[InjectorsPlus]

WHEW! Can someone read that over and tell me where I got lost?

I see too many "tuners" who don't understand what they are tuning or how the motor works tuning cars. It's not REQUIRED information but I believe if you understand the underlying theories about how this stuff comes together, the mystique of tuning kinda fits into place. It's not all black magic. It's not hard to do, but without experience and knowledge it's hard to do WELL. So our goal is to take the physics of delivering fuel into a combustion chamber and understand what that means to the ECU based on the sensors and conditions it is given, and ultimately, how much fuel needs to be deliered based on the feedback of those sensors.

All these sensors are, are indicators of engine conditions so the fuel can be put in or taken out. WHY do you put less fuel in a hot one vs. a cool one? WHY does the amount of vacuum change the amount of fuel you give. THOSE are the basis to understanding tuning, before you pick up a laptop.

thanks.

[Big_G]

Take a deep breath John...........now exhale. Feel better?....lol.:

[InjectorsPlus]

Originally Posted by Big_G

Take a deep breath John...........now exhale. Feel better?....lol.:

HA! In through the nose, out through the mouth!

Someone.....quick get me a bag.

[InjectorsPlus]

I'll pause here instead of dumping too much info.

Next up, sensors, as SLVR talked about and how each is related to the other. Inputs first. Then outputs.

[slrvette]

Exactly!
The only output that hasn't been explained yet is the IAC.
Anyone?

I think that this is coming out perfect. Very simple and basic for the beginner so you don't feel overwhelmed the first time you look at the datalog like I did!...lol
Almost ready to datalog?

[InjectorsPlus]

Originally Posted by slrvette

Exactly!
The only output that hasn't been explained yet is the IAC.
Anyone?

I think that this is coming out perfect. Very simple and basic for the beginner so you don't feel overwhelmed the first time you look at the datalog like I did!...lol
Almost ready to datalog?

IAC...as it says....IDLE AIR CONTROL

When you make a mixture more rich or lean it effects the idle. By opening the throttle plates, the idle can go up and down if you add more air in, or take air out of the mixture.

The car has to idle at a particular RPM under numerous conditions. The IAC does that.

For example, if your in neutral, the load on the engine is zero and the idle will be what it is.

What happens when you turn on the air conditioning? The computer know the idle should be say 1000 RPM. So it makes the idle 1000 RPM. When you go from Neutral to gear, the motor steps down again, so the IAC brings the idle back UP to where it's supposed to be.

How does it do that? Well picture a screw inside a pipe. The screw has a cone shaped head called a Pintle. The pintle fits inside the pipe which is also cone shaped on the inside. So the screw goes in and out of this cone shaped tapered recess in the pipe, depending on the idle.

So the ECU is looking at the INPUTS, sensors, and the RPM and saying......HMMM....the RPMs are high/low based on the input of the sensors I need to add/subtract air.

There is a hole in the throttle body which is opened or closed by the IAC moving in or out. When the IAC retracts the pintle the hole is opened, allowing more air into the system, raising the RPMS. When it is closed, the mixture is richer.

So it, the ECU, backs out, or runs in, the IAC until the idle meets the pre programmed designated idle. Once there, it stops.

[InjectorsPlus]

Originally Posted by InjectorsPlus

Now think about what is happening, you have VE in filling a specific size cyl with a specific amount of air and fuel. This is called FUEL SUSPENSION. Again, this is more reliant to intake runner design which allows the droplets of fuel to remain a mist and not condense or consolidate within the fuel path.

So your question is, who gives a rat's butt....

It is important to understand those 10,000 foot theories in order to get a better grasp on what you are trying to accomplish with a tune.

The optimum most efficient use of fuel is called stoichiometric reaction which leaves a 14.7:1 ratio of oxegen to burned fuel. The goal when tuning is to try to keep with that number.

Now that rule is not hard and fast. In my car for example I idle lean, at 15-16 AFR. WHY? The cam likes that. Under acceleration or power requirements you should expect to see 11.6-12.3 for optimum power. at WOT it shouldn't drop below 11.

The lower the number is, the richer the mixture is.. So 17 is leaner than 13.

Something I wanted to comment on here. Fuel suspension is important because an intake/head that promotes better fuel suspension will require different tuning parameters than a head/intake where the QUALITY of the air flow sucks.

That is why I say it's not all about flow numbers for heads, but the quality of the air that is delivered.

The ability to suspend more fuel in the air will result in more power and different tuning nuances.

THIS IS IMPORTANT!!!!

The reason is because I see a lot of people ask "what size injectors do you have".....and responses that say....I have XXX on my motor.

Well, if their heads have BETTER QUALITY NOT QUANTITY of air flow, you will need to deliver LESS FUEL to get better results. It CAN effect both the tune, and the size of the injectors. That's why sizing isn't hard and fast. But the ECU allows you to tweak that, as does your fuel pressure.

Each combination is unique.

[InjectorsPlus]

I bought up another dynamic here in the last post. Fuel pressure.

Fuel pressure is important in tuning because it will effect how you tune as it will effect the flow of the injectors.

This is exactly why INJECTORS PLUS is more than injectors. All these elements come together to result in the correct FUEL DELIVERY SYSTEM. As I had said in the past injectors are like gum at the checkout line, the crap next to the mints and national enquirer while you stand behind someone with 25 items in the 10 item express lane. That's why you don't see Sea Foam or Injector Cleaner on my site, Autozone has it you can get it there, we stick to the meat and potatoes of how this stuff works.

There are serious considerations to the entire system when building a high performance motor, and they ALL effect the tune.

For example using a fuel pump that has -10 AN in and -10 AN out may have the tendency to run dry or experience cavitation. This will result in poor fuel pressure and effect the tune. The solution, use -12 in and -10 out a lot of times.

Which regulator you choose can determine the performance of the system. It has to be matched to the pump you're running. Just had a guy running a carb regulator on an EFI motor and wondering why it won't work. This again, WILL EFFECT THE TUNE.

Fuel pressure too will dictate what injectors you use. For example, I have sold Seimans injectors for very high performance applications, and very expensive motors. I have no problem with that. These are motors that run $50-70K just for the motor. Seimans are good injectors.

On the other hand I have a customer who has a forced air IMPALA he runs on the street not worth $15K. If I had my preference I'd put him into BOSCH. WHY? The Seimans are a great injector, but under FP of 60 pounds or so and up, the pintle vibrates and they fail. He melted a piston.

What we did was open his 60s to 80s when we rebuilt them to allow him to get the tune and lower his fuel pressure to ensure safety.

I think my point is, as evidenced by IP's tag line here "HIGH PERFORMANCE FUEL DELIVERY SYSTEMS" the tune is the LAST STEP in dealing with what you're going to require to get the car to run right, not the first.

Although injectors are that "gum" it's good to understand which product and which size is the right fit and the implications of choosing one injector over another for any given application. It's far more than "application and flow please".....that's where advice based on experience and knowledge can save you a lot of time and headaches in your tuning.

[InjectorsPlus]

Flow matching...something else that effects a tune.

We hand match every set of injectors that leaves our shop. We buy a box of 300 injectors and the manufacturer says "flow matched" on the box. Don't believe it.

There is "flow matched" and "FLOW MATCHED". Some vendors will tell you a set of injectors is flow matched simply because it says so on the box. They reach in and grab a bunch and toss them in the bag and out the door we go.

Well, our experience tells us that whatever is printed on the box is not necessarily the truth. We hand pick every single injector we sell and flow match ever set on the bench before they leave the shop.

Why is this important? Well first, many of our customers have VERY expensive motors.

Second, if you don't have a truly flow matched set, it makes the car MUCH harder to tune. Inconsistencies in injectors can screw with the AFR the O2 sensor is picking up and you can wind up with some lean and some rich cylinders.

I can't afford to have customers blowing up motors, and the fact of the matter is the slight increase in cost for a truly flow matched set, will be off set by the time you save trying to tune, by a long shot. Professional tuners can save 2 hours on a tune between a flow matched set and not. Not MY numbers, theirs.

Think about what that means to the amateur.

[InjectorsPlus]

BTW, SLRV, all this is stream of consiousness. I am writing off the top of my head with no planing or fore thought.

If it's disjointed or needs re arranging, feel free.

I apologize for digging so far down the rabbit hole, but I think it's required to understand the SYSTEM before talking about how to tune it. Bottom line tuning is the last part in fuel system design and without a basic understanding of the elements that get you to that tuning, it's harder to understand.

if you think of tuning as simply trying to get the right AFR under certain loads, temps, timing conditions, it's not all that magical.