joeuser42

I have been trying to find as much info as I can about the way the onboard computer works in conjuction with the engine sensors and fuel injection. There is really not a lot of detailed info out there. At least not for free .

Let's take the C&L MAF system as an example:

The way I wish it worked:
The numbers I'll use are just an example. I have no idea what they really are. If the stock air inlet flows 500 CFM and the computer wants to maintain a 14.5:1 air/fuel ration, then adding a better breathing air intake that flows 550 CFM should just cause the computer to add more fuel by lengthening the fuel injector pulse until it has the proper air/fuel ratio. More air and more fuel means more HP.

The way I think it works:
I have seen mention of a fuel table as a parameter(s) that can be changed by a handheld tuner such as an Xcalibrator. From this I'm guessing that Ford says, "the stock intake flows 500 CFM and therefore we need X amount of fuel at a given RPM and temperature. The CFM of the intake will never change and therefore our fuel table will never need to change."

When you add the intake mod without a tune you increase the air flow, but the fuel table stays the same. Therefore, you get a lean condition and must use the tuner to adjust the fuel table. I don't know what effect using a higher octane fuel would have. I know higher octane burns slower, but I don't know if it is the equivalent of more fuel. Dang, I should have payed attention in my thermo class!

If it works the way I think (fixed fuel tables), then it explains why mods need a tune. However, I don't understand how the C&L intake could make more HP without a tune. Any thoughts?

EDIT: I found this post by LeeB99 of C&L, but I still can not finger it out!

wild stray

It could be that the computer will only make limited adjustments to a/f ratios and that we are (of course!) exceeding those perameters i.e., from what I've seen/heard, a better breathing filter might produce a little more power where-as the removal of the the air cleaner assembly entirely puts the hp in the dumps.

joeuser42

I PMd Scott (scothew) and he shed some light on it for me. One of probably many things I had wrong was "more fuel more air equals more HP".

From what I'm reading, there is a air/fuel mixture that is optimum for emissons and an air/fuel mixture that is optimum for power. If you take a stock stang and add a higher flowing air intake only, the MAF senses the increased airflow and sends a voltage signal calling for more fuel until the previous air/fuel ratio is acheived. I'm an electrical engineer and not a mechanical so I don't know if more fuel and air at the same ratio increases power.

What the C&L does is causes the MAF to send a voltage signal that corresponds to a smaller air flow than the actual . From C&L's web page it looks like it changes the ratio from 11:1 to 12:1. If bringing the ratio into that range is optimum for performance and produces an HP gain, then it makes perfect sense that the C&L can add HP without needing a tune!

The question that comes to mind for me is: "If I can change the air/fuel ratio with a tune to 12:1 and remove the HC trap, what additional gain does the C&L offer?" Lee claims there is an additional gain but I'm not sure how much. It seems like if you want a gain but are worried about your warranty and don't want to flash, then this is perfect for you. If you are going to flash and remove the HC trap anyway, then you would need to compare the C&L to plain cold air kits for their gains. My $0.02.

ZERO

your $.02 are probably a pretty good analysis. i was thinking about the c&L specifically because i wanted to avoid getting a tune. i would love to get the MMR, but i don't really want to have to buy the xcalibrator and get the car tuned. trying to hang on to my warranty in the event something goes wrong before 36,000 miles.

wild stray

I would like to know how much of a compromise the C&L ends up giving you, only to understand it as a mod. What a/f ratio do you end up with and how does it affect your engine. I can fully appreciate someone not wanting to take the "re-flash" plunge as it is expensive and with emissions testing and warranty considerations, can hang over your project like a black cloud.

adrenalin

Until the day I see someone's warranty voided because they flashed the computer I am not going to worry about it.

LeeB99

Hi all, This is Lee Bender. I was informed of this thread, and asked to put in a word of two.

Up until the 2003 model vehicles, the computers were not near as sensitive to air intake changes. In order to maintain a good air/fuel ratio, we simply make sure that the voltage signal that is being sent to the computer maintains a high enough reading to keep the air/fuel in line. In other words, even though the airflow available to the engine was being increased (which by itself can lean out the air/fuel), we had to make sure that the voltage was kept up at a level that would give us the air/fuel ratio that we were looking for with the higher flowing meter/inlet assembly installed. Depending on the vehicle, in many cases we could maintain the same basic voltage level as the stock air meter, but increase the airflow through the system. This would lean the air/fuel slightly, but that would typically be on cars that had a richer than ideal air/fuel as stock. Other vehicle applications would actually require us to raise the air meter voltage slightly above the level of the stock unit in order to keep the air/fuel where we want it.
In 2003, the computer's sensitivity became "enhanced". This was most noticable on the Mach 1 vehicles. Simply installing an exhaust or "cold air" filter system can lean the air/fuel out by a full point for each of those modifications. When you consider that the stock air/fuel is 12.2:1, you can see how a tuning solution (such as a predator that gives you personal control) has become more necessary with the newer vehicles. I suppose that this was a preview of things to come.

Our first 2005 Test vehicle (which you guys are aware of from our website) showed us that on the 2005 that things MIGHT be getting easier. After testing other vehicles, however, this does not appear to be the case. Even when using a MAF housing that is machined to be 100% IDENTICAL to the stock air meter body, the computer senses the increase in flow throughout the package, and leans the air/fuel out considerably (to around 14:1). We have never seen anything like this before when replacing the air meter on any Ford vehicle. And why we did not have this issue on the first test vehicle is why we must re-test on it, to get to the bottom of things. In fact, based upon what we have seen from testing since the first vehicle, I do not believe that any "cold air" system can be installed on the 2005 GT without tuning for proper results. There may even be issues with a drop-in filter in the stock assembly, since we saw such drastic changes while using a MAF housing that was identical to the stock unit.
Certianly, you can install a "cold air" system and the car will SEEM to run fine (and it will pick up SOME/ a little power), but for proper function and best performance with a good air/fuel, it appears at this point that using a tuner may be the only option. We have been working with Diablo on this, and they have a test vehicle with our system on it, and they have already worked out what needs to be done in order to make everything fall into place.
The reason why none of this information has been posted yet, is because 1) I still have some final testing to do to make absolutely sure that tuning is the only option and 2) I am not our webmaster, so I can't change what is on the website easily, and I didn't want to revise the information until we knew exactly what route we are going to take.
We have tried several different machined air meter designs, and with the exception of the first test vehicle, the computer seems to react pretty much the same. We know that this can be fixed through the handheld programmer, but I have some more testing to do, including testing with the new programmer to compare the results. If we end up selling the system with a programmer, it would come pre-loaded with several files that are configured for the complete air intake system, including the option for adjusting for upgrade exhaust systems. The beauty of having the programmer, however, lies in the fact that if you do other mods in the future, it allows for you to adjust the fuel and timing in these programs. This will give you nice flexibility for the future.
I know that this is really bad news for all of you who don't want a re-tune, but based upon our initial testing, it appeared that this would not be necessary. And John Kilmer and Greg (the guy who owns our first test vehicle) can vouch for me that it appeared that this would not be necessary. I still have a couple of things left to try in testing, but as of this moment, it appears that tuning adjustments will be necessary. The good news (for C&L) is that it seems that anyone else who sells an upgrade intake assembly will need tuning as well. I am sorry if this is dissapointing news to anyone, but I am doing everything that I can to make this product the best that I can. If tuning is necessary to achieve this goal, then that is the way that we will have to go...

Lee Bender
C&L Performance, Inc.

adrenalin

I had a feeling the C&L would need a tune. Thanks for the honest answer and great information.

joeuser42

Lee, thanks for taking the time to write that up. Also, thanks for giving an honest answer and not sugar-coating it.

The Boss Hog

I'll second that

The Boss Hog

wild stray

I appreciate what you are saying....and how you are saying it. I know everything on a new model vehicle can't be figured out "over-nite" and look forward to any future info you might pass along.

SixtySix

And a third!

Here's another question I have though. Are there any concerns with the temprature of the incoming air seeing that you are using an aluminum housing.

Probably not a concern for most, but since I live in the desert, summertime temps are extremly hot!

-FROG-

Just a thought..... maybe those living at higher altitudes will see a gain from a simple CAI install (no tune) since they are still within the parameters for A/F mix. Maybe not..... But I know here in Texas, my car feels pretty boggy with a cone installed. But Joe Blow in the mountains may get a little pep in his step with a cone install.

HOTLAP

And a 4th!! Thanks Lee for the straightforward explanation and I look forward to hearing your final analysis when you have finished testing :worship:

ZERO

5th.

Roger Ramjet

The way I see the situation:
OEM oxygen sensors are only good at part throttle cruise. All OBDII computer use that information then add a fixed fuel increase for full throttle operation. To keep the cat/cons alive the AFR needs to be around 11:1 at full throttle. When engine airflow is increased (via better intake or exhaust systems) the mass airflow sensor measures the increased airflow and the computer adds fuel flow to keep the part throttle AFR at 14.7:1.

Well, if the part throttle fuel flow is higher and at full throttle the computer adds the fixed increase the full throttle AFR is even richer than stock - maybe 10:1 or even 9:1.

Best power is usually around AFR 12.7:1. So, the bottom line is leave it alone or be prepared to reprogram. And, reprogramming for max power will shorten the life of the cat/cons.

dallasw77

Thanks for the info Lee! I am glad to see how everything is progressing with all the CAI systems. I wonder how the results will be when C&L and MMR are finalized with tunes.

Mongoose

Another thanks to you Lee.
How can one make a tune without an exhaust sample to know if you are lean or rich? I plan to retune mine also after all the mods are complete on a dyno with an exhaust sniffer. I feel this is the only way to do it correctly. What about this, Lee?

subzero05

that was a very informative post...thank you!.. I intend to monitor your progress on this closely as do all the others and Hope all ends up well.