amirpc

I was testing my car out @ 17psi after running it all night at lesser pressures no problem.

After running it for a while I switched to fifth gear and unexpectedly overboosted, and heard a weird sound which I can't describe but it did not sound like it came from the engine. After that, my car had no boost limiting, which I assume means the WG isn't opening.

The weird thing is now the idle is bumped up to around 2100 rpm.

Anyhow I got under there and inspected all of the vacuum lines between the WG, intake, and MBC - everything looks okay. Out of curiousity I disconnected the line from the intake, and I plugged the hole - the idle stayed very high. As I let more air into the hole, the idle would drop lower.

Does this sound like a vacuum leak, or more like an obstructed vacuum line?

Bri Bro

Look at the diverter (popoff) valve. The stock one tends to fail under high boost conditions.

bigdeano

Did you check the hoses going to the ISV, J-boot, Throttle body?

amirpc

Is this the blow off valve? It is definitely still there, vacuum line still in tact.

I checked the one to the throttle body. I checked the blow off valve, I plugged in a bunch of semi-loose ones under the intake manifold going to the fuel pressure regulators/fuel pressure dampers and then to the blow off valve.

I'm not sure what the ISV is - If this is the cycling valve, I deleted that.

I checked the lines going into the J-Boot, they seem okay.

When I deleted the cycling valve, I plugged the J-Boot with a bolt and tightened it down real tight. If this were leaking, could I see this behavior?

I also checked the throttle position sensor and throttle to make sure they weren't just messed up, they seem fine. I played with the idle screw some and couldn't get it to go below like 1800 rpm.

Van

I think he means check the function of it... make sure the diaphragm inside hasn't been torn to bits by the high boost pressure.

amirpc

Well it isn't stock, it is a new unit about 5k miles old. I'm not sure where its from but its new and shiny. I'll take a look at it in a bit, but would a messed up blow off valve raise the idle like this?

Van

Actually, now that I think about it, I think not. The air has already been "metered" by either an AFM or an MAF - but it hasn't gone through the throttle body yet.

It shouldn't matter if that air goes through or around the turbo charger.

I'd look for air getting into the manifold post-throttle body. Like the nipples for the idle control stabilizer, brake booster, vacuum lines, etc. (I once had a brake booster nipple come out of the manifold...)

Darwantae951

As far as boost, I'd double check all the lines to the wastegate. One may have popped off seeing as you just installed it.

amirpc

Well it WAS working fine, and then it just stopped working. I have double checked the lines, they are all in place and they all seem like they are on fine. There are a couple that were really hard to get on - so I'm wondering if they might be kind of popping leaks under high pressure without coming off of the nipple. They aren't on the nipple very far.

Darwantae951

If you're using the same vac hose that came with the MBC, thats the same stuff I'm using. I made sure that they were fully seated on the nipples. Mine haven't had any issues. If you need some extra vac hose, I have tons.

amirpc

Thanks, I've got plenty for now I just actually couldn't get the hose on the nipples that came with my Tial very far. The install for me was insanely difficult because of the 1-piece X-over was causing the wastegate to hit the torque tube. So I was trying to put those hoses on the nipple at the most ridiculous angle, I got it on as far as I could and then put some zip ties around it. I'm planning on taking the wastegate off again soon to fix some of the shoddy work around there.

amirpc

Yeah I've been looking pretty hard for leaks, I am thinking I might have to just pull the intake manifold again and run new lines, zip tie up all the existing lines, etc. I have huge hands, I just can't seem to do anything without pulling the manifold!

Darwantae951

Where are you located?

amirpc

Austin, TX

amirpc

Yeah I have checked everything I can check without pulling the manifold

I can't really get at the ISV, I can see it and the lines look like they are going into it just fine.

I took out the intercooler to intake manifold pipe and checked all those lines, triple checked the vacuum line to the throttle, checked everything I could really get at. Hooked it all back up.

Its weird when I start the car it idles at the correct RPM for a few seconds, and then climbs up to the higher RPM and stays there.

The thing I'm having a really hard time checking are the brake vacuum lines, because I don't really know what they look like (the brake components). I was trying to figure out which ones they are by following vacuum lines but I'm losing them under the manifold.