WHY CAN'T I HOLD 15 PSI?!? Another dissatisfied, jaded KA-T owner.

[MarkEmark]

UPDATE:

I went ahead and connected the wastegate diaphragm to a boost signal from the intake manifold. I also routed the IACV line into the cold pipe (had a guy weld an aluminum fitting in there). And the result?

It's just as bad as it was before. Not even a miniscule improvement from before. Nothing. Bounces from 10 psi right back to 6 in a matter of 500 rpms.

Oh, and I developed a nice, substantial oil leak at the oil supply line to the turbo, and I have no idea why. This is great. I'm going to drive this ****king car off a cliff.

Where to go from here? I guess pressure test the whole system...I was really hoping that plumbing the IACV into the cold pipe would magically cure the boost problem, but unfortunately, it didn't, at all. There's got to be some major leak somewhere, and I guarantee you that when I find it, in accordance with Murphy's laws, it will be near IMPOSSIBLE to access/fix.

[Import_Ant]

did you eliminate your EGR? if so you could be having a large leak on the end of the intake plenum there if not sealed properly. also you could be having a leak from the actuator for your butterflies in your lower intake plenum. I know those are 2 places I had some trouble eliminating leaks. (I still have the leak in my actuator, it's not big enough to really give me much trouble)

It's no big deal setting up a boost leak tester and you'll be glad you did (even if it doesnt fix this particular problem). good luck fixing/finding the leaks!

[hysteria]

when i decided to turbo my car i removed the intake manifold, redid all of the vacuum lines and eliminated a number of things, ultimately making it something i could actually work on on the car if i needed to. my aicv was malfunctioning so i blocked it off, as well as removing egr and blocking off that bit with some sheet metal, silicon and some bolts. any problems here could of course cause boost problems but i really doubt that you would get the problems you are having. your problem sounds like something else because any mildly substantial leak in the manifold would cause irratic idle/dying etc... boost leak in the charge pipes is all i can come up with as i said before.

[fiznat]

Mark,

Have you tried to verify the accuracy of your boost gauge? Are you using an electrical or mechanical gauge?

I found that if the gauge power (not light power) voltage varies even the slightest bit, you can get HUGE accuracy problems. This is especially problematic if you are losing voltage during crank for startup. Where did you wire your gauges to?

I'm still convinced you have a boost leak though. Maybe you have something that isnt just a hole, but more of a lose coupler that slides up to release pressure only AT 12ish psi? This way, it wouldnt be evident at lower pressures, but only effects you once you have started boosting more pressure. Seems to reflect what you're describing...

[WDRacing]

I'm betting my money on a bad IC pipe coupler...look for a cracked one. Sounds just like my Skyline 3 years ago. Couldn't even see the crack unless I pulled the coupling off.

[MarkEmark]

did you eliminate your EGR? if so you could be having a large leak on the end of the intake plenum there if not sealed properly. also you could be having a leak from the actuator for your butterflies in your lower intake plenum. I know those are 2 places I had some trouble eliminating leaks. (I still have the leak in my actuator, it's not big enough to really give me much trouble)

It's no big deal setting up a boost leak tester and you'll be glad you did (even if it doesnt fix this particular problem). good luck fixing/finding the leaks!

No, I haven't eliminated the EGR. But when the engine was out, I had the EGR disconnected and I re-attached it using a brand new OEM gasket and torqued it down to FSM specs.

As I said, the tube coming from the EGR that used to plumb into the stock exhaust manifold has a long, flexible exhaust tubing welded to it and runs all the way down the downpipe and toward the mid section of the exhaust where it plugs into the cat for emissions purposes. Since the cat is not there right now, this tube is blocked off....BUT, there is a substantial crack in this EGR tube that just developed recently...but again, it has developed RECENTLY, and I've had my boost problem for a long time...It'll be fixed soon though. Could a hole in this EGR tube cause such a substantial boost drop?

Fiznat: it's a mechanical gauge, so that rules out the voltage causing accuracy problems. Not to mention, if just the gauge were inaccurate, I wouldn't be FEELING the HUGE loss of power across the rev-range. My butt doesn't lie.

Once I get ahold of a portable air compressor I'll test everything, but I don't see how my silicone intercooler couplers could have failed...they're literally twice as thick as the turbohoses.com couplers.

As I said before, the vacuum gauge is rock solid at idle and decellerating 99% of the time. BUT, ever since replacing the JWT ECU with a new one, and upgrading to a cobra MAFS and a top-feed fuel rail/MSD injectors, it has stalled a LOT more frequently than it ever did, only when I come to a stop....and the vacuum gauge jumps between 10 and 22 right before the engine dies. What about the seal between the fuel injectors and the intake manifold? What if pressure is leaking through those o-rings and rubber grommets?

I need to pressure test the whole thing to be certain. Hopefully I can do that tomorrow.

[SSS]

Where is the maf located in the piping? Before the turbo or on the cold side before the tb?

[MarkEmark]

Where is the maf located in the piping? Before the turbo or on the cold side before the tb?

Before the turbo

[MarkEmark]

So I got a 12 volt portable air compressor (Home Depot and Sears didn't have a 120 volt one, like I wanted), and I can't even get the system to build pressure...granted, the air compressor is terrible and cannot blow any harder than I can...

BUT, nonetheless, I hear a pretty major leak coming from what sounds like the actual turbo...not the hot pipe, not the cold pipe, but the turbo....I have the air compressor hooked up to the wastegate line on the turbo compressor right now, and I have the turbo inlet securely blocked off, and it makes this hissing sound coming from the center section of the turbo....Would it do this if the turbo seals were blown? Do blown turbo seals cause the type of boost drop off I was describing?

Also, when I had the cold pipe connected to the TB, i could hear a hissing sound coming from right around the TB area, but the TB is perfectly tight and every hose there is connected. When I blocked off the cold pipe, I didn't hear any hissing, and I haven't heard any hissing on any of my charge pipes/intercooler...

But I really need to get an air compressor that can dish out enough pressure to pressurize the system to like 15 psi and long enough so I can actually find what the hell is leaking.

Damn Home Depot, and damn Sears.

[Import_Ant]

if you want to get gangster, do what I did.

I had some intercooler piping laying around (if you need to get some O'Reiley's sells it as radiator piping. they sell 1 foot lengths in about any diameter you could want for about 20$~). you want some that's the same diameter as your intake pipe on your turbo. I went to home Depot and found a PVC endcap that fit PERFECTLY in the pipe. I got two clamps, tightened one around the end cap as tight as I could get then the other goes around the compressor. pick up a rubber valve stem seal and drill the end-cap (PVC IS EASY to drill) the package the valve stem seal comes in will tell you the size of drill bit to use. VOILA! now you've got a pipe that looks like an elongated boob. (eh... haha?)

drive your car to any gas station with an air compressor, pull over and remove your intake (wear some gloves for god's sake) attach your gangster pipe and hook up the air compressor.

yeah you won't be able to fix anything at the gas station and the turbo will be hot as hell but if you're strapped for cash and in a burn to find the leak that will work and you can still use your ghetto boost leak tester whenever you get a good air compressor.

I'm sure I'll get flamed for that but it's just my $.02

I'll post up a pic of mine for ****s n' giggles tomorrow or tonight.

[koukiKA240]

pressurize it to what you can, get you a bucket of super sudsy soapy water and where u think you hear a hiss comming from, dous the area with the soapy water, where there is a leak it will bubble, no matter the low pressure. So just do this for the areas you hear hissing, dont worry about a larger compressor.~Sam

[GEO]

Yo amrk you know whats its time for? Time to soap up your intercooler pipes.. soapy water each joint... and pressureize.. see if any bubbles occur.

[Jookmasta]

my vote is intake mani leak and boost leak. not running with the IACV hooked up could have messed up something down there under the mani. I dont know how ur car was running without that hooked up. And what WD said is probably what my guess was going to be. I seriously doubt that ur pipes would be leaking boost but i could bet that ur couplers would be first up on the chopping block. I suggest u take off each coupler and inspect them and also pray that ur leak isnt comin from under the intake mani.................good luck with it and keep us posted

[sanioll]

so definitely a boost leak. as rpm goes higher, turbo efficiency gets lower, it heats up, hole lets more air to pass thru.

just a thought.

[MarkEmark]

my vote is intake mani leak and boost leak. not running with the IACV hooked up could have messed up something down there under the mani. I dont know how ur car was running without that hooked up. And what WD said is probably what my guess was going to be. I seriously doubt that ur pipes would be leaking boost but i could bet that ur couplers would be first up on the chopping block. I suggest u take off each coupler and inspect them and also pray that ur leak isnt comin from under the intake mani.................good luck with it and keep us posted

The IACV WAS hooked up, it just wasn't plumbed to the cold pipe...and I highly doubt routing it to the turbo inlet caused any sort of damage...the IACV line never saw pressure the way it was designed to function anyway. Also, there was not a single noticeable difference in the way the engine ran/performed between when the IACV was plumbed to the turbo inlet versus when I had it plumbed to the cold pipe.

I guess it's time to soap up everything...I need to make a cap on my hot pipe witha valve so I can pressurize JUST the hot pipes, cold pipes, and the intercooler. But yeah, that air compressor is a POS

[WDRacing]

The hardest part here Mark is not giving up. I wanted to sell my 240 pretty bad last year. But I maintained and I'm glad I did. Between all of us we should be able to figure this damn thing out.

[hysteria]

i know this is unrelated to the leak because you hooked up the iacv correctly now, but if you hooked up your iacv to a non boosted part and boosted it up it can be damaged easily. i eliminated mine altogether because they are really fragile, and mine was toast anyway... all the inside of the iacv is is a plastic plate with a dinky little spring attached to it. they break VERY easily, and since they cost more than they are worth i just blocked mine off and said to hell with it. mine is not hooked up and the car ran fine as soon as i did this and put it all back together. before i did this my idle was crazy erratic because the iacv wouldn't shut.

yeah i vote for soapy water also... just like checking for a/c leaks... it works well.

[MarkEmark]

i know this is unrelated to the leak because you hooked up the iacv correctly now, but if you hooked up your iacv to a non boosted part and boosted it up it can be damaged easily. i eliminated mine altogether because they are really fragile, and mine was toast anyway... all the inside of the iacv is is a plastic plate with a dinky little spring attached to it. they break VERY easily, and since they cost more than they are worth i just blocked mine off and said to hell with it. mine is not hooked up and the car ran fine as soon as i did this and put it all back together. before i did this my idle was crazy erratic because the iacv wouldn't shut.

yeah i vote for soapy water also... just like checking for a/c leaks... it works well.

How'd you go about blocking your IACV off? Just capping that barb with something?

[hysteria]

i just took the iacv off the manifold (which is rediculously easy once the manifold is off the engine...) and then i cut a piece of sheet metal and drilled holes in it to match it up to the bolt holes on the iacv. then i just put some silicon on it and bolted it back down. took about 15 minutes with all the drilling and cutting. i did the same thing for the egr valve, but instead of reattaching the egr on top of the sheet metal i just left it off. i left the plug for the iacv off and my spring in the iacv was broken (before i blocked it off i opened it up to see what was wrong with it) so i removed that and reassembled it before putting it back on. the car idles better than ever and has no problems because of the missing iacv. i have had tons of problems with idle, but i have had absolutely zero problems related to the iacv after i blocked it off.

[hysteria]

sorry if i sounded like i was contradicting myself by posting that other thread.

up until a week ago the car ran just about perfect for 7 months solid, which is when i first blocked off the iacv. the problems i am having now are intermittent, so i really doubt it's related to the iacv. sorry for the confusion.

[MarkEmark]

A bit of an update:

I pressurized the hot pipes/cold pipes/BOV and tubing/intercooler...

And it had 3 leaks that I could find. BUT, they were all small leaks. And the air compressor literally cannot move 1/2 the air that I can move blowing into the vacuum hose...so under bost with a turbocharger moving air pretty quickly I bet these leaks aren't the main contributor to my drop off.

One leak was where the bypass valve mounts to the hot pipe....I had an elbow soldered on there and it was leaking around the elbow.

Another leak was where I JUST paid money and drove 35 minutes away to have a guy weld an aluminum elbow to my aluminum cold pipe...and the third leak was around the alcohol injection nozzle, where I always expected it leaked.

So I JB-Welded the SH1T out of all these three areas and will try again tomorrow to see if there's any more leaks (it's hard to listen for new leaks when you already hear two leaks, one on each side of the car).

If there aren't any leaks, then I'll try and pressurize the whole system again and see where it's leaking (and I'm sure there's some leak in the IM).

[WDRacing]

JB WEld is the best thing ever...best of luck homey.

[C-Kwik]

Try testing something. I'm not sure where you had your wastegate signal before, but if you have a port at the compressor housing, hook your boost gauge into that. Make a run and make sure the boost coming out of the compressor is similar to that in the manifold at WOT. If it is, try removing the signal line for the wastegate and make a run. To keep from overboosting, go part throttle, being careful not to boost much until you get near the RPM the boost drop off occurs at. Make a few runs gradually increasing throttle at these RPM's to see if the pressure increases at all. This will rule out any wastegate issues.

Getting a pressure reading at the compressor outlet will rule out any boost leaks. This would limit the problem to the turbo itself or the exhaust end of business. From here, I'd check for exhaust leaks.

With the motor cold, visually inspect and perhaps feel around for soot around any of the joints and make sure there are no cranks. A small turbo will see a lot of backpressure, especially towards the upper RPM's where efficiency drops off. The problem may be occuring only at these high pressures. Fortunately, exhaust leaks are usually easy to see evidence of since they do tend to leave soot around the leak. Any of the joints could actually be lifting, or a gasket may be leaking at higher pressures.

[WDRacing]

Good point man, thats another reason I use the intake mani as the source for my wastegate and boost gauge. This will help eliminate any pressure reduction cause by the IC or leaks since the turbo will just work harder to compensate.

WD

[MarkEmark]

Try testing something. I'm not sure where you had your wastegate signal before, but if you have a port at the compressor housing, hook your boost gauge into that. Make a run and make sure the boost coming out of the compressor is similar to that in the manifold at WOT. If it is, try removing the signal line for the wastegate and make a run. To keep from overboosting, go part throttle, being careful not to boost much until you get near the RPM the boost drop off occurs at. Make a few runs gradually increasing throttle at these RPM's to see if the pressure increases at all. This will rule out any wastegate issues.

Getting a pressure reading at the compressor outlet will rule out any boost leaks. This would limit the problem to the turbo itself or the exhaust end of business. From here, I'd check for exhaust leaks.

With the motor cold, visually inspect and perhaps feel around for soot around any of the joints and make sure there are no cranks. A small turbo will see a lot of backpressure, especially towards the upper RPM's where efficiency drops off. The problem may be occuring only at these high pressures. Fortunately, exhaust leaks are usually easy to see evidence of since they do tend to leave soot around the leak. Any of the joints could actually be lifting, or a gasket may be leaking at higher pressures.

I used to have the wastegate signal coming from the compressor housing, but, at the suggestion of someone in this thread, I hooked it up to a T that comes off the intake manifold so it's getting its signal from there. My boost gauge and wastegate now get their pressure from the intake manifold, so I could hook up a gauge to the compressor housing (I happen to have a very accurate mechanical 20 psi gauge that will do the trick).

As I've said before, there's a leak in the EGR tube that used to plumb to the stock exhaust manifold....I'm not sure if this causes any of the boost problem, but I don't hear air leaking out of it when I pressurize everything. Also, I've had recurring problems with the gasket blowing out where the downpipe bolts to the turbo...so exhaust gases could be escaping from there. But again, would exhaust gases escaping from the turbine outlet (where my 3 bolt downpipe flange bolts to) cause a boost leak?

Also, I tested the pipes/intercooler again today after JB welding the crap out of all of them, and I couldn't hear any leaks. So I went ahead and attached my cold pipe back to the throttle body to pressurize the intake manifold, and I can't pressurize the thing to more than 3 psi, whereas I could pressurize the pipes/intercooler to 15+ psi.

I hear a pretty substantial leak coming from, as I guessed, the inaccessible back-side of the intake manifold. Unfortunately, it's nearly IMPOSSIBLE to get at anything back there wedged up against the firewall.

Anyone want to take a guess as to WHAT exactly is leaking back there?

Here's a picture of all that junk at the back of the intake manifold, including where there's a crack in the EGR tube:

[MarkEmark]

I think I may have found where it was leaking on the back side of the intake manifold...I have no idea what the thing is called, or what purpose it serves, or if i can run the engine without it...



I believe it is called the "EGR and canister control solenoid valve," that, or the EGRC-BPT valve...

Anyway, pressure was escaping from the actual disk-like thing (see picture)

So I disconnected a vacuum line going to it, and plugged it, and there was no more leak (well, there was, but it was leaking from the actual bolt I used to plug the line).

So here's my question....can I just leave this line plugged and say f*** it to all that EGR crap (until emissions testing, of course), and if so, what other lines should I leave disconnected/plugged?

[Import_Ant]

So here's my question....can I just leave this line plugged and say f*** it to all that EGR crap (until emissions testing, of course), and if so, what other lines should I leave disconnected/plugged?

I completely eliminated mine. on the SOHC there is the same 'disk'. I've completely removed it and have had zero problems since day 1. (car's been running perfect for 2 ½ months now)

I think you could fix it by running a vacuum line where I drew the yellow line then putting a rubber nipple on the line where I drew the yellow blob. Anyone else want to offer an opinion? I guess you could also go buy a nylon 'T' fitting and connect all 3 of the lines. it looks like the vacuum/ID is coming from the upper left line though.

[MarkEmark]

I went ahead and connected that line i had plugged into the EGR valve like you said.

Apparently there's also ANOTHER leak within the EGR valve itself, in additon to the EGRC-BPT valve, although it's not nearly as big as the one in the EGRC-BPT valve. I don't know if it's stuck open, or closed, or what, but it's been disconnected for a pretty long time now; I wouldn't be surprised if it didn't function the way it's supposed to.

The only good thing is that this leak is pretty miniscule...With the whole system charged to 6 psi, when I shut the air compressor off it takes a good 20-25 seconds to lose all its pressure and go back to 0 psi, so I have a feeling that a turbocharger flowing like ~35 lbs/min (422 cfm), this leak will be negligible.

The only way to tell is to take the car out and see how it runs, now that FOUR of the FIVE leaks have been remedied.

Replacing the whole EGR valve seems out of the question at this point; it'd be impossible to do without removing the intake manifold and/or engine, and I really don't feel like doing that again. If I could get at it, I'd coat the whole outside of it with JB-weld, because it seems to be leaking below the disk.

I'll keep you guys updated. At least now I know WHERE the boost leak is coming from.

[fiznat]

If this doesnt work Mark, just suck it up and pull the entire intake manifold off. You can either go through it and delete all the emissions stuff like I detailed in that FAQ, or if you want I have a complete S14 intake manifold that you can use (which you can assume wont leak since I never took it apart). Vaccum/boost leaks do crazy things man, at least you're finding them-- you're getting closer and closer!

[MarkEmark]

Well I re-connected everything, went and started it up, and the idle jumped to 3000 rpm and kept climbing so I shut it off. Then I made sure the throttle cable wasn't snagged on anything and that the throttle plate opened and closed freely...then I removed the vacuum line going to the EGR valve and plugged the vacuum line, started it up, didi the same thing. Then I removed that larger hose from the egr valve, started it up, did the same thing.

I have no idea why it's doing this, but honestly, I give up. All I wanted to do was take it out for a ride and see if fixing 4/5 boost leaks did anything, even though I'm pretty positive, with the luck i've had, it'd run just as poorly as before. I spent all damn day sweating my balls off in my garage working on it, testing things, diagnosing and fixing crap, and now I can't even drive it.

Now, for those who know what they're talking about, would removing the EGRC-BPT valve altogether (which I did) cause the idle to do this?????

I've NEVER had an idling problem.