Boost leak or blown turbo.

[boostjunkie]

Okie dokie.

So after my intercooler hose blew off I started getting less and less boost. Now I don't even get positive manifold pressure!!

Made sure the my bov (with the crushed end) wasn't the culprit, so I took it completely out of the system. Plugged the two holes. No change.

Checked the wastegate. It would fully close and while the engine was still cold (and on) I opened up the wastegate slightly. Yup, exhaust gas would start leaking through the wastegate. I don't think that's the problem.

I have a cracked inlet tube into the turbo, but since that's pre-turbo I don't think that would be the problem.

So now I've gotta figure out where the restriction is? Would a boost leak small enough that it doesn't affect vaccum driving operation let off all boost?

I'm going to take off the intercooler again, check all vaccum hose listed in vrg3's post, and see whether that's the problem. Gonna check the turbo to see if it's not blown as well (freeplay, spins freely, etc). Anything else to check?

If the turbo's blown, I may have to take it to Extreme Motorsports for an 18G upgrade

[vrg3]

I don't think any of the vacuum hoses are big enough to leak all the boost out.

Hmm... Maybe the IAC valve could do it though, if it's sticking open or leaky. Just a wild guess though.

You could have a boost leak that opens only under positive pressure, and so isn't noticeable off boost. Try the starting fluid trick... look for extremely subtle changes.

You hear the turbo spool up, right?

[boostjunkie]

The IAC valve is attached to the intake manifold, correct? Sticking horizontally out of the manifold, passenger side with a larger hose that comes out, and does a 90-degree bend . . . seems to go down into the block, under the TB?

The reason I ask is that I pulled off all of the intake components. Checked the compressor fan. spins freely and no free play. That checked out. Checked the intake tubing post turbo. No significant holes (that would let 15 psi out). But that hose I was talkin about seems very weathered.

PCV?

I dunno whether I hear the turbo spooling or not. In the garage, I get this "whistling noise" whenever I apply throttle. It's definitely not the WHOOSH I used to hear when the turbo would build boost.

Also, the car idles PERFECTLY and drives normally (as far as I can tell) when not under boost. No CE lights.

[vrg3]

The IAC hose is attached to the resonator box. If the valve is open on boost it seems to me that it could leak manifold air back to the compressor inlet.

The PCV hoses do go back into the block... You can look at the vacuum reference I wrote up; it includes a diagram of the PCV system. The only place it could leak boost would be the PCV valve. You could try replacing the PCV valve... Couldn't hurt for $2.48 at Advance Auto Parts.

Too bad you don't have an automatic that would allow you to load the engine while stationary.

I know you checked the wastegate, but it still is possible that it's opening too early. A way to test it would be a to use a little pressure pump and measure the amount of pressure it takes at the actuator to get it to open.

[boostjunkie]

How much force is required to move a spring with a tension to hold 1psi? I can BARELY move the wastegate. I'll try the test anyways.

So the pcv valve is the valve I was talking about that comes horizontally out of the manifold. Hmmm, I'll have to replace that.

The IAC. Where exactly is the valve? I see the auxillary purge valve . . . is that it?

[vrg3]

It does take a lot of force to push wastegates by hand in my experience.

The IAC valve is just underneath the PCV valve.

Here's a picture of Josh's manifold with the IAC valve attached:

http://www.main.experiencetherave.com:8 ... P_2466.JPG

[boostjunkie]

Hmmm, the outlet to the IAC is pretty darn big . . . similar in size to the bov. It could be the problem as well as the WG.

OUCH! Those IAC valves aren't cheap, huh?

Could explain why I used to get those idle switch codes a few months ago? Maybe?

[vrg3]

I don't think a faulty IAC valve can cause the idle switch code to be thrown, but anything's possible.

The IAC valve hose is actually the same size as the blowoff valve's: 19mm.

And, yeah, they're not cheap. And unfortunately the turbo and non-turbo valves are different. I think the primary difference between JECS-ECU non-turbo IAC valves and turbo IAC valves is just the angle of the inlet nipple, though, so it may be possible to modify a cheap used one, or even just use a different hose.

I have an IAC valve from a 92 in front of me and it looks like you could just attach an elbow to the nipple.

[boostjunkie]

Oh, you have one, do you?

Is there any way to check the valve?

[vrg3]

Hehe, yesh, I have one. It really does look like a 3/4" elbow soldered on would do the job, maybe with a little cutting beforehand.

The electrical test is to see if there are about 9 ohms between the middle terminal (which should be labeled "B") and each of the other two (which should be labeled "A" and "C"). Yours will probably pass that test though.

If you have the valve on the bench, you can test its action by putting 12 volts on terminal B and then grounding either A or C. One of them will open the valve and the other closes it (the normal position at room temperature is about halfway open). It should open and close quickly and smoothly.

Of course, it should hold its position (open, closed, or partly open) at all times.

If it's sticky I would try cleaning it out with carb cleaner. If it seems to be off a little, you can loosen the two screws on top and adjust the static position of the valve.

[rsstiboy]

I'm not going to waste my time with the 18G upgrade I'm gonna get a 20G and do it right the first time, for your 2.2ltr it would be a perfect match!!

[boostjunkie]

Went to Autozone yesterday, but they didn't have the pcv valve. I wanted to check the IAC valve, but didn't have the equipment to test it. I figured I'd try to plug the outlet from the valve to the resonator and the inlet to the resonator. The ecu took a while to acclimate itself to the change in airflow at idle, but I just wanted to check if that was what was leaking boost. Nope, car still car the same as it has been . . . boostless. The whole time I heard it whistling like there was air escaping somewhere.

Is that a good indication that the IAC isn't necessarily the problem for no boost?

[LegacyT]

If you have IAC valve problems try cleaning it with carb cleaner. Usually they get messed up with carbon and varnish buildup. Cleaning it helps alot. beats shovin out 400 bucks for a new one.

Mark,