I did a lengthy search but didn't come up with anything that really described what I have going on.

First off, when the car is started, there is a fairly loud sound almost like a turbine. This sound will continue for a few minutes then shut off. A few minutes later, it will start again. There is clearly something switching it on and off almost like what you would get with the AC pump.

Secondly, on acceleration, the car will build boost and accelerate normally for a few seconds then there is a distinct drop in boost and a wooshing sound starts. If I back off the accelerator, the wooshing sound stops and I can feel the boost rise slightly. From what I've read, this may be a DV problem but I don't have much experience with those.

Do I have two separate issues or are they connected? I'm going to take an in depth look at all the hoses today but I was hoping I could get a good jumping off point before I waste too much time wandering aimlessly around the engine bay.

 

It could be your AC, is the snowflake showing (if you have a model before about 2000) or are you not in ECON mode (if you have a model after 2000)? You should make sure your AC compressor is off to rule that out. The next intermittent device you can check is the electric cooling fan at the radiator..

When you say turbine, do you mean a woosh, or a dentist drill or what?

I dont know an exact answer for the boost problem, but it wouldnt surprise me if the DV could cause that, it is a canister the size of really small fist with two larger vac lines running to it and one small one (the other side of the small hose is connected to the very top/front of the intake manifold)..

 

Replied in the quote

 

Found something!

Behind the bumper, in front of the passengers side tire is a blower motor. There is a 90 degree fitting coming out of it and it looks like it was connected to a hose that looks like wire loom.

The hose from the blower motor is disconnected. It's an easy fix but what does that blower motor do and what is the technical name for it?

 

someone correct me if im wrong because i havent had direct experience with it, but i believe thats your secondary air pump (SAP) and again, i could be wrong but im pretty sure its a part of the emissions system.

 

That noise you're hearing and the thing you found is your Secondary Air Injection pump. There should be two corrugated hoses coming out of it. One of them is the inlet for the pump and should be connected to the front of your airbox. The other is the outlet of the pump and should go up and connect to a hard line that's bolted to the compressor housing on your turbo. From there the metal hard line goes up over the turbo, along the valve cover and back to the combi-valve on the back of the cylinder head.

Living legend was correct, that whole mess is part of your emissions system. On cold starts the SAI pump pumps clean air back to that combi valve. There are passages in the head that allow the clean air to mix with exhaust gasses as they exit the motor. This creates an after-burn effect that serves to heat the catalytic converter up more rapidly.

It should be running when you describe, but if it's louder than a dull hum, it's too loud. Mine went bad so I ripped all that **** out

The other problem you described does sound like a DV issue and isn't connected to the SAI pump problem. The SAI pump is connected to the cylinder head and to the low-pressure side of the intake tract. Even if it was ripped out completely, it wouldn't cause a boost leak like you're describing. My suggestion would be to build yourself a boost leak tester and test your diverter valve.

 

^^ Great call, that should be what it is, especially because it is intermittent.. I always forget about that pump cause I have a 99.

 

Here's where I am at so far:

I fabbed up a hose for the SAP and it's running silently now.

I pulled the DV and tested it. With my thumb over the vacuum port, the diaphragm is holding tight. It snaps closed when I take my thumb off the port.

I guess my next step is to build a boost leak tester. I gave the hoses a thorough looking over but didn't see anything that looked suspicious.

I really hate problems like this. It's like chasing electrical gremlins.

 

Doing a visual inspection is a good start, but there's tons of little check valves and old *** rubber vac lines that can leak without looking suspect. The boost leak test will make the leak easier to find. I have a tester I can mail you if you promise not to steal it

 

I really appreciate the offer but it would probably cost more to mail it back and forth than it would just to build one. Plus, I know it's going to be one of those things that gets used multiple times.