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Not trying to play expert just a thought..

I was thinking are engines are definitely newer technology although the tune of it from the factory is so mild. I was thinking if you were to use AEM's Engine Management System along with a dyno you could tune the A/F ratio more towards performance amongst other aspects. Somethings telling me the reason are motors don't respond well at all to I/H/E is the tune is a massive bottleneck. I come from tuning cough...cough...mustangs. Part of the reason bolt ons and mods work so well, other than the fact the motor is 3 times the size is the computers are so flexible it's not funny.

The returnless fuel system started being used on mustangs in 1999, as our cars this was a huge hurdle at first although Paxton came up with a soloution to it which I'm trying to find the article on now. We need a company to get on our side here and solve the problem specifically four our cars.

Question- I'm kind of new to imports but I'm guessing our cars use a Speed Density system as opposed to a mass airflow system?

 
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I'm not exactly sure at what your getting at? But i was wondering if we could just change the fuel system and tweak the ecu ! Like a total overide! But as i a am not sure! I will have to get back to you!

 
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Speed Density System? Could you describe what that is exactly?

I think that we could tune a vast number of things with the AEM EMS. First off, get rid of the rev limiter. It's there for a good reason, but reving past 6,800 (or whatever the limit is) for a little while during racing can't be all that bad. Then again, maybe upgrading valve springs and what not would allow you to take it past 6,800 without any fear at all? Then there's the speed limiter (if it exists, I still don't know if there even is a speed limiter). Then there's the fuel maps. I guess these control fuel ratio and fuel levels for various rpm's. We could tune this to the maximum output of the injectors, especially in high rpm's to get a nice little boost in power. Then there's the tire size adjustment for the speedometer (something nice). Then there's other odds and ends that I just can't think of.

Anyway, if you're still wondering about how to deal with the fuel system then welcome to the club. I'm still wondering myself. Although I pretty much know what has to be done.

I have some questions too. The amount of fuel that goes into the engine is controlled by the ECU by modulating the injector pulse width. Why won't replacing the injectors with higher flowing units and the fuel pump with a higher flowing unit solve the problem?

 
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I'm getting at that the problem with our cars is not so much the returnless fuel system which can and will be dealt with in time but what the car really needs is someone to tune the ECU and I think we could find some hidden power. Honda didn't want to give power instead decided we should be able to drive to Alaska on a tank of gas.

 
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I think that we could tune a vast number of things with the AEM EMS. First off, get rid of the rev limiter. It's there for a good reason, but reving past 6,800 (or whatever the limit is) for a little while during racing can't be all that bad. Then again, maybe upgrading valve springs and what not would allow you to take it past 6,800 without any fear at all? Then there's the speed limiter (if it exists, I still don't know if there even is a speed limiter). Then there's the fuel maps. I guess these control fuel ratio and fuel levels for various rpm's. We could tune this to the maximum output of the injectors, especially in high rpm's to get a nice little boost in power. Then there's the tire size adjustment for the speedometer (something nice). Then there's other odds and ends that I just can't think of.

-You hit the nail on the head with that one Grey that's exactly what I'm talking about.

Anyway, if you're still wondering about how to deal with the fuel system then welcome to the club. I'm still wondering myself. Although I pretty much know what has to be done.

-I think I'm gonna call Paxton bust there chops about this one.


I have some questions too. The amount of fuel that goes into the engine is controlled by the ECU by modulating the injector pulse width. Why won't replacing the injectors with higher flowing units and the fuel pump with a higher flowing unit solve the problem?

-Even if you put bigger injectors and a bigger pump, the problem remains that the ECU still needs to be hold to supply the extra fuel. That is were I hope the AEM system will come into play or a custom chip with some dyno time.

Gimme a sec. on the Speed Density thing

 
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Speed Density= On Mustangs from 86-89 they used this system which is really a bad design. All the parameters as far as how much fuel, and how much air are preset into the computer. So for instance when you start modding the engine it really doesn't respond very well at all because it's not smart enough to realize that along with more air you need more fuel it would just keep giving the same mixture. Once you got to the point of cylinder heads the engine would barely run or function because the ECU didn't understand what the heck was going on.

Mass Air- Mass Air is like a genious compared to SD. It uses a sensor (which is a cylinder) right after the filter element where the air enters the engine to monitor how much air the engine is receiving. So as you add a filter, headers, intake manifold, cylinder heads the ECU would respond with the approriate amount of fuel and air, the A/F ratio would be maintained. Even when you maxed out your stock 19lbs injectors and say went with 24lbs injectors, this just gave the ECU more availability to fuel which it used. You can add a blower, twin turbos almost anything and the engine's ECU would respond on a fly with the right amount of fuel and air.

Granted I'm referring to Mustangs a lot but this system is used on BMW, Mercedes etc.

 
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Here's a pic of a MAS-

Text

 
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So higher flow injectors are higher flow because of what? I was thinking that the ECU supplies them with a signal and they open for a set amount of time. Their flow rate is in cc/min, so higher flow injectors would supply more fuel simply because the ECU opens the higher flow ones for the same amount of time as it opened the stock ones. You see what I'm getting at?

stock injectors:
X cc/min

higher flow injectors:
Y cc/min

fuel injector pulse width:
f(rpm) - function of the rpm

Let's say that we're at a certain rpm. Then the ECU is programmed to open the injectors for a time T. The amount of fuel injected into the engine with stock injectors is T/min * X cc/min. The amount of fuel injected into the engine with higher flow injectors is T/min * Y cc/min. See what I mean? As long as X < Y, then it seems that upgrading the injectors themselves will allow for more fuel to flow to the engine.

 
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Right, I thought that we had an air sensor near the intake. When everyone upgrades their intake they have to plug in that sensor. Isn't that used for metering the fuel?

 
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Higher flow injectors if I'm correct have the ability to flow more fuel. Like a 2 Liter bottle opening where the top twists on as opposed to a the opening on a straw.

Let's say that we're at a certain rpm. Then the ECU is programmed to open the injectors for a time T. The amount of fuel injected into the engine with stock injectors is T/min * X cc/min. The amount of fuel injected into the engine with higher flow injectors is T/min * Y cc/min. See what I mean? As long as X < Y, then it seems that upgrading the injectors themselves will allow for more fuel to flow to the engine.

-It would flow more fuel but would it flow more fuel with some thought behind keeping the A/F ratio right it would it just dump more fuel into cylinder and end up with some of not being burnt??

Could you explain Pulse width?? Is that how long the injector sprays for???

 
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Right, I thought that we had an air sensor near the intake. When everyone upgrades their intake they have to plug in that sensor. Isn't that used for metering the fuel? Text

-I'm not sure I've never installed a CAI/SRI or taken my airbox off to get a better look. Possibly although I've never seen a car that puts the MAS at the throttle body. I'll take a look tomorrow at that.

 
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if i'm not mistaken, our ecu adjust to new flow rate of air and i don't think honda use that speed density thing.

 
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I just installed my CAI over the weekend, there is two things that connect up to the pipe right before the throttle body - a return hose from the manifold and some sort of temperture/airflow sensor (although, I did have a mustang at one point and I replaced the MAS on it, this sensor on the civic looks different - it's just a little **** like thing. I wish I took a picture of it, but I didn't have a camera handy.) Hope this helps!

Edit - it's early in the morning, everyone is allowed typos [IMG]i/expressions/face-icon-small-smile.gif[/IMG]

 
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Blitz has already created a supercharger system for the 2000+ Celica, which BTW is limited by the same returnless fuel system that we are. Maybe you could just contact them and ask them what they did...I know it includes an ECU replacement and intercooler, and is almost 5000$ for 90hp to the wheels and over 100lbs of torque.

http://www.blitz-uk.co.uk/new.htm

Not to mention their engine is like 11.5:1 compression ratio, we could up the boost ALOT more...

 
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<< It would flow more fuel but would it flow more fuel with some thought behind keeping the A/F ratio right it would it just dump more fuel into cylinder and end up with some of not being burnt?? >>



Yeah, I guess not. If I'm correct that it would flow more fuel that is. I guess you could set up the fuel injectors to work optimally at only a certain boost pressure. You'de either need a piggy back electronics device or a re-programmed ECU to open the injectors for the right amount of time according to boost level.



<< Could you explain Pulse width?? Is that how long the injector sprays for??? >>



Yeah, that' s basically a term for how long the injector stays open.

 
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I'm gonna call Paxton since they are the ones that fixed the problem in the 99+ mustang. This returnless thing isn't really a big deal it's just no company has taken the time to deal with it. One of my pet peeves with the import aftermarket is it's not as mature as the domestic market as far as the innovative products that get released. Thanks for everyones thought on this it's helped a lot. Keep it coming.

Greg

 
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<< I just installed my CAI over the weekend, there is two things that connect up to the pipe right before the throttle body - a return hose from the manifold and some sort of temperture/airflow sensor (although, I did have a mustang at one point and I replaced the MAS on it, this sensor on the civic looks different - it's just a little **** like thing. I wish I took a picture of it, but I didn't have a camera handy.) Hope this helps!

Edit - it's early in the morning, everyone is allowed typos [IMG]i/expressions/face-icon-small-smile.gif[/IMG] >>

It's an " intake air temp. sensor" Honda has used them forever. Also yes Honda has used speed density systems forever too.

 
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Hey Mitch

It's an " intake air temp. sensor" Honda has used them forever. Also yes Honda has used speed density systems forever too.

-so are systems are a Speed Density system??