PCV catch can = Slow downshifting?

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Shaman

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I installed a catch can on my car, and it doubled the length of hose between the IM and PCV valve. It also put some bends into the equation. Afterwards, I noticed that the transmission was hanging on a little longer than it used to. Seems to me that the vacuum has been affected, which could cause the transmission to do what it's doing.
Any thoughts?
 
That shouldn't have much to do with it. Maybe if there's a serious leak, but that can be fixed with tighter clamps.
 
A good spot to check for leaks is the plastic bowl to the aluminum body of the catch can [if you use a air line water separator type]. The 'O' ring gasket may not seal, or fall out, so use teflon tape on the bowlthreads. Also, some have leaky valves that empty the bowl. Some are not suitable at all, because they seal on pressure, and we need types that seal on vacuum as well.
 
It's the air seperator type. I need to size up my IC and TB pipe to find a replacement, so I will tighten up the clamps, and see what I can find out about it. It's one I bought from Walmart, Campbell Hausfield.
 
Isn't that what a pcv valve is? I have another PCv valve I can use. I will try the carb cleaner spray to check on the vac leaks this weekend.
 
Originally Posted By: Shaman
Isn't that what a pcv valve is?


Yes, but in my case I found the pcv valve leaked when under boost, so I got a new pcv valve and it leaked as well. Installed a check valve and no more boost leak.
 
A good start would be finding out if the trans runs on computers, TV cables, vacuum modulators, or a combo of the above.

Similarly we should find out if the car runs on a MAP (vacuum) sensor or mass-airflow.

Every PCV valve I've seen is completely dumb, no computer connection or involvement. It flows such a low % of air at moderate to heavy throttle I don't see how it can be involved, to a positive or negative, to any vacuum reading elsewhere in the system, if the catch can is somehow causing a restriction or leak. If you had a substantial leak, you'd have a higher idle.

Another good test would be to run the same length hose but without the catch can.
 
There is a cable connecting the throttle to the trans, and there is no MAS that I can see. Mechtech, what do you mean I need a different catch can?
 
Better check the performance sections of boosted cars like SR4t neons and such. They have good details.
The common type of air/water separator does not work in all conditions on a boosted car - only sometimes. Leave it stock or get the right aftermarket system.
 
Originally Posted By: TurboLuver
Originally Posted By: Shaman
Isn't that what a pcv valve is?


Yes, but in my case I found the pcv valve leaked when under boost, so I got a new pcv valve and it leaked as well. Installed a check valve and no more boost leak.


They're only designed to prevent a violent backfire from reaching the crankcase. Those that I've taken apart (not all that many- since you destroy them in the process) actually have like a spring figured in there in one manner or another that stops them from fully seating. I doubt you could fully reverse bias it without the expansion shock of a backfire.


If a vac leak is responsible for a delayed downshift, it would also reason that it would effect the upshift as well. If you've got normal shift points on the way up ..then I doubt that you have this problem with that as a source.
 
That's where I would start.
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