cold air intakes and MAF meter

[zmerun]

I have been talking to xtreme motorsports about potential issues with a cold air intake (is Vortex Rammer) on a stock '03 Z06. I was told that some of the '02s and '03s car run lean with the cold air intakes because they don't have a screen in the MAF meter. This bothers me because I don't believe it would be easily identifiable without having it checked out. Any insight on this would be appreciated!

[BLEUBYU]

My Vortex has been installed for nearly two years with no problems. Of course, as with many of these intakes, an LS1 Edit session is needed to really take advantage of them. At the time I bought my Vortex, there were only two real cold air options available, and the other one was mounted too low for my personal comfort level (hydrolock concerns).

Although I am satisfied with the Vortex, if I wanted to purchase a system today, I would probably go Vararam since I believe it is superior to the Vortex as speeds increase.

My $.02...

[Wingnut]

IMHO I believe it's the opposite situation. The computer thinks lean so adds fuel and you are actually too rich robbing you of potential HP without tuning.

I too run the Vortex...no problems but got a Vararam at a good deal which I wanted in the first place and will be switching along with several other mods soon.

[zmerun]

i don't know of anyone who could do the tuning here in piedmont are of NC. i don't want to run lean or rich - defeats the whole purpose of adding an intake. For the members who haved switched to a cold air intake, have you also changed the accordion air duct to a silicone one? I know if you buy a new air bridge that most of them come with one.

[Wingnut]

Originally posted by zmerun
i don't know of anyone who could do the tuning here in piedmont are of NC. i don't want to run lean or rich - defeats the whole purpose of adding an intake. For the members who haved switched to a cold air intake, have you also changed the accordion air duct to a silicone one? I know if you buy a new air bridge that most of them come with one.

You will have more HP than not running the aftermarket intake. I didn't say you would lose HP by switching. I was just addressing your question about being lean...you're more likely to be rich. You would have to tune to get full potential with any mod is all I'm saying. Slightly rich is better than too lean IMHO. Yes I changed the accordion air duct as well.

[zmerun]

so the computer can' t compensate enough on its own for the cold air intake?

[Wingnut]

Originally posted by zmerun
so the computer can' t compensate enough on its own for the cold air intake?

Yes it does do a relearn to adjust. I was originally addressing your "being to lean" concerns. I just said you're more like to be slightly rich than lean...but safe and ok. IMHO. Find one you like and buy it.

[zmerun]

just to make sure i am clear - i understand that the computer will make adjustments the best way it can, but what will something like an ls1 edit do? Is this what most people refer to as "tuning" when they make a change such as the cold air intake? I don't want to get the rammer and not achieve the full potential.

Thanks for the input.

[No Doubt]

When you add an aftermarket intake the long term fuel trims often go lean. The PCM can compensate for this condition up to a point (23% positive to be exact) and all is well as it will maintain a 14.7:1 air-fuel ratio.

If you log data using a program like AutoTap, EFI Live or EASE, etc. you will see that your LTFT's are positive numbers. This indicates the PCM is seeing a lean condition and is adding fuel to compensate. All is well though at this point and no power is being lost.

However, and this is the catch: once you go wide open throttle the PCM is no longer using the O2 sensors and other means to determine the proper air-fuel ratio. This is known as open loop mode. It uses a table (RPM vs PE) to lookup how much fuel to use for a given RPM. At this point it will add whatever amount of fuel was needed during closed loop in order to maintain the 14.7:1 AFR in addition to the amount specified in the RPM vs PE table. This causes a rich condition at WOT and therefore a loss of power, or at least not as much as you could get if the AFR was corrected (typically leaned out) using LS1 Edit and a wideband O2 sensor on a dyno.

I hope that makes sense.

[zmerun]

that is a very good explanation. prompts me to ask one question since I am not familiar with the process - when you mention a wideband O2 sensor, does this mean that this type of O2 sensor would only be used during the tuning process? What would it cost to get something like this done?

[No Doubt]

Yes, a wideband O2 sensor is used to determine the air fuel ratio during tuning. There are typically two ways this is done. One (and the best method, imo) is to use a wideband O2 sensor that plugs into a bung hole that has been put in the headers before the CAT's. That is between the engine and the CAT. This requires a bung to be welded in your headers and plugged when not in use.

The other method is to use a tail pipe sniffer. No bung is required. However, these are arguably not as accurate.

A third method, and more involved, is to obtain a portable wideband O2 meter and install a bung in your header. Then you can carrry it around with you as you drive. Onboard AFR meters are pretty cool.

The reason for this is the stock O2 sensors are not really accurate at anything other than 14.7:1 AFR, or very close to it.

As to cost a typical LS1 Edit tuning using a dyno is typically as much $500. It all depends on who does the tuning. Some of them offer free re-tunes should they be needed. (say you added more mods)

You can also buy LS1 Edit yourself ($550) and do most of the tuning on the street before going to a dyno to tune for WOT. However, this requires logging software such as AutoTap, EFI Live or EASE, and a laptop computer. And most importantly the knowledge of how to use these tools correctly.

[Wingnut]

No Doubt thanks for explaining in detail.