i don't think we are talking about the same thing here. to do a boost leak test, you must have the intake valves closed or else your going to get air passing out the exhaust through the open valves.

with the intake valves closed, it doesn't matter if the throttle plate is open or closed, the system (including intake manifold) will pressurize provided there are no leaks.

with the throttle body closed, air will leak past it into the intake manifold through the idle bypass valve. if you have a throttle body that is completely sealed when the plate is closed, you have a car that will not idle unless you give it throttle.

if you are filling the intake track with air quickly i.e. with a compressor, the air can only leak through the idle bypass so fast, so you will get pressure on one side of the plate and not nearly as much on the other, but given some time, the pressures will equalize provided the valves are closed.

if you are doing your boost leak test and only pressurizing everything prethrottle body (which you really can't do without plugging the idle valve) you are missing out on a bunch of potential leak areas such as injector o-rings (i had a leaky one), intake manifold gasket, vacuum lines, and other things attached to the IM.

 

I agree. That is why I am testing with everything installed on the car as it would be for running condition. With just the airbox and air tube removed.

Here is a drawing from Tial on their wastegate installation...


To me it looks like everything should be fine. They have the "other" side of the boost soloniod and the top port of the WG connected with a "VENT" in the line for fresh air.

 

I know exactly what your talking about with the idle bypass valve. But I don't believe it stops you from filling the intake manifold & combustion chambers with pressurized air. Think about how small that tire valve you are using to pressurize the intake track is then look at the size of the idle bypass valve... its more the double the size of the tire valve. Air will have no problem getting threw.

I must have pressure tested my car over 100 times in the 70k miles & 2 years I've owned it, not to mention other turbo cars in the past and currently. Never once have I had to touch the throttle body in order to find a leak

 

thats what i'm saying... from reading your post i was under the impression you were pressurizing up to the throttle body (no further), and thus your intake manifold was not seeing any pressure.

i was saying, air will go past the throttle body plate through the idle bypass, and thus fill the intake manifold.

you are correct that you do not need to touch the throttle body, because air is going to get on both sides of it through the idle bypass.

i'm saying air IS going to get past that plate. thus you MUST have the valves sealed or else you will get no pressure.

 

OK, I drove it.... first time driving the stage 2 first time in an EVO with a turbo upgrade, and it was very un-tunned.


WOW

Spooled up much much faster than I thought it would. Boost came on fast and held fine. I will try a boost test tomorrow. Right now the engine is too hot!!!!



[pats self on back] Stage 2 install (Turbo, Injectors,...), timing belt adjust, balance shaft alignment, alternator swap, and rod bolt upgrade...DONE! I had one small oil leak right above the exh manifold on the oil supply line for the turbo. Tightened it and 100%.

I'll let you know if the boost leak test works now that the engine has coolant and oil in it.




Thanks to resonance and STIwalker for helping with the wrenching.

 

Wow that is good to hear! I was starting to get worried that you wouldn't make the Houston Dyno day. I don't know if you talked to Resonance over the last couple of days, but he ordered the lower intercooler pipe but is now having boost spikes after the new BOV was installed. Besides the car not really being tuned, the car seems to run ok and you have everything installed for this weekend?

 

I wasn't worried at all. I had everything under control. Resonance will have his Lower IC pipe today installed tonight and be at my house/shop tomorrow to boost leak test it. I will have my bumper on and EVERYTHING buttoned up tonight. I drove my car up and down the street and it feels like everything is working great. I need to do a boost leak test, compression test, and the whole pre-dyno check list tonight. Then go put some slow miles on the engine to burn everything in.

Everything always works out!

 

So how's the beast doing? Were you finally able to perform a boost test?

I'll maybe see ya tonight when Res comes in, but I haven't heard if he got the lower IC pipe installed... but I am sure he did considering he IM'ed me at almost 1 AM last night

 

No, I didn't get to do the boost test last night. I put a new map in and drove it around to check my AFRs. Tonight is boost test night.

 

Cajun,
Did you do a pressure test on your EVO after you finished testing Resonance's car?

 

OK, tried to do a 30 minute boost leak test before having to get on the road to the dyno...

After I drove it (held 30 psi on street) it would hold 6-10 lbs before my bad leak tester coupler leaked. So, I just pulled it off and went to the dyno. My boost curve is FLAT --------. So I would say everything is holding well. Now, that was after I removed that screwed up Greddy Type s BOV that blew up on the dyno and replaced it with a Forge RS BOV.



Forge RS full soft >>>> Greddy Type S (with both springs full tight)


My Greddy seized on the dyno... Thanks to Resonance, I was able to finish the tune. We pulled his Forge and put it in my car. Then I got super lucky and Jorge had a Forge BOV at his house and I went with him to get it so I could be back running 100%.

I will boost leak test everything again this week up to 35 PSI. I run 30 PSI on meth.

 

True, but the Forge doesn't have the great purple color that the Greddy has.

Let me know if you need a hand with the boost test.