On idle at lights etc my boost gauge sits on -13 inHG @ 1000rpm or whatever it is. sometimes even worse like -5 and rough as idle struggling and revs hover between 200 and 500 rpm.
but when I drive along and take my foot of the accelerator it goes down to -20 like it should.... i think that is about right
It is a factory turbo with mx7 gearbox. rebuilt with liq. forged pistons, clive cams mild grind. 3 inch turbo back exhuast, fmic, stock ecu... etc.
can someone tell me whats going on???
you prob have a vacuum leak somewhere. check all hoses off the manifold, fmic etc. with an aftermarket cam dont expect to have same vacuum reading as a stocker.
but still 13 isnt good, id expect between 15-20 on idle. sounds like a faulty iac valve, and a lose vac hose, check for hissing in the engine bay, good way to find them is buy some start ya bastad and sray it around, and when it gets sucked in the air leak the RPM will increase significantly .
i gave never had anything better than -13 on idle, no matter what i did to the clamps and hoses. this is/was on both my calais' so if you find a solution, post it up
Some original photos have not been recovered yet.
I am glad to see someone reference vacuum properly! (in InHG, not PSI). However it should be just 13 InHG (not -13 InHG just to be pedantic )
A Larger custom cam will reduce the vacuum on idle. I had a N/A with a very large lumpy cam with quite a bit of overlap. It used to idle at about 10 to 12 InHG. Thing sounded like a V8 on idle.
Anything less than 10 InHG will make the engine strugle to idle at all.
A "Mild" turbo cam should be a bit higher than that - Standard Cam will idle at 22 InHG.
Some original photos have not been recovered yet.
well tried the trick with start ya ******* and could not find any leaks. I seem to be missing a lot of hoses in my engine bay tho. and cant be the rings coz the motor is only 1000km's old
