368 LT5 Drinking oil

[icarus-54]

You need a baffle or something to keep the oil from being sucked into the pvc,ya want to get on the front end of the problem.

[A26B]

Originally Posted by icarus-54

You need a baffle or something to keep the oil from being sucked into the pvc,ya want to get on the front end of the problem.

This is not possible in the LT5 due to the engine design. Simply no place to add any baffles. Here's why.

The LT5 doesn't have a conventional style of PCV system. The majority of the crankcase vapor comes up through a large baffle with cover and 2 large hoses to an isolated chamber in the injector housings (all under the plenum).There are 2 small holes in the cyl head (or inj hsng if 1990 model) that vapor from the cylinder heads passes through, into the same isolated chamber. The pipes with grommets you see on the outside of the injector housings then connect to the PVC hose at the rear of the plenum.

Regarding the pipes from each cam cover to the air horn, in front of the throttle body; Those pipes are for filtered/fresh air purge of the crankcase.

• Under normal driving/high vacuum conditions, air flow is INTO the cam covers, through these pipes.
• Under WOT/low vacuum conditions, crankcase volume & pressure is greater than the PCV system can handle. Reason is simple, no engine vacuum, no flow through the PCV valves except for positive pressure flow from high to low pressure.

The same principal applies to the cam cover tubes, thus the reason for the cam cover "filters," whose purpose is actually mist extraction. WOT flow would then be from the cam cover to the engine air inlet at the air horn.

So, under WOT, low to no engine vacuum conditions, heavily laden oil vapor can reach the plenum by two different paths, PCV system and the cam cover filtered air purge tubes.

The amount of oil in the crankcase vapor depends on engine condition and will normally accumulate in the plenum through the PCV system, even under normal driving conditions. Not a perfect condition, but not a serious problem either. It is a condition that can be improved upon, but not entirely eliminated, with the installation of an oil catch can. WOT conditions can still result in oil through the air inlet. The more blow-by the more oil.

[Karl]

Check here

http://m.corvetteforum.com/c4-zr-1-d...ntrol-ecm.html

[icarus-54]

Got ya,BTW Jerry,thanks for the excellent explanation,really helps my understanding how these things work.

[ZZZZZR1]

Stock 1991 chip?

Do you need one? I can let you borrow it to use.

Want me to ship?

Cheers

David

[FU]

I'd be Frank U.
Wait a second........go back to the original post. Who built the engine ?
The Vette Dr's (Billy Kirchoffer) built the engine ?

Originally Posted by Bob G

call frank u he probably knows whats wrong !

Bob my brother, I miss you guys !

[Mitsumark]

David to the rescue..I would appreciate that immensely..I'm gonna PM you my addy.. 2 weeks tops and I'll have it back to you with shipping for both ways..I really don't think it's the tune but this will allow me to fully rule that out(hunting idle/rich condition)...

I'd be Frank U.
Wait a second........go back to the original post. Who built the engine ?
The Vette Dr's (Billy Kirchoffer) built the engine ?


Quote:
Originally Posted by Bob G
call frank u he probably knows whats wrong !
Bob my brother, I miss you guys !

Oh ok Frank..Yes Vette Docs built the motor.You work there?..Original chip had Kirchoffers name on it..


UPDATE on the oil burning.. I installed the Moroso oil separator inline today and the smoke totally stopped after a good 15 min romping..Upon installation I noticed a fair amount of oil in the PCV tract along with the Map hose and sensor..So don't know for certain but I'm thinking the oil that is making its way to the map is really altering the A/F mixtures being the MAP is being choked on with oil..Thus causing an overly rich condition,fouling of the plugs, and the hunting idle..I'm already happy as I don't have to see that embarrassing smoke cloud behind me when I accelerate..I'll update again soon..

[FU]

Lets start at the base.......
Do a compression test , preferably a leakdown compression test on the engine first.

When was the engine built ?
How many race miles have been logged on the engine since becoming a 368 ?

Are you checking the oil after the car has been sitting for at least an hour ?

VD 368.............

[ZZZZZR1]

Originally Posted by Mitsumark

David to the rescue..I would appreciate that immensely..I'm gonna PM you my addy.. 2 weeks tops and I'll have it back to you with shipping for both ways..I really don't think it's the tune but this will allow me to fully rule that out(hunting idle/rich condition)...




Oh ok Frank..Yes Vette Docs built the motor.You work there?..Original chip had Kirchoffers name on it..


UPDATE on the oil burning.. I installed the Moroso oil separator inline today and the smoke totally stopped after a good 15 min romping..Upon installation I noticed a fair amount of oil in the PCV tract along with the Map hose and sensor..So don't know for certain but I'm thinking the oil that is making its way to the map is really altering the A/F mixtures being the MAP is being choked on with oil..Thus causing an overly rich condition,fouling of the plugs, and the hunting idle..I'm already happy as I don't have to see that embarrassing smoke cloud behind me when I accelerate..I'll update again soon..

Take your time with it. No worries

Will ship it tomorrow



David

[emmvette]

One more thing to add to the list of potential sources for the issue: My car was running very rich on one side and after some serious trouble shooting, Marc H figured out it had a decent leak through one of the headers. He welded this up, then completed a tune and it was good to go. On my car, it was running very rich on the side with the leak and a little lean on the other side. I think you would need to be connected to the car's OBD system with a scan tool to read this.