Chip programmed for Breather but........
Thread Starter
|
Registered User
Joined: Sep 2000
Posts: 353
Likes: 0
From: NJ
Chip programmed for Breather but........
My chip is prgrammed for the oil breather (whatever is done for that?) but my truck seems to run smoother at idle and under partial throttle with the regular oil cap on? I even notice it as soon as I put the cap back on. I have an ATI supercharger also. Should I just leave the breather or the original cap? Since the chip is programmed for the breather will there be any ill effects from putting the stock oil cap back on? Thanks.
Former Sponsor
Joined: Mar 1998
Posts: 13,385
Likes: 4
From: Virginia
Hi Silver X,
Briefly.......................
The breather cap installed in place of the oil fill cap in the passenger-side cam cover is used to vent crankcase pressure. It is typically added anytime our customers have made significant power gains, so it's a very common thing we'll do with a supercharged engine, for example.
This is not a new idea at all, we were doing this 30 years ago on non-fuel injected engines, and I'm sure others did it long before that.
However, there is an important "side-effect" on tuning from using that breather cap on these computer-controlled engines, which have control systems that allow us the ability to finally compensate for the effect of the breather cap on tuning.
The effect of using that breather cap is that unmetered air enters the engine under idle and cruise conditions, meaning air that does not pass thru the MAF (mass airflow meter/sensor), which will cause the motor to go lean under those conditions. So the A/F (air/fuel) ratios must be compensated for this in a custom-tuned chip, to allow more fuel under idle & cruise conditions.
We have done this for many F-150's, using everything from Eaton to ATI to Vortech to Powerdyne to Holley to you name it for superchargers, and this has not caused idle deficit in any of our customer's vehicles that we have either witnessed or that has been reported to us so far that I can remember off the top of my head, nor is there any idle deficit in our own supercharged vehicle. The idle still as smooth as the idle in any mod-motor will be in the vehicles we do this to, so we're not seeing any problems from using the breather cap as long as it's tuned for properly.
Removing the breather cap will result in running a little bit rich at idle & under cruise conditions, basically anytime the engine is under no load or very light load, as that is when the additional fuel is brought in to compensate for that breather cap allowing unmetered air to enter the engine, leaning it out a bit during no-load to light-load operations. Removing the breather cap will also probably result in pulling more oil up into the throttle body, and depending on just how much oil travels up into the throttle body, it can enter the engine and slightly contaminate the incoming A/F mixture.
I wouldn't remove it, but that's up to you, it's not going to cause a major problem for you to be a little bit rich at idle & cruise.
You might also want to go over *all* vacuum hoses, connections & fittings thoroughly, to make sure you do not have even the slightest tiny hidden crack in a hose, connection or fitting, as a very small vacuum leak can also give you a rough idle that more fuel can sometimes "bandaid," meaning improve it.
If we tuned that vehicle for you, or even if we didn't & you would just like to talk to someone knowledgeable about this, don't hesitate to give us a call to go over this in more detail, ok?
Good luck!
Briefly.......................
The breather cap installed in place of the oil fill cap in the passenger-side cam cover is used to vent crankcase pressure. It is typically added anytime our customers have made significant power gains, so it's a very common thing we'll do with a supercharged engine, for example.
This is not a new idea at all, we were doing this 30 years ago on non-fuel injected engines, and I'm sure others did it long before that.
However, there is an important "side-effect" on tuning from using that breather cap on these computer-controlled engines, which have control systems that allow us the ability to finally compensate for the effect of the breather cap on tuning.
The effect of using that breather cap is that unmetered air enters the engine under idle and cruise conditions, meaning air that does not pass thru the MAF (mass airflow meter/sensor), which will cause the motor to go lean under those conditions. So the A/F (air/fuel) ratios must be compensated for this in a custom-tuned chip, to allow more fuel under idle & cruise conditions.
We have done this for many F-150's, using everything from Eaton to ATI to Vortech to Powerdyne to Holley to you name it for superchargers, and this has not caused idle deficit in any of our customer's vehicles that we have either witnessed or that has been reported to us so far that I can remember off the top of my head, nor is there any idle deficit in our own supercharged vehicle. The idle still as smooth as the idle in any mod-motor will be in the vehicles we do this to, so we're not seeing any problems from using the breather cap as long as it's tuned for properly.
Removing the breather cap will result in running a little bit rich at idle & under cruise conditions, basically anytime the engine is under no load or very light load, as that is when the additional fuel is brought in to compensate for that breather cap allowing unmetered air to enter the engine, leaning it out a bit during no-load to light-load operations. Removing the breather cap will also probably result in pulling more oil up into the throttle body, and depending on just how much oil travels up into the throttle body, it can enter the engine and slightly contaminate the incoming A/F mixture.
I wouldn't remove it, but that's up to you, it's not going to cause a major problem for you to be a little bit rich at idle & cruise.
You might also want to go over *all* vacuum hoses, connections & fittings thoroughly, to make sure you do not have even the slightest tiny hidden crack in a hose, connection or fitting, as a very small vacuum leak can also give you a rough idle that more fuel can sometimes "bandaid," meaning improve it.
If we tuned that vehicle for you, or even if we didn't & you would just like to talk to someone knowledgeable about this, don't hesitate to give us a call to go over this in more detail, ok?
Good luck!