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Installed Intercooler.. Breather or not??

97AutoXVette

97AutoXVette

New member
Just installed my "old school" INTENSE intercooler core. This particular model does not have provisions for normal PCV function. I already have a valve cover breather, so went and installed it last night.

For those of you who have ran an intercooler and used a breather, how much did you have to modify your MAF table to adjust for the vacuum leak and the lean conditions at idle/cruise? I was adjusting my MAF table quite a bit last night but still seeing very high long term fuel trims.

Any help/recommendations related to this are welcome. Thanks!

 


If the intercooler doesn't have a pcv function, it is blocking the pcv. In that case, there is no vacuum leak. If your maf is way off, you probably have a vacuum leak somewhere around the plate or between them.
 
I was wondering if that was the case, but I sealed everything up really carefully and used quite a bit of RTV/sealant when installing the intercooler core, and then the blower.. Not saying it isn't possible, but I just would be surprised I guess. maybe I can spray something around the plates to see if I see any air/bubbles leaking.

Would the valve cover breather by itself (as the only vacuum leak) need that much MAF tweaking to offset it???
 
if that core is one of the non passage equipped cores...then it has no PCV or fresh air pathways to the crankcase, at which point the VC breather isn't a vac leak. the issue arises since many cores have PCV passage provisions but lack the fresh (metered) air path
 
I've never tuned a car with just a breather. I am guessing you would probably see inconsistent results due to the nature of the pcv valve. But that should have nothing to do with your situation.

Spray starting fluid around the plate while the car is running and listen for changes in the idle.
 


the front hole is for the fresh air. but since you likely have a TB adaptor plate, it may not be plumbed at the fresh metered air passage to the TB flange.

gen5 guys can easily run a hose from post maf/pre tb to the OEM fresh air nipple....that gen3's don't have (but you can add)

btw please tell me you pressure tested the core? a lot of em cracked n developed leaks
 
nm I see yer still stock tb with some spacer...make sure the spacer has the fresh air passage/hole and you wont need a breather if that core has the front and rear PCV holes
 
Turbocharged400sbc said:
nm I see yer still stock tb with some spacer...make sure the spacer has the fresh air passage/hole and you wont need a breather if that core has the front and rear PCV holes
Click to expand...

yep, stock throttle body (ZZP ported Stage 2 though) and the spacer does have the passage for fresh air. Maybe I will pull the breather off this evening and try it out.

Can't say I pressure tested the core, but I did run water through it and it didn't leak (not at high pressures though).. Fingers crossed I guess?!?!?!

So that port on the top left side in the pic (close to the 90* coolant inlet elbow) serves as a proper supply location for clean air into the crank case??
 
You can pull fresh air from behind the MAFF and route it to the front valve cover. Then you'll have metered air supplying the PCV function.
I used a stock oil cap extended and drilled a hole with a 3/8" push connector, and tapped from behind my MAF sensor.

IMG_0023.JPG
 
Thanks for the pic. That is actually the exact plan I had next, if my breather was still causing issues. Going to put the oil cap back on and remove the breather first and re-tune to see if the crazy fuel trims subside.
 


what are you gonna do for the rear pcv?


btw: that is the same way i had my front pcv working, except i tapped my tb and ran it there.(2000)
 
I had the same thing mguzzo had except I used a shrader valve in the vacuum line. I ran the line to the evap port on the throttle body. only reason I did that on mine was because I had too much crank case pressure and oil was coming out the dipstick tube. it doesn't sound like that is what is happening to you, but it might help your situation with the non functioning pcv.
 
SgtMarshal said:
I had the same thing mguzzo had except I used a shrader valve in the vacuum line. I ran the line to the evap port on the throttle body. only reason I did that on mine was because I had too much crank case pressure and oil was coming out the dipstick tube. it doesn't sound like that is what is happening to you, but it might help your situation with the non functioning pcv.
Click to expand...

being you had one of ed's ic's and i own it now, and i had to clear the rtv out of the pcv holes in th ecore. maybe thats how you had crank case pressure.
 
Scottydoggs said:
being you had one of ed's ic's and i own it now, and i had to clear the rtv out of the pcv holes in the core. maybe that's how you had crank case pressure.
Click to expand...

I knew this, I just didn't want to fix it the right way. I eventually got it right and took the pcv thingy off.
 
JamesIvey24 said:
what are you gonna do for the rear pcv?
Click to expand...

Rear PCV will still function like stock for when crankcase pressure goes positive.

Was mainly concerned about when the crank case is seeing vacuum, making sure the port in the throttle body still has a clear path to provide clean air to the crank case (and if not, the breather route or the vacuum line from post MAF to valve cover oil fill location).
 


Just removed the breather and installed the stock oil filler cap. Reset fuel trims with HP-Tuners and fired the car up. Checked and the oil cap is not pulling strong vacuum, which should be a good sign and that the stock PCV setup is operating as intended...

my fuel trims are still maxed at +16.4 with a lean idle. I can't hear any vacuum leaks and I was careful when applying the RTV when sealing up the intercooler core. Any other ideas on what I could be missing??
 
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