I just read your sig and though it was funny cause yesturday my OnStar light was red alll day. Then today is was green...it like alternates...

 

Hahahahahaha!!!!!! Well, RYRO14's did the same thing. We have NO idea why.... So he said that one day, and I said that's sig worthy.

Mine has always stayed green... :shrugs:

 

When you call names because you are too ignorant to realize when someone is giving you useful information, thats immture.

Thats obvious that you don't know much. Otherwise you wouldn't be arguing with the principles of how your car works. It doesn't matter if it "seems fine", you do a lot of bad things to the car that "seem fine" at the time and then cause problems down the road. As a technician, I am very familiar with powertrain control systems. What you are doing by running an atmospheric blow off valve is skewing the data that the PCM is reading from the sensors. As I already explained, this will throw off the MAF readings, STFT's, LTFT's, O2 readings. If you don't even understand how any of this works, how can you sit there and say that its not doing any harm?? Thats ignorance.

Do what you want. But when something does go wrong as a result of your hack work, you'll be the first person to go off on a tirade blaming everyone else.

 

JPizzles car runs fine. No codes, still dynoes as high as everyone elses with similar mods. Why all the hate?

 

my onstar does that lol its green one day then red the next...:shrugs:

back on topic...i personally like the sound of the bov VTA...but if i must ill jus stick with the stock bpv for now till theres a fix for this

 

Because it doesn't "run fine". He thinks its running "fine", but its not. Dyno numbers don't mean anything. What he's doing will not affect his peak power, it will affect part throttle driveability. Nobody is "hating", we are trying to explain to uneducated people that what he is doing is not correct, and has the potential for bad results.

If you understood powertrain control, you'd realize that under wide open throttle, the PCM goes into open loop and determines fuel trims based on preprogrammed tables, not wideband O2 feedback. Its under part throttle that he is skewing his driveability and fuel trim calculations.

And when something happens to his engine, GM has every right not to cover it.

 

I have no part throttle driveability problems. It feels & acts the same as stock during part throttle acceleration. I'm not asking GM to cover it if something breaks (although I'm not exactly sure what would happen to my engine)...

Could you please explain what would happen to my engine? Bent rods? Too rich? Too lean? Cracked piston ring?

What would happen to my engine? I'm asking, because I don't know.

Thanks!

 

What you are doing by running a BOV is venting measured air.

So lets say the MAF reads that you have 150 g/s of air entering the intake at idle on a stock engine. The air goes past the MAF sensor, enters the turbo, flows into the charge piping, and enters the engine for combustion. Now lets say you install a BOV. The MAF reads the same 150 g/s of air, it flows through the turbo, into the charge piping, and then you close the throttle - poof, the air it vented to the atmosphere. So now only 100 g/s (for example) are entering the engine, instead of the 150 g/s that the MAF measured.

See the problem with this so far??

So now the MAF measured 150 g/s, and only 100 g/s (for example) made it to the engine. The PCM calculated the fuel trim based on the fuel table for 150 g/s, so now you're adding fuel for 150 g/s when in actuality that is not the amount of air entering the engine. Combustion takes place, and the exhaust is measured by the wideband O2 sensor. The O2 sensor determines that there is not enough oxygen for the amount of fuel that was burned based on the oxygen content of the exhaust. The PCM sees this reading, leans out the fuel trims (not good) and then applies it to the next combustion cycle. On the next cycle, the BOV doesn't open (cruising, for example) and the MAF measures the proper amount of fuel to be comsumed. However, the fuel trims may have been modified already, which now causes a lean condition.

See how this confuses the PCM??

So now the PCM sees the STFT (short term fuel trims) return to normal, since it sees that it needs more fuel than it had previously adjusted to. This cycle continues, and all is does is skew the MAF readings (since the PCM can't trust the MAF) and throw off the fuel trims (LTFT's especially). This results in a car that does not run properly, does not run optimally under part throttle, and does not get ideal fuel economy.

As for long term effects, running rich can overheat the catalytic converter, cause washdown of the cylinder walls (which causes cylinder wall wear and ruins the oil), and will affect your power and fuel economy negatively.

Hope that helps you understand.

 

im just going to wait till everything is figured out with the maf and keep running my bpv and upgrade the spring for now

 

The only reason these cars are running half way decent with VTA vs other cars is the way the GM OS uses the MAP to equalize out lower MAF signals.

Still not right.