Running Lean A Lot With Front Mount?!

[maxperformance]

About a week ago i got a greddy front mount on my eclipse, my car has been tunned with the afc before it, and was running great. I didnt get it retunned after the installation of the front mount due to insufficient funds ya know.

Now at idle im dead lean and under full acceleration in higher rpm (mostly) the car runs dead lean I have stock injectors (with a Big16G) and a walbro 255 fuel pump. Should i deffinatly get it retunned now that i have a nice front mount? (I wish i knew how to fix the settings in the SAFC, money it so tight right now) Thanks for your help

 

[Ronin17]

How much boost you running?

 

[TheDeer]

You def need to do something about it, running lean will net you a melt down sooner or later. Probably sooner, at least richen it up(till you get it tuned).

 

[SpoOLxExO]

Well, the first thing you need to know, is are you really running lean or not.
Cause Autometer A/F guages are :thumbdown:

In the autometer's case, it takes a signal off of the stock narrow band o2 sensor.
This as you might have noticed, moves up and down the guage like a runaway train.

This probably doesnt mean that its running lean, but that the stock o2 sensor is on its way out, or out already.

Adding a FMIC doesnt make your car leaner, it cools the intake charge you already have, if anything it will make the car run a little richer due to the pressure drop associated with larger FMIC's. (Taking the same amount of airflow longer to reach the engine)

You need to check your stock o2 sensor, your wiring of the "A/F" guage, and all piping connections and clamps.

Its prolly somthing dumb, don't worry!

 

[CanadianTSi]

Buy a logger and Tune it yourself

If your on the stock injectors there's not much you can tune anyways, just keep the boost under 15psi and you should be fine.

 

[sickgsx-316]

Spool-
You are correct on some fronts but a bit shaky on others. Autometer A/F gauges, stink, do read off narrow band which is definetly not accurate. However, if it is reading lean, and his o2 sensor is in decent shape and not on its way out, it would mean he is running waay lean, dangerously.

A front mount actually does make your car run leaner. It does this by significantly increasing the amount of air going into the motor, (think, stock sidemount/piping versus new bigger fmic with hard piping and smoother bends), and when you increase the airflow and dont compensate for it with additional fuel, you will indeed run leaner. Your stock injectors are more than likely at max duty cycle.

You definetly need to richen things up, especially up top, on the afc. You also need more fuel, there is the B&M Command flo, like 30 bucks, that may give you a small margin of safety, you also need to rewire your fuel pump with maybe 8 or 10 gauge wires. Your 255 probably isnt even running to its fullest potential. You can find a kit on ebay for less than 30 bucks shipped, just do a search for DSM FUEL PUMP REWIRE KIT. What you really need tho, is bigger injectors. If you plan on staying smaller than a 20G than 550's will suffice.

 

[awdsm drft]

Um, you want to explain that again?. Frontmount will not affect a/f other than allowing for a cooler and therefore more dense charge.

forget about your a/f gauge, its useless. Pull a plug, the one closest to the timing belt. If its white you're lean.

 

[SpoOLxExO]

Spool-
You are correct on some fronts but a bit shaky on others. Autometer A/F gauges, stink, do read off narrow band which is definetly not accurate. However, if it is reading lean, and his o2 sensor is in decent shape and not on its way out, it would mean he is running waay lean, dangerously.

How "Dangerous" is a 16g at stock boost with a HUGE Fuel Pump like the Walbro 255? Besides, I had a wack A/F guage like that, and the same thing happened, it was the o2 sensor. You are just guessing...

A front mount actually does make your car run leaner. It does this by significantly increasing the amount of air going into the motor, (think, stock sidemount/piping versus new bigger fmic with hard piping and smoother bends), and when you increase the airflow and dont compensate for it with additional fuel, you will indeed run leaner. Your stock injectors are more than likely at max duty cycle.

Yeah, thats a good theory, but it does NOT "Significantly" increase the airflow, because it is the TURBO that makes the air, not the intercooler. Search Effiencey, Pressure drop, then come and chime in...

You definetly need to richen things up, especially up top, on the afc. You also need more fuel, there is the B&M Command flo, like 30 bucks, that may give you a small margin of safety, you also need to rewire your fuel pump with maybe 8 or 10 gauge wires. Your 255 probably isnt even running to its fullest potential. You can find a kit on ebay for less than 30 bucks shipped, just do a search for DSM FUEL PUMP REWIRE KIT. What you really need tho, is bigger injectors. If you plan on staying smaller than a 20G than 550's will suffice.

The Walbro 255 pump is WAY too big as it is, so now you suggest increasing the base fuel pressure with the B&M modifyer, which only allows you to raise the Pressure. With a huge pump, you're still over-running the fuel pressure regulator, thats bad. :laugh:
You have not been into this very long, thats obvious.
If he even needed an AFPR, it would have to be an aeromotive unit, or one of the new generation bolt on adjustables, with a guage. Base fuel needs to be around 38psi-42 psi.
But as the other guys have stated, logger, or check your plugs.

I still think its the o2 sens or the fuel filter, so we'll see...

 

[awdsm drft]

larger fuel pumps acomplish NOTHING, on stock fuel lines and fpr.

first fuel mod should be afpr along with 5/8" inner diameter lines throughout.

 

[sickgsx-316]

I've been into this for a long time, and speak from experience. I have the walbro 255 in my car, and when i hit the blinker the voltage drops and I can hear the fuel pump whine, telling me it is not receiving enough current to work properly.

I completely agree that it could more than likely be a wack o2 sensor. I never said it wouldnt, the guy never said how much boost he was running (or I missed it). I doubt he is in any real danger of being lean, but he is at a point now where he should start considering upping the fuel and dialing things in. Talk to any race shop and they will tell you that most narrowband a/f gauges tell you its lean when its too late, and are a waste of space, and to hock it for an EGT gauge.

The stock intercooler impedes flow, where as a front mount doesnt. Front mounts typically add 25+hp, and all they are doing is adding air.

The guy is broke, he can get the B&M unit, with a gauge, for less than 45 bucks if he look, and it does its job fine. The aeromotive units are way expensive, and defiently a superior product.

If you raise the base fuel pressure with the modifier there will be more up top. I am just offering inexpensive ways to get more fuel into the motor. Its what I would do, and most people I know. Its always better to run on the rich side for safety reasons than even risk running lean until you have the proper fuel management (wideband o2) and an EGT gauge.

It seems to me like you are claiming that the only thing that affects air fuel ratio is the turbo and how much boost you are running. I would have to disaggre with you there. Air fuel ratio...stoich is like 14:1 14 molecules of air per 1 molecule of fuel. If you add exhaust, port something, anything that allows the motor breath more freely, you are then dicking with that 14:1 ratio because there is more air going through the system, and in essence running leaner, and need to tune to those mods. Its a big deal where I am at because I live in cali, with crappy barely 91 octane, where u shouldnt run too much boost unless you have lots of fuel for it. In other parts of the country that offer the 93 octane you can get away with putting off fuel mods a bit longer.

I dont mean to butt heads with you bro. The bottome line is this guy is worried about running lean, and IMO, with his current mods, he probably isnt now, but with further mods he will be soon and needs to think about getting more fuel, especially if he is running crappy cali fuel. (dont know didnt bother to check profile) We are both right in certain respects.

 

[maxperformance]

Look I really appriciate everyone taking the time and helping me out here. I know I need bigger injectors. Right now im only running 12 psi, so im taking it kinda easy. And the Autometer gauge might be unaccuarate, I understand there might be a problem there. But the thing that bothers me is that sometimes when I am under real heavy load or acceleration in 2nd gear the car backfires and pops. I immediatly let off the throttle. I think it is because of the stock injectors, probly at max load. Im thinking about getting RC 550cc for myself.

 

[coltboostin]

larger fuel pumps acomplish NOTHING, on stock fuel lines and fpr.

first fuel mod should be afpr along with 5/8" inner diameter lines throughout.

Your funny. People run WELL over 400whp on stock fuel lines and stock regulators, but NEVER with a stock pump. Dont give this guy advice that will have his motor poping in no time flat.

If I may ask, scine big pumps do niothing on stock lines/regulator, what times are you running with your stocker?

 

[awdsm drft]

Ugh. Please refer to the bench flow testing of the stock fuel system, its under fuel on www.vfaq.com.

Giant increases in fuel pressure only allow for tiny raises of flow at the line. Stock injectors greatly outflow the stock fuel lines. And a few pump with almost three times the flow translates to 3-5% increase at the rail.

Simply put, the pump is not the worst part of the system or most restrictive. I myself have a 190lph pump and am a huge hypocryte!

Could you please point out some people who have my 400hp on stock lines and fpr? I do not think its possible.

 

[91PlyLaser]

my friend boostin4g63 is pushing around 400 at the crank with a 255lph and 650's with NA fuel pressure regulator and stock lines with no problem. wtf maybe a fpr is needed but the lines are fine.

 

[Blk_99gst]

Reading this thread and seeing how much bad and incorrect information was posted in here made me sick. So I'm going to list the flaws:

Adding a FMIC doesnt make your car leaner, it cools the intake charge you already have, if anything it will make the car run a little richer due to the pressure drop associated with larger FMIC's. (Taking the same amount of airflow longer to reach the engine)

You got the "cools the intake charge" part right, but you are wrong when you say a fmic doesn't make you leaner. If you have your safc settings tuned for the air temp and air density from a smic, then you switch to a fmic which will provide more dense usable air at a lower temperature, you need more fuel to compensate for the more usable air. So if you don't change your high safc settings, then you will be running lean because the old settings were for less air coming in. Also the part about making the car run richer because air takes longer to reach your engine. BS :thumbdown Pressure drop can increase lag since there is more piping the air had to travel threw before it gets to the engine, but it will not make you richer because of that.

Buy a logger and Tune it yourself
If your on the stock injectors there's not much you can tune anyways, just keep the boost under 15psi and you should be fine.

Amen to this post. How do you (maxperformance) know you are running lean. Just because a blinky air/fuel meter tells you? You need to know your timing advance and real ecu o2 voltage before you can make any assumptions about how you are running.

A front mount actually does make your car run leaner. It does this by significantly increasing the amount of air going into the motor, (think, stock sidemount/piping versus new bigger fmic with hard piping and smoother bends), and when you increase the airflow and dont compensate for it with additional fuel, you will indeed run leaner. Your stock injectors are more than likely at max duty cycle.

sickgsx - You got the "A fmic will make your car run leaner" part right, but your logic behind it is all wrong. You say a fmic increase the amount of air going into the motor because of the fmic's hard piping and smoother bends. This is false. If anything, the more piping that a fmic requires is bad, because it causes a higher pressure drop and the air has to travel further (increase spool) before it gets to the motor. The reason the fmic increase air to the motor is because it cools it down more (cooler air is denser, i.e there is more of it in a specific volume).

Um, you want to explain that again?. Frontmount will not affect a/f other than allowing for a cooler and therefore more dense charge.
forget about your a/f gauge, its useless. Pull a plug, the one closest to the timing belt. If its white you're lean.

awdsm - Yes a fmic can affect your a/f ratio greatly. Read my first reply to SpoOLxExO to see why it can affect your a/f ratio.
And pulling a plug to find out if your lean or not. Isn't that finding out too late, after a lean run. Why not have the proper tuning tools (pocketlogger, egt, wideband) so that you can find you are running lean immedatiely and without having to pull over to the side of the road and pull a spark plug.

Yeah, thats a good theory, but it does NOT "Significantly" increase the airflow, because it is the TURBO that makes the air, not the intercooler. Search Effiencey, Pressure drop, then come and chime in...

Yes, your turbo is compressing the air and pumping out a specific psi, but the intercooler can have a big affect on that air before it reaches your engine. If you didn't run an intercooler, then you would just be pumping a lot of hot almost unusable air into the engine. Any intercooler will cool the air, making it more dense, and have a lower intake air charge. You're right that it doesn't increase airflow, but it can "Significantly" increase your performance, horsepower, delaying of heat soak, etc...

The stock intercooler impedes flow, where as a front mount doesnt. Front mounts typically add 25+hp, and all they are doing is adding air.

How and why does the stock intercooler impede flow. If anything, it "flows" better then a fmic. There is less piping involved with the stock smic. Just the lower ic pipe, a small core (great for airflow, poor for efficency), then a short upper ic pipe to the motor. Compare that to my big greddy fmic which has a similar lower ic pipe, then a huge core of which the air is traveling all the way to the driver side headlight, then a long ic pipe all the way from the driver's side headlight back to the stock upper ic location, then through the normal upper ic pipe. That's a lot of piping, and is not great for over-all flow.
Also you say that fmic adds 25+hp. Somewhat true. They won't add 25hp on a t25. But if you were running say a 20g on the stock smic, then switch to a fmic, you will see huge horsepower gains there. You say they are doing this by "adding air". They aren't "adding" anything. They are just taking the current hot compressed air from the turbo, and cooling it down, making it more dense and with less of an intake charge.

That covers most of the wrong advice I found in this thread. Please people, educate yourseleves more before posting, or at least if you're going to talk about something (say a fmic), understand how it work, why it works, and what it does and doesn't do.

 

[SpoOLxExO]

Well, I understand how this information was misposted. But the main point here is, HOW does "Maxperformance" "know" that he's running lean, that is what I first said. Then I got "Sickgsx 316" chiming in about how he only gets 91 octane, and how the B&m modifyer should be his next purchase, blah blah when:

A.Maxperformance is on the EAST coast, so he gets to have real gas.
B.A fuel pressure regulator (Or "Raiser" such as B&M) will not help in any way, when the Stock FPR is Definately being over-run.
C.Its something as easy as a sensor, or boost leak,etc. Point being, back to my first post again...Is that Maxperformance needs to get a logger for a system check, and find out if his sensors are in order.

I would like to BS about how I am a "Intercooler" expert, but I am not. I only own a FMIC, I didn't design it or front like I am an expert. I was only trying to interpolate the fact that sickgsx316 is wayyyy off on his advice and that a simple system check is in order.

Maxperformance, please hold off on buying more stuff that will increase your variables, untill you really know what is going on with your car.

 

[awdsm drft]

How would you recommend he evaluate his running condition other than pulling a plug without ANY logging. If you know another way then by all means tell me.

There is something wrong with your car if you are in fact running lean. You will not run lean at 12lbs simply due to 20-30 degrees cooler intake charge (if that at such low boost). Otherwise I would have blown my motor last winter.

 

[Blk_99gst]

How would you recommend he evaluate his running condition other than pulling a plug without ANY logging. If you know another way then by all means tell me.

I would recommend that he NOT do hard runs with his car, nothing beyond crusing speeds until he does get some type of logging device.

A logging device (pocketlogger at the least) should be purchased if you plan to go beyond basic mods of the car. If all you do is intake and catback, then no, you don't need a logger. But if you upgrade your turbo, fuel pump, fmic, injectors, safc; for any of those items you will need to start monitoring the ecu. If you don't, then you'll be in the position that maxperformance is in and having problems with your car and having no idea what it's doing.

 

[kpt4321]

A FMIC will not change the A/F ratio, unless the denser charge pushes you over the limits of the injectors which you are currently running.

If before and after the install you not over 100% duty cycle, then the AFR will not change with the FMIC.

Yes, you are all correct in saying that the car will be tuned for a lesser airflow and that when you install the FMIC the denser charge may increase the airflow. However, the ECU knows that the aiflow is increasing (thanks MAF!) and therefore it will lengthen the injector pulsewidth which will keep the AFR constant.

If you start out at a very low load (airflow per rev) value and the FMIC increases the load due to the increased air density, the AFR may actually get richer due to the ECU moving up on the fuel table.

 

[kpt4321]

Could you please point out some people who have my 400hp on stock lines and fpr? I do not think its possible.

I know of at least 1 first gen that has run high 10's on the stock fuel lines, which is definatley more than 400 hp.

A local friend of mine runs low 11's with high 120 mph traps all year long, and he dyno'd at ~495 whp. He is on stock fuel lines.

Foot in mouth?

 

[kpt4321]

It seems to me like you are claiming that the only thing that affects air fuel ratio is the turbo and how much boost you are running. I would have to disaggre with you there. Air fuel ratio...stoich is like 14:1 14 molecules of air per 1 molecule of fuel. If you add exhaust, port something, anything that allows the motor breath more freely, you are then dicking with that 14:1 ratio because there is more air going through the system, and in essence running leaner, and need to tune to those mods.

This is all kinds of wrong.

1. The Stoich AFR is actually 14.7:1, and that is the ratio by mass, not by number of molecules. The ratio by number of molecules is much different due to the fact that fuel molecules are quite a bit more massive than the molecules that make up air, a molecule of gasoline weighs about twice as much as a molecule of air (on average, since they both or mixtures of different elements and compounds). That means that by molecular count, the stoich ratio is more like 30:1.

2. The car doesn't run at 14:1 at full throttle.

3. Just because more air is going through the system doesn't mean you are leaner. You are only leaner if you have more air and the SAME OR LESS fuel. The ECU sees the extra air, so it increases the fuel, and the AFR stays the same.

 

[kpt4321]

B.A fuel pressure regulator (Or "Raiser" such as B&M) will not help in any way, when the Stock FPR is Definately being over-run.

Raising the base fuel pressure will make the car run richer all across the board (ignoring the effects of the fuel trims in closed loop).

Maxperformance, please hold off on buying more stuff that will increase your variables, untill you really know what is going on with your car.

Best advice yet!

 

[kpt4321]

Yes, your turbo is compressing the air and pumping out a specific psi, but the intercooler can have a big affect on that air before it reaches your engine. If you didn't run an intercooler, then you would just be pumping a lot of hot almost unusable air into the engine. Any intercooler will cool the air, making it more dense, and have a lower intake air charge. You're right that it doesn't increase airflow, but it can "Significantly" increase your performance, horsepower, delaying of heat soak, etc...

A FMIC can significantly effect airflow.

If the FMIC allow you to have a 50 degree charge temp drop, that can cause approximately 5-10% more airflow, due to a denser charge. 10% more airflow surely is a significant change!

 

[coltboostin]

I know of at least 1 first gen that has run high 10's on the stock fuel lines, which is definatley more than 400 hp.

A local friend of mine runs low 11's with high 120 mph traps all year long, and he dyno'd at ~495 whp. He is on stock fuel lines.

Foot in mouth?

http://www.shearermotorsport.com/

Dan j's car, put down 438whp, stock regulator, I (we) can go on.

Reconsider your thoughts yet?

As for the "flowbench" BS, the intake manifold testing flow bench results showed that the stock manni was the best performer, so :thumbdown to a flowbench.

 

[awdsm drft]

In all of those setups do you honestly think that the fuel pump was ever limiting them?