Does anyone have a boost gauge installed to compare readings to mine? I installed an Autometer 0-20 psi mechanical gauge on the weekend (used the BSH boost tap). Anyway I noticed my idle is not very even - the vacuum pulses between about 18 to 20 in.Hg every half second. Sometimes it idles steady though. Does that signify a vacuum leak or is that normal? Under full throttle it peaks around 14 psi.
At idle (when warm) the engine ocillates a few revs about once a second or so. It's small, 50-75 rpm, not so much as it will show clearly on the tach (because it is electronically smoothed) but if you listen to your exhaust you will hear it. That flux can easily account for the 2-inches of mercury you are seeing move in your boost gauge which has no e-nanny smoothing it out. When it's cold it will tend to be steady. 18-20 in-Hg at idle when the car is warm is exactly where it should be. 14 psi is about right for max "overboost". Sounds like you are running well.
ah thanks. Yeah it doesn't register on the tach, but I can hear it. It seems to be more pronounced now that I can see it on the gauge - probably psychological.:crazy:
I have a mechanical Marshall boost gage, with a BSH dual boost tap, in my MINI, it is steady at idle. Dave
it's a manual. It turns out I have a leak where I connected the boost gauge line to my BSH dual boost tap. It got worse and I started loosing boost pressure as well - wouldn't go over 2 psi. I bypassed the gauge and was back to full turbo power. Now I put some teflon tape on the threads where the gauge line screws into the BSH tap. It was OK for awhile, but returned at an autox event on Sunday. I think I will remove the BSH tap and start over. Wish I had gotten the electronic gauge instead:mad2:
^^^I used the "Push to Connect" tube fittings with my BSH tap..... They come with a thread sealant already on the threads. The fitting has a built in gasket that seals onto the tubing. There is even a bulkhead fitting that allows you to pass the tubing through the firewall. You press the black ring and the tubing pulls away from the fitting. Easy Squeezy..... McMaster-Carr