Caution: Do NOT Route Your PCV Tube to the Front of the Air Bridge
09-15-2007, 12:07 PM
#1
Melting Slicks
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Location: Northville Michigan
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Caution: Do NOT Route Your PCV Tube to the Front of the Air Bridge
Gentlemen,
I would like to relate to you a problem I just had on my Z06:
~ Late last year I had a Supporting Tuner take my Z06 and clean up the tune.
~ As part of his work he found where another shop which had done work on my car had installed the wrong exhaust manifold gaskets between the cylinder heads and my L.G. Motorsports headers. The gaskets that were on the car were leaking, which would cause an incorrect air-fuel ration reading by the O2 sensors.
~ He also recommended that the PCV tube from the passenger-side valve cover that normally runs up to the throttle body be rerouted so that it connected the valve cover to the front of the air bridge just behind the MAF.
~ After a recent track day at Waterford Road Race Course, I noticed oil dripping out of the bottom of my VaraRam.
~ Last week I removed the air bridge and the upper portion of the VaraRam and found a significant amount of oil (8 to 10 ounces). This oil had fouled the MAF, the air filter element, and was running down the bottom of the VaraRam housing. The oil was coming from the PCV tube that had been routed to the front of the air bridge.
~ When the MAF becomes fouled, the PCM enriches the fuel mixture.
~ I used Brake Kleen to clean up the MAF, and the lower housing of the VaraRam, and installed a new air filter element.
~ I also rerouted the PCV tube back to the throttle body.
I had been baffled by a loss in fuel economy over this past summer. Instead of 26 to 28 mpg, I was only achieving 21 to 23 mpg. Since I cleaned the MAF, rerouted the PCV hose, and installed a new air filter element, my fuel economy is back to the 27 -28 mpg range.
Also, while I was working on the Z06 I installed a set of Smith Brothers 5/16 inch x 0.083 inch wall x .7250 inch long (this is the correct length for use with the Crane 1.7 or 1.8:1 aluminum roller rocker arms) oil restricting pushrods. For those of you who turn high rpms and/or participate in Autocross, Road Racing, or HPDE events, you should consider installing a set of these pushrods. They significantly reduce the amount of oil that gets pumped up into the valve covers. Instead, more oil is maintained in the pan where it can be used by the mains and rods.
Finally, I also installed a set of Champion Iridium spark plugs - part number 9405. I am very pleased with the new smoothness at idle, along with their part throttle and wide open throttle performance.
I would like to relate to you a problem I just had on my Z06:
~ Late last year I had a Supporting Tuner take my Z06 and clean up the tune.
~ As part of his work he found where another shop which had done work on my car had installed the wrong exhaust manifold gaskets between the cylinder heads and my L.G. Motorsports headers. The gaskets that were on the car were leaking, which would cause an incorrect air-fuel ration reading by the O2 sensors.
~ He also recommended that the PCV tube from the passenger-side valve cover that normally runs up to the throttle body be rerouted so that it connected the valve cover to the front of the air bridge just behind the MAF.
~ After a recent track day at Waterford Road Race Course, I noticed oil dripping out of the bottom of my VaraRam.
~ Last week I removed the air bridge and the upper portion of the VaraRam and found a significant amount of oil (8 to 10 ounces). This oil had fouled the MAF, the air filter element, and was running down the bottom of the VaraRam housing. The oil was coming from the PCV tube that had been routed to the front of the air bridge.
~ When the MAF becomes fouled, the PCM enriches the fuel mixture.
~ I used Brake Kleen to clean up the MAF, and the lower housing of the VaraRam, and installed a new air filter element.
~ I also rerouted the PCV tube back to the throttle body.
I had been baffled by a loss in fuel economy over this past summer. Instead of 26 to 28 mpg, I was only achieving 21 to 23 mpg. Since I cleaned the MAF, rerouted the PCV hose, and installed a new air filter element, my fuel economy is back to the 27 -28 mpg range.
Also, while I was working on the Z06 I installed a set of Smith Brothers 5/16 inch x 0.083 inch wall x .7250 inch long (this is the correct length for use with the Crane 1.7 or 1.8:1 aluminum roller rocker arms) oil restricting pushrods. For those of you who turn high rpms and/or participate in Autocross, Road Racing, or HPDE events, you should consider installing a set of these pushrods. They significantly reduce the amount of oil that gets pumped up into the valve covers. Instead, more oil is maintained in the pan where it can be used by the mains and rods.
Finally, I also installed a set of Champion Iridium spark plugs - part number 9405. I am very pleased with the new smoothness at idle, along with their part throttle and wide open throttle performance.
09-17-2007, 12:51 AM
#3
Drifting
There is a pressure differential between the front and back PCV loops to make it ventillate. Sounds like your ventillation direction was reversed. 
Sorry to hear that.
Even when hooked up correctly the oil spillage has been frequently reported. You still get similar oil spillage on high lateral accelleration. Then the oil loosens the glue on the hydrocarbon traps and the engine inhales them.
The solution is to install two catch cans to avoid that problem. I recently posted photos of that in the "K&N mods" title in the Z06 section.
You will find also alot of oil conducts through the front PCV loop (the little loop behind the TB). ALOT. The windage isolators inside don't block it. Same catch can is the solution.
Some mods I did: I also moved the rear PCV outlet away from the MAF area and into my TB spacer, so I get alot of vacuum there. I fabricated a restrictor for the front line. Thus, I still get my full vacuum to the crankcase, more in fact more than stock, but a fraction of the oil passes, well what does pass goes into the can. Also, I inserted check valves in each PCV line to keep the vacuum up.
Sorry to hear that. Even when hooked up correctly the oil spillage has been frequently reported. You still get similar oil spillage on high lateral accelleration. Then the oil loosens the glue on the hydrocarbon traps and the engine inhales them.
The solution is to install two catch cans to avoid that problem. I recently posted photos of that in the "K&N mods" title in the Z06 section.
You will find also alot of oil conducts through the front PCV loop (the little loop behind the TB). ALOT. The windage isolators inside don't block it. Same catch can is the solution.
Some mods I did: I also moved the rear PCV outlet away from the MAF area and into my TB spacer, so I get alot of vacuum there. I fabricated a restrictor for the front line. Thus, I still get my full vacuum to the crankcase, more in fact more than stock, but a fraction of the oil passes, well what does pass goes into the can. Also, I inserted check valves in each PCV line to keep the vacuum up.