backs out or moves out of adjustment, along with never leaking again.

As of the BOV leak. you're on you're own there. as I have no personal experiece with that brand BOV. I will tell ya to Reassemble it with small amount of blue loctight on ALL threaded parts! this will seal them. and IF it has any kind of Rubber diaphram, use a silicon based grease to Lube up the outer edge of the diaphram. So that it seals against the Aluminum BOV body. That will prevent leaks for ALONG time..

FYI. those Vacume lines are Factory lines. Replace them completly or ZIPTIE the ends! (I did Both) You will find that most of them pull off easily or Rotate on their fittings. which is a LEAK! even if you dont make it leak under 15PSI. it will still Leak slightly once Driving and or pulling vacume. IT WILL LEAK! Or blow off once you fix the Boost leaks you have already found. Trust me i found out the hard way after replacing my BOV. had 4 lines pop off one at a time while driving... Luckily its a DSM and Always has Zipties in the Glove box WTF .

Anyways.. Good Luck



DougR

 

[kenamond]

BISS o-ring is a #5. You can buy the Mitsu version, too, but you'll have to go check the VFAQ article for the part number. It's under the intake section for adjusting the 2g BISS at the bottom of the article.

Fix those leaks (don't know about the BOV either), retest, see how much it helped. If it's still leaking, keep looking for those leaks. You can divide and conquer by testing at the TB elbow instead of the compressor inlet. If it won't hold there, you know there are leaks after the TB elbow. If it holds, you know the leaks are before the TB elbow.

 

[knochgoon24]

Does your compressor have a tank, or are you using a compressor made for filling tires? You may be having a problem getting enough pressure because at 10psi, you're leaking as much as you're putting in. Try to use a compressor with a tank.

Pressurize the tank to full pressure.
Set the regulator to 20psi.
Connect the tank to your tester.
Open the valve.

Hopefully, using this method, you can get enough air into your pipes fast enough to hear the leak.