When I do a cold start on the car, and the idle finally drops to its normal 850 RPM I sit just above 18 vacuum on my boost guage. Sometimes it even hangs out at 19 or 20.



After driving the car for a while, my vacuum drops to 17 or even 16. Rarely I saw 15, but I just added some 6 guage grounding straps and I think that helped a bit (I was having some funky idle issues).



I know it didn't used to drop vacuum like this. It only started after I replaced my turbo coolant lines, which is around the time my idle started going funny.



Is this somewhat normal? If not, what could be causing this? I know my air filter is really ******* dirty. Would that lower the vacuum?



Please help guys, I'm obsessed with my vacuum numbers because of this https://www.nopistons.com/forums/pub...DIR#>/wink.png

This may be related. I've been having some electrical problems as of late. When I put a large load on the system the idle fluctuates quite heavily when the engine bay is cold (does not matter if the engine is up to temp). I've been told vacuum will fluctuate on electrical load. Bad alternator maybe? I'd check my voltage but my multimeter broke.