Vacuum sources / tapping UIM
 

I have a CA car that needs to retain all smog equipment. Currently the extra nipple on the outer turbo side of the UIM is in use by an AEM methanol controller. I'd like to add a boost gauge, but I'm not sure where a good additional place to tap into boost/vacuum is. I've read that sharing the OE 4mm nipple isn't a good idea (although I'm skeptical of that).

Are there any extra unused nipples hanging around on the UIM I haven't noticed? (I will have it off over Christmas) Or any particularly good or bad places to tap the UIM to install a new one?

Use a brass T and share a vacuum source. Theres nothing wrong with it. In stock form, all the ports are being used. Sharing is the only option you have unless you install a vacuum block. In reality a vacuum block is just a huge TTTTTT fitting. So you're good

I was thinking most vacuum blocks have one or two large ports on them in addition to the smaller ones which might help mitigate any equalization delays. But yeah, that really just seems like splitting hairs, especially if it’s for human-readable instrumentation.

I just realized that, since I’m about to install a catch can and eliminate the UIM PCV, that 8mm port on the UIM could be a good place for a block source. But again, if teeing off the 4mm is not discouraged, I’ll just do that.

Yeah no problem running T's. ALWAYS use brass, never plastic.

The line diameter is pretty small, you won't see a noticeable difference in readings. I've done it before many times, you'll be fine.

Dale

Oops

great info to revive a 4 year old thread... it is never too late to put valuable information on the table !