running lean

[titan1]

My car has been running lean lately so for kicks I put on a Boost Leak Detector and put 20lbs to it and sure enough air was pissing out the back of the plenum. The bolt in back, in front of the coil pack is gone. Must of rattled out. Question...Could air actually be sucking IN through the hole when under boost, leaning me out? Thanks

 

[chadly]

It would create a vacuum that would add to a lean condition. How lean is it? Scan master numbers? What do the plugs look like?

 

[titan1]

the plugs are fine just changed them the other day. Been chasing this problem for a few days now. Never had a problem untill this weekend...All of a sudden knock and O2 readings in the low 700's So I tryed this today and when I heard the leak I saw the bolt gone. My buddy swears that air will come out under boost, I told him I thought it would act like having a car window cracked going down the highway smoking a butt. The smoke gets sucked OUT of the car ( or into the plenum ) I hope I am right and plugging the hole will fix me

 

[chadly]

I hope it fixes it too. You may want to watch your fuel pressure under boost as well. Be sure it’s going up one pound/pound of boost.

 

[3.8L V-8 eater]

I just had a similiar problem with the plenum gasket blowing out the side of the plenum. My BLM's at the time where 130 and they went up to 142. Replaced the gasket and they went down to 124. So that tells me it had to be sucking air in order to go from a lean condition at idle to a slightly rich condition.

Do you have a scanmaster???

 

[ronbuick]

20lbs. boost, is that on pump gas??, what is your combo, at 20 lbs. hope you have race or alky for that 20lbs, more info please, boost creates a positive
pressure, just cruisin around you get a negative press. do you have a boost-vacuum gauge, or just boost gauge.

Ron

 

[titan1]

i have a 6176 turbo 63# injectors alky hotwired FP 23 row SLIC 3" downpipe 3" x haust TT alky chip Bolt on stuff. Stock Cam, heads. I have been running 20#-23# Never a problem. Then one day I'm getting knock and running lean. Plenty of FP. No Vacuum leaks. Un-metered Air is somehow getting in. Maf is reading 255 at WOT I'm hoping that Leak is it. I will know today.

 

[ronbuick]

what did you fine out??

Ron

 

[ronbuick]

what did you find out??

Ron

 

[titan1]

I'm still lean...Just now on the highway on the way to work O2s were 730 1.2 KR I've added fuel pressure, added fuel in the chip, got the ALKY buried. 1/2 -7 used to be fine. Startin to piss me off. Something happened. The car just doesn't all of a sudden run different. I even got KR pulling away from a stop sign. O2s read 830 Motor mounts maybe?

 

[djj624]

Did you check fuel pressure with a gauge making sure its rising with boost?
Im going through the same and found out im not pumping enough fuel.