I have a 99 v70 awd it's a 2.4 with the lpt I have countless upgrades but ever since I've got it the brakes feel weak (to me it feels like no power brakes) I've recently discovered this could be due to low vacuum and according to my ipd boost gauge at idle the vacuum is only at 14 or 16 when it's supposed to be 18. Does anyone know what could possibly cause this and how to fix it?

 

where did you measure the vacuum and at what engine speed? Do the brakes feel weak at first start up but then build to normal once you start driving? Do you hear the vacuum pump kick on at idle / first start (unique buzz sound that may toggle on/off)? do you hear any hissing when you press and release the brake pedal (ie brake booster leaking). Any whistling from under the intake manifold? did you try the rubber glove test on the oil fill cap?

A few possible causes - if brakes are soft at start up, check the vacuum pump or its relay or switch, or if the problem is full time (or if you hear hissing when releasing the brakes), check the brake booster. If you think your vacuum pressure is low, you may need to check the PCV system (there's a diaphragm valve somewhere in there...) but I'd suspect 15 PSI vacuum at idle and 18 or so during acceleration sounds pretty normal (but suggest you research more on the diagnostics parameters ) If you had a leak of major size, I suspect you'd throw a code and get a check engine light (for something like O2 sensor out of range...) so it wouldn't hurt to pull codes and inspect for vacuum line issues.

 

Thanks for the reply! I will check those things out. I forgot to mention somewhat recently I got a trouble code for abs pump motor failure and I haven't got around to fixing it,do you think that is related and could possibly fix the issue?

 

yes, the ABS pump failing would impact your brake pedal feel as well. I had similar happen on my 850T. Went with a used part and its been good for 75K miles since then.

 

Thanks for your help bro I'll try to replace the abs pump and see if it helps.