My 1988 IROC T.P.I. is no longer stock, but heavily modified with a 383 BLOCK and 10:1 compression. With that being said do I now need to vent the crank case block from the valve covers into the open air or do I continue to do the original design and plumb it back into the intake on one side and cap it off on the other side. Reason being is a guy at a local speed shop told me that my engine needs to breath. But he knows more about carbs and such than fuel injection.

 

I would say it needs to breath also. Just get a breather and stick it in the valve cover.

 

I am having the same problem with 10.3 to 1 compression, but I am carbed.

I put a breather in each valvecover, but if I make a full throttle pass, it blows oil out of them. So you might end up with the same problem.

I have thougth about a evac system plumbed into the headers. I dont know how well this works on the street. They do make pumps, but that can run into some $$$$.

I am going to try and hook the PCV system back up, but it might not be enough.

 

Even a performance car need a PCV/breather system. If your sucking oil out of your valve covers you either need a better baffle in them or your rings are not sealing well. You can't seal the motor or it will blow your gaskets out.

 

I would say connect it up like it supposed to be, although either side should not be capped off. The passenger side should be connected to the throttle body connection in front of the throttle blades, thats were it pulls the fresh air in after it has metered by the MAF.

 

Battman's right. Put a pcv valve on one side (note:constant vacuum, not ported). Then put a nice looking breather/filter on the other valve cover. This is a must for not blowing out seals and will prevent slugging.

 

HMM,
WELL RIGHT NOW I JUST HAVE THE PCV ON THE DRIVERS SIDE AND A BREATHER ON THE PASSENGER. I WILL TRY AND REROUTE THE BREATHER ON THE PASSENGER SIDE TO THE THROTTLE BODY AND SEE HOW IT WORKS!
THANKS EVERYONE!!!!!!!!!!!!!

 

It doesn't matter witch side it's on.

 

I should of metioned that the line from the passenger side valve cover to the throttle body does not exist right now on my IROC. I blocked off the throttle body tube were the hose would go and just have a breather on the valve cover. Drivers side is hooked up right. PCV in valve cover to a hose that goes into the intake manifold.
By the way does this have any drivabilty problems such as my IROC will die while at idle which is at 750rpms. It will drop down to 500rpms then die. I have to watch it when Im driving cause when I pull up to a light is when this usually occurs!

 

That’s exactly whats causing your drivability problems; your PCV is sucking air that is unmetered by the MAF. The way its configured its just a big vacuum leak.

 

Batman;if what you say is true, you have made me very happy! And not say I don’t agree but could anyone else confirm what Batman has said. As I will work on this tonite!!!

 

If you have air going into the engine it needs to be seen by the Mass Air Flow Sensor. So if your breather tube is disconnected from the air snorkel the MAF cannot see that. I'm not sure how sensitive these are but, if not you can have driveability issues, MIL's ect. Unless the ECM calibration allows for a vacuum leak such as a pcv valve. Which is highly unlikely due to nature of the leak (large). It is definately worth trying.

 

just remember when you connect it up do not connect it to the port on the throttle body that has vacuum. I think its the smaller port that goes to the purge canister that has vacuum anyway.

 

Say how does the MAF read the in coming air that’s coming from a separate line into the throttle body (crank vent case)? When the MAF is attached and I know reads the actual in coming air from the outside.

 

Ok the PCV valve is connected to a vacuum port on the plenum, the pcv is connected to the valve cover of the engine which creates a vacuum in the crankcase. the other valve cover is is connected to the throttle body which is where air is pulled from the intake track after the MAF has metered it.

the way you had it connected the air pulled into the crankcase is coming from the engine compartment which has not been meterd by the MAF so the engine is getting more air the the ECM thinks its getting. make sense?

 

 

Yea I got it now!!
I originally had 2 breathers 1 on each valve cover. I then wanted to try several different things to see if any drivabilty problems would go away.
Thats when I wanted to see what would happen if I had a pcv on 1 valve cover to the plenum and a breather on the other with venting into the engine bay.
I tried tonite what you said Batman and it does seem better drivabilty but it still is a little rough when I try to hold about 35-45 mph just not as bad. But it still died on me when I came to a stop a couple times or tried too. So I guess its back to the drawing board!
Thanks again for your input...

 

Have you performed the minimum Idle Air Adjustment procedure?

 

I have done the IAC awhile ago. But not recently and for sure not tonite since I rerouted the crankcase venting. I'll give it a shot tomorrow.
thanks!!!

 

Don't use a pcv valve. That will reduce horse power by introducing hot air in your engine. Use a reflector that bolts over your rockers.

 

Iv'e never heard of a reflector. Is that the same as a breather that goes onto the valve cover? Example "Moroso 68781 - Oil Separator/Breather"

 

Maybe we can help you better if you post the the mods you have done, engine specs, has it been tuned, etc.

 

That would be great for any help or tips I could get to correct my problems.
The easist way is click on my garage and read my IROCS profile.

 

Have you tried to run it with the original MAF? When you say it runs rough at 35 to 40 mph, is the car bucking or does it seem more like a miss?

 

Yea it is bucking more or less. My oringinal MAF was stolen. But when I had the custom chip made he asked if I had no screens which I said yes.
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Also does the pcv kill hp. like what camaro1j said?

 

If you install a breather on the same valve cover that has a PCV valve in it, would there be any ill effects on the PCV? Could doing this allow the PCV to flutter and allow oil into the intake through the PCV line?

 

The PCV is not stealing any power from your car, The things that will cause it to buck is usually two things, a vaccum leak or to much spark advance in the tune. Maybe try running the original prom in the car and see if the bucking gets better or worse. I had the same bucking problem and eratic idle when i was running the 165 ecm in my car, It was a combination of both, a leaking intake gasket and two much spark advance in the tune.

 

Well im running the base/intial timing at 16º

 

yea mine would still buck no batter what my base timing was set at, there was two much spark advance in the chip.

 

I think I still have the oringinal chip, but it still has the Hypertech off road chip attached to it from one of my first mods.

 

Hey Batman,
was your chip a custom, or what?

 

yea, it was done by LSracingchips.com, It was good except when cruising around 1800-2400 rpm it would start bucking

 

Hey Batman,
I put in the stock chip back in the IROC and ran worse! It also had a hard time starting. As soon as I put the custom chip back in it started right up and was fine. I tried to tune it more by adj. the Granittilli mas sensor and bump up the throttle a little more. It did seem to help put after cruising around for awhile it once again died on me as I came up to a light and I wasn’t doing anything crazy either before, just cruising (it was good for about 1/2 hour to 45 minutes before this; as usually is the case). The idle went from 700-800rpms to 500 for a couple of seconds, then cause it seem it could not run that low it just died.

 

Adjust the IAC