running lean, low vac, bov not opening???

[boost69]

hey i have been trying to get to the bottom of this problem for a while, and cant seem to find it, my sometimes runs rough at idle and very lean, when its running normal i drive it and it starts the problem, my vac reads, about 14-15, my wideband will go to 18-19s and when i drive it , it will boost slowly and not blow off right it sounds like the bov isnt opening all the way, i have no boost leaks or vac leaks, i checked the compression thats 150 across the board, getting good spark in all cyls, and fuel pressure is reading about 40. the only thing i notice is when i unplug the ISC it doesnt change anything, its very weird and i need to fix asap since this is my daily driver i just replaced the plugs wires and lower injector seals

please help

 

[TurboJimbo]

I believe that it could be your ISC...though they are kinda expensive from the dealer...around $170

 

[boost69]

would the isc cause it to run crappy and very lean?

 

[TurboJimbo]

Yes it can...especially when at idle...when they start to go bad they don't manage the air the way they should and it starts to throw things off

I actually have noticed that lots of ISCs start to go bad if you have a 2g with many miles and if its the orginal ISC

 

[boost69]

im going to take it to my buddys shop to have him take a look at it

 

[precisionMS]

ISC sounds like the problem.

 

[boost69]

i put in an isc off of my buddys car and nothing changed

 

[newtodsm97gst]

i put in an isc off of my buddys car and nothing changed

dig from the gave... did you fix the problem? my car is doing the same thing, I replace ISC and still doing the same thing, replace the wideband sensor as well and nothing change.

 

[eclipsyco]

Boost leak test it!
If you have a big leak somewhere after the maf the isc will be maxed out trying to compensate the air exiting from somewhere else, that will cause the rough idle and and it will run lean as well! And viceversa too if you have air entering from somewhere else that doesn't go throw the maf.

 

[newtodsm97gst]

i did blt and I did not find any of it. would a bad wideband causing it?

 

[eclipsyco]

The only way I can think of a wideband would cause that is if you have in in the front O2 position and simulated throw some tuning software.
Boost/vacuum leaks can be found not only in the couplers but also after the throttle body like injectors seals, TB gaskets the BOV al the small old vacuum lines running behind your intake mani also the ISC if it missing the o-ring, did you check all that?