Crackership

Ok... so I've been trying to track down some vacuum leaks, so I've pressurized the system and have been listening for hisses and squirting things with soapy water.. I think I've found most of them, but there seems to still be a leak somewhere behind the head.. I can hear it, but I can't find it. What makes it even weirder is that the fuel vapor purge diaphragm buzzes when the system is pressurized... That confuses me. Any ideas?

TIA

tjbreen

My vapor purge diaphram was completely blown when tested. I think many are. I replaced the piece but idle vacuum is still the same. If your diaphram was whole, would it vibrate under pressure?

Scott H

Take the FVP diaphragm assembly out of the car and hook a vacuum tester to the nipple and see if it holds vacuum. If you don't have a vacuum tester you can use your mouth... though with a fuel vapor purge that is suspect to be leaking may not be the best idea.

A Mity-Vac is invaluable with these cars. Pick up the cheapy harbor freght version and use it only for testing if vacuum holds, don't bother using it as a brake bleeding assistant, it is crap for that.

Crackership

I'm sure many of the diaphragms are completely blown, mine may well be also... as for the question in bold, I have no idea..

I have a Mity-Vac... although, it's never occurred to me to use it to test for vacuum leaks... doh! I've only used it for bleeding brakes (which it does quite well)

I think I'm just gonna delete the vapor purge system... it'll get rid of some spaghetti under the hood and eliminate a few vacuum lines.

Scott H

That's the way to go if you don't have to get emissions tested.

Crackership

I think I've got it fixed... I pulled the purge system out of the car (no emissions issues here) and pressurized the system again... The only leaks I can find/hear after that are a minor one at the dipstick (the o-ring on the actual dipstick, not the one at the pan) and another very minor one at the oil cap... both are easily replaceable, and shouldn't see much vacuum from the engine (right?)

Getting rid of that vent crap really cleaned up the engine bay! I love it!

alxdgr8

Only a few more months and I won't have to do emissions on my 87! So I can finally transfer the plates from Indiana Now if I could avoid doing them on my Audi that would be nice, but I think I can get it to pass. And I put the cat in with clamps so it'll be easy to swap out after emissions.

Crackership

Don't they just read the OBD2 on the Audi? That's all they do on my beemer... It's still a challenge to make it pass though, stupid poorly designed secondary air injection (cat pre-warmer) system... always breaking and making the car fail emissions! It's not impossible to fix, but it may as well be... I think BMW quotes something like 60ish hours to repair it ($$$$$$$!!) And it does nothing but make the cats work a little better on cold starts

I just clear the codes and then drive it a bit, let it sit overnight and then go pass.

alxdgr8

95, so it's the last year for OBD1, which is a good thing since I don't have the factory ECU. It's just a sniffer test since it's AWD too so they can't put it on the dyno. Just do idle and 2500rpm emissions.

bw993

Can you show pictures of how you bypassed/removed the purge valve?

Crackership

I don't have any pics of the filter I installed, but it was just a $4 in-line fuel filter form Autozone... if you trace the evap line back to the tank, there's a junction between the plastic line and the braided fabric-stuff line... I just pulled the plastic line out, and stuffed the filter in the braided line with a hose clamp. Then, I pulled both vacuum lines off of the thermo-switch thingy on the water neck at the back of the head and plugged the one that goes to the nipple on the underside of the throttle body. I also pulled the line that connects to the J-Pipe and capped the nipple. From there it was just fishing out all of the braided fabric stuff hose out of the engine bay and removing the diaphragm. Pretty easy really.

zerMATT951

I put a cap on the throttle body port - that's one less vacuum line under the intake too.

Scott H

I removed the entire fitting and JB Welded up the hole.

Crackership

I've planned to cap it, I just haven't had time to go get one. Plus, I'm not really sure where to find one... where did you get yours?

That's definitely an option, I just have an aversion to doing things I cannot undo.

Scott H

I had an extra throttle body sitting around because I had broken that nipple on my original TB and bought a replacement. When I ripped the purge system out I realize I could reuse my original TB. So now I have my rebuilt/modded original in place and a rebuilt fully functional TB in my closet in case I need it in the future.