Boeing 717

Hey guys replaced diverter valve today, problem NOT solved. I did notice that when im really in the boost after i let off throttle to shift gears... the rpms's actually stay in one spot for a second or so before coming back down. Now im guessing that the valve is not getting vacuum. How can i test that. Also could it be that bronze circular peace that Bogey was talking about???

Gandara

Whoa this is wierd. Now I'm getting scared. I think I'm going to buy one of these.

Boeing 717

Buy one of what??

Staffan

Hmm, I remeber having this problem a few years ago, can't remember what it was.
Your engine is obv getting to much air at throttle lift, the re-circ valve should have nothing to do with it I think.
You only get this at throttle lift when you drive (under load)?

Thinking as I'm writing, could it be the AAV going bad?
I think that was my problem, it got worse and after a while my idle starting to get high since the AAV valve didn't close properly.

My theory is like this.
When you lift the throttle you have pressure in the intercooler.
The air want's to go somewhere and the re-circ valve will not open immediatly and due to a problem with the AAV some air will pass the slide valve by-passing the throttle house making the engine lean thus temporarly increasing idle speed.

Does it make sense?
If it does you could try by blocking the hose going to the AAV (right side of the intercooler).
If it cures the problem you know it's related to a AAV not completly blocking the air.

I run without AAV today after it stopped to work twice, I plugged the hose to the AAV by putting a piece of "rubber-like" material (circular, twice the diameter and about 1-2mm thick) at the intercooler connection and then pushing the hose back over it (hope it makes sense).

Edit:
They reason I'm pretty sure it's not the re-circ valve is that it doesn't by-pass air to the engine, it has to be something that is connected "down stream" the throttle valve and the only thing I can think of at the moment is the AAV connection (engine side).

Boeing 717

Thanks Staffan problem solved by removing vacuum limiter valve.

gr1275

Just so I learn something from Jerry's experience, what is a vacuum limiter valve and where is it?

Boeing 717

Its that round brass looking disk under the intercooler to the left.

JBL930

Commonly called a decel valve

Metal Guru

Yeah, the thing I told you to disconnect weeks ago.....
http://forums.pelicanparts.com/showthread.php?t=455899

Staffan

Ok great, I should have thought of that since it by-passes the throttle valve as well. Thought I was being really clever

Edit:
Read your thread at Pelicanparts.
I don't see running w/o it would be a problem at smog inspection from a measuring perspective, but I would run with it un-capped anyway to avoid potential questions from a visual inspection of the engine bay.

Running without it will seriously decrease the life span of the cat since your engine will be running very rich at throttle lift, but I'm sure you are aware of that.

Metal Guru

Fortunately I don't have a cat
But yes I agree with you on that. Both turbo and n/a cars need a controlled closing of the butterfly to avoid that puff of rich exhaust that occurs when the throttle closes suddenly. N/a cars use a dash pot that slows down the butterfly. Our turbo cars use the diaphragm valve that dumps high pressure air from the i/c into the engine behind the butterfly. Both are good at killing fast shifting and in our case, turbo "freewheel speed".
In my case I didn't disconnect the vacuum source from the diaphragm valve so that it would still operate and just dump air to the atmosphere. This works good for low boost as the blowoff valve won't open until high boost is achieved but the relatively high pressure air still is relieved from the intake between the butterfly and the compressor.
I really like this setup as it allows for fast shifting and lots of boost on tap ( boost now starts at 5 psi at initial acceleration instead of zero as the turbo hasn't lost so much speed) and overall makes the car feel a lot faster.

jayster

If you think the diaphragm in the diverter is leaking, dis-connect the vacuum line and blow through it. If you can blow through the hose, the diaphragm is leaking and it should be replaced. If the other side were leaking you could be losing boost pressure, and should be replaced. Actually, at your vehicles age, you should replace it , as my daughter would say, "just because.". As far as the decel valve goes, it could cause a delay in return to idle for a couple of reasons. Either of which would be grounds for "delete" mode. Simply remove it and cap the openings left behind. That would cure your idle problem. Also, check the "O" ring under your inter-cooler ( between I/C and throttle body). I have seen them blow out causing issues.
hope this helps...
Jayster

Metal Guru

Jay, if the o-ring was rolled out or shot, it would manifest itself with an acceleration issue and possible an idle issue.
Here's my solution foe the decel valve:

Ag02M5

Why not just remove it completely?

Metal Guru

Read my earlier post.