I am confused. When I first got my chip form JDM I was told that the valve breather cap is highly important and that the chip has to be calibrated for it. I called them now on two separate occasions and spoke with Shawn and Jeremy that my SES was apparently caused by a P0171 code. They told me to put the stock oil cap back on. When I asked them if I needed to send my computer back for a reburn they said it wasen't necessary! What gives? First I was told that it needed to be burnt for the breather cap, and now that I put the stock oil cap it doesen't need to be reburnt? What gives?

 

 

Can anyone please answer this question?

 

When I got my Lightning, I sent my superchip chip to JDM to have it reburned for the new L, at the same time I bought a breather cap and had them program the chip for it. When the weather started to get cold I removed the breather cap and put the stock cap back on, I emailed JDM and asked if it would be a problem, and they said that there would be no problems by removing the breather cap.

Not much of an answer for you, but its what they told me.

Larry.

 

The Breather Cap allows UN-METERED AIR into our system. This can cause a lean condition so thats why everyone says get a re-burn. I ran mine over 6 months with no reburn and no problems. A tuner will richen it up a tiny bit but it's hard to adjust for it because they really don't know how much UN-Metered Air is getting in. IT'S UNMETERED and not going through the MAF, so it's more of a guess without having it on a Dyno.

So to answer your question, NO PROBLEM taken it off because IF ANYTHING it will make it a tiny bit richer. Rich is safe, especially in colder months.

 

Rob

Your right on the money, thats why I took mine off, because of the cold weather.

Larry.

 

how is unmetered air entering the crankcase going to affect the air/fuel mixture

 

Because the unmetered air doesn't just enter your crankcase. It gets puled into the intake from the crankcase under vacuum.

Coldie

 

Thanks Coldie

TZRLightning01 think of it this way, the Maf is constantly adjusting A/F based on the flow of air GOING THROUGH THE MAF.
If all of a sudden air goes in the back door, what happens ???
"IT DOESN'T RICHEN UP THE MIX"

Please realize A/F is probaly the most important issue of our L's, one bad tank of gas, a clogged fuel filter, or too hot of a plug, can ALL burn AND DESTROY our motors IN SECONDS under certain conditions.

 

I came up with a way to allow psi to vent under boost conditions and to have the crankcase in a vacum[over12in cruising]so I have the best of both.Came up with it when I installed a vortech on the Gen 1 I have.It pressurized the crankcase over 1/2 pound and that caused the dip stick tube to act like a spray can.since I race it on open road and open track events I knew that would not work.so did some testing and can up with the first version of my idea which is still on the truck [have not found any better, or made anybetter]Used the same idea and principals on the 99 and it works .
If you run with the stock cap on and the chip was burned for vented you will or should be running ABOUT half a piont richer.Stan

 

I understand that the breather allows air in that isn't metered by the MAF, but this is only under vacuum conditions, i.e. CRUISE, not WOT. When the engine is running less than WOT don't the O2 sensors tell the computer to richen the mix, therby bringing the A/F back to stochiometric ratio? Only at WOT does the computer ignore the O2's, and by then you are at boost and the breather won't be pulling any air in, it will be expelling any excess. By this reasoning the breather won't affect the A/F ratio.

What am I missing here

 

You are not missing anything I am not going into all the detail.The computer can richen up the mix to a point there are parameters that it has for stay in [Fuel Trim] if it is within those setting the lite will not be on but if it goes outside of them then the EEC turns the ses on.Aslo keep in mind that as the throttle angle changes so does the load and that affect those numbers also.Stan

 

Stan, could any damage be caused by running a half a point richer?

 

Not that I know of.Cats might get alittle hotter than normal but if anything it is safer to be rich than be on the lean side.Stan

 

Thank you Stan