i believe sharif or tony from f.i. said optimal is middle or high 12's or low 13's? 14.xx seems too lean?

Correct, at idle it might run in the 14.x area because the system is constantly adjusting, but under load it should really be below 13.0 (not 100% sure on the exact range in 12.x though).

The Stoichiometric (ideal) A/F Ratio is around 14.6, that's the A/F ratio you want to run at idle and little loads (cruising etc..)

It is only that you go rich (12-13) A/F @ WOT because it helps keep the combustion chamber temperatures down which helps in avoiding knock and advancing timing safely

The higher the number the leaner your car is running, hence less fuel and too much air. The lower the number the richer your car is running, hence more fuel.

You will not hurt these cars with a lean condition under 3500-3000 rpm's. You can destroy your engine from detonation in the higher rpm's if your A/F is too lean. This specific car needs to have the A/F between 12:6 - 13:2. In my honest opinion 13:2 can even be a little lean but it is borderline. Yes, in theory the leaner you can make the car, the more power the car should make. However I have found with this car there is a happy medium where it likes to live. That medium is those safe numbers I listed above. Obviously if the car was running PIG rich it would make lass power. For example: if your A/F was in the low 11's to high 10's you would be dumping too much fuel....

Tony

To add one more thing, optimum A/F at idol is 14:7

Well it seems this thread may have answered my question that no one responded to on my own thread.

Seems i threw a lean code P0171, unless this is an 02 issue im wondering if i am indeed running to lean with out a tune. However after clearing the CEL my idle rpm returned to 600 from 1k.

___________________________
Stillen CBE, Gen'3s and Berk HFC

To add another thing, you need to try and take the A/F reading as close to the headers/manifolds as possible. Specifically in front of the cats if you have cats installed on the car. By doing this, you will achieve the most accurate number. Running it in the tailpipe will work but like I said is not ideal.

Tony

Well from reading this: Stillen CBE, Gen'3s and Berk HFC

It is a safe bet to say you are running too lean. Now if this is what caused the code, I cannot guarantee that. If one of the O2 sensors was damaged you would probably throw a different code, so we can rule that one out.

I would say it is time to get your car on a dyno and find out what that A/F is doing. If it is lean, you will need a tune. If you cannot afford a tune then put the stock intakes back on the car for the time being and I bet ten to one your A/F will go back to where it needs to be...

Tony

I will check it again tonight or tomorrow and confirm what my numbers are when stepping on it. Thanks guys.

No, what I meant is that IF your air meter is working properly that even with all the bolt on mods, the car should be able to adjust the fuel so that you do not run lean. In other words, the stock fuel system can keep up with the amount of power you will make with all of those mods. If you relocate or your air meter is NOT reading accurately, you could end up with a lean condition.

I wasn't really talking about the "power" itself rather the power compared to what the ECU can adjust to.

Basically, if you have a G3, you're better off getting the car on the dyno and obtaining your a/f ratios. OR...if you have the software, watch the timing during a pull. If you see timing start to decrease through the run, that means your car is going lean and the ECU is pulling timing to compensate...NOT good!

Nice numbers btw!

When you tune, don't aim for "lean" you will end up with peak numbers, you want the car to allow timing to remain consistent so at times, actually running it "slightly" rich will not give you the peak numbers but it will give you an increase overall.

Of course, don't run it too rich...you want your a/f ratios to be a few points under "lean"
Also, if your car tends to pick up power at any point try actually adding a little fuel in that area instead of leaning it. You'll find that your timing will actually remain consistent VS getting that peak and then having the car pull timing to redline.

so basically once I put my CBE on the car considering i have the G3 and berk HFC i will need a tune immediately?

The "safe" thing to do would be having a dyno with an A/F meter to see where you are at. You can drive the car, but not beat on it too hard until you at least confirm that your air/fuel ratios are within tolerance. That and you could be giving up power by not having it tuned.

Better safe than sorry!

Ahh great thanks! I can afford the tune(aerospace engineer), i was just debating uprev Dyno tune vs Cobb ap or maybee oasis ? just needed to do the research but it seems i may be running out of time. I just hope i havnt done any damage.


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Stillen CBE, Gen 3's and Berk HFC

You have not done any damage, but you are probably just not getting the best gas mileage and all the power you should be, because the system is no running efficiently.

Hopefully you know I wasn't taking a jab at your financial status. I was just stating all of the options. Like Dreamer said, you should be fine just get a tune asap...

Thanks, Tony

Uprev tunes seem to be really good with some of the G's. Like G37Sam for example. Also, in the User CP>>Edit Signature. You can write out your sig there instead of writing it out in ever post :tup:

The tunes really do help bring things in order. MY AFR at idle is 14.6 and when at WOT it drops into the 12s. My MAF readings I took said my stock box with drop ins gobbled up 240 G/S when stepping on it and Im only 8-10 degrees above ambient temps. The tune gav e the car some decent gains and has my AFRs where they should be. Worth the money since you get a diagnostic device too.

Yeah ive just been to lazy to update my profile! Thanks for all the info everyone, ill be contacting uprev this week.

This thread was super informative. I never would have thought some cars with G3 CBE and HFC would have issues with running lean.

So my question is after reading this thread(since I have some levels of ocd)

When I eventually install HFC and CBE on my car, there will be 0 danger of running lean if I stay with the stock intake without a tune? These 2 things would be my only engine mod.

you will be fine without a tune. And if you just do K&N drop ins you will be fine too as that way you wont be changing the size or location of the MAF section and it will still let the car breath better. And if you decide to do a tune, the canned maps will get you some extra gains too.

From what I can tell by looking at the intakes I believe you would be ok with Injen intakes.. the problem with the stillens is that the tubing is too thick where the maf is. The Injen intake is actualy tuned for proper a/f ratios and runs close to stock size tubing where the maf sensor is. I know every car is different but ive always had good results with injen intakes on all my cars. Most of my cars had full catless exhausts and injen intake with no issues what so ever.

Not sure what the thickness of the piping has to do with anything at the MAF location. Its about the diameter of the piping, and that is how some intakes are making the gains they are, is that they make the MAF size a little bigger tricking the ECU on the actual amount of air coming in (more air coming in but the ECU thinks less is coming in cuz the larger pipe means less velocity, if I remember the explanation to me before about this) which then causes the ECU to adjust in a way to make more power.

Zsteve that's exactly what I meant your just being too literal on my word choice. I meant diameter instead of pipe thickness.

Did I just miss...or was there a decision on whether the canned maps nearly match a regular tune for the A/F ratio?

That's right. A larger pipe will have slower airflow than a smaller pipe at a given flow rate. Think of it like a garden hose: when the end is open, a large volume of water slowly pours out. Now you put your finger over it, and all of a sudden the water moves out much faster, but the amount of water coming out is pretty much the same. What you did was in effect make the hose act as if it were smaller.

This concept is important once you know how a maf sensor works. Basically, it's a wire that is heated to a target temperature by an applied voltage (aka "hotwire"). As faster air goes over the wire and cools it down, more voltage is applied to compensate. It is this voltage that the ecu uses to calculate the required amount of fuel.

In a nutshell, it's like this: larger pipe-->slower air-->less cooling of hotwire-->less MAF voltage from ECU-->less fuel injected-->leaner air/fuel mixture.

I think exhaust and HFC's alone have little effect on A/F ratios, as any additional airflow gained by these systems is still going to be metered by the MAF and more fuel will be injected accordingly.



Wow. Sorry, that was boring :icon14:

Ok I am pretty much understanding what goes on now from this thread. But looking at my numbers from a Uprev tune on a 7at w/ Injen CAI, FI CBE and HFC's I feel kind of jipped.:icon14: I also didn't get any of the special valet or anti theft maps. The tuner told me only one map was needed/loaded for my application, and a second would only be necessary if I wanted to run a different fuel. Help me to understand, is this about normal? I understand Mustang Dynoes read lower then the rest. So I'm probably making around 300rwhp?
Also thinking about getting short headers, so I would need to retune it again correct?

Vehicle: 2009 370z
Mods: Exhaust
EMS: UpRev
Base HP/TQ: 272/215
Final HP/TQ: 280/221

http://www.the370z.com/members/neveu...prev-tuned.jpg

Pic is too small bro

Your gains are actually better than what a lot of people, including myself, have been seeing (probably because you don't have that many mods yet, so there's more to be gained from a tune). Whether or not you'll need a re-tune with short headers depends on what they do to your AFR (which is absent from the sheet above). Honestly, I doubt you'll need a re-tune just due to headers. What you want to do ideally is finish getting all your bolt-on mods first, and then do the tune. That way you only pay once. I'm not sure why you think you're making 300whp when your final HP number is 280. You're making 280, not 300. Now, I have no idea which exhaust you have. Depending on which one you have, 280 could be good or mediocre. Which one do you have?

And even if the dyno reads lower I doubt that they would read 20 hp less

Some people barely get over 300 even with intake, exhaust and other bolt ons

He listed he has an Injen CAI, and FI HFC's and CBE in his post. That's making me concerned obviously because I'll have the same mods as him in the next week or two. :/

Edit: Actually I wonder if he dynoed immediately after getting the mods done, because that would definitely skew his numbers. What gear did they do the pull on as well?

Oh, sorry I missed that. I was focused on the part that just said Mods: Exhaust. 280 does seem a little low. But keep in mind that this is a 7AT, which might also come into play.

There isn't that much drivetrain loss on the Auto if any, due to the ratio of the gearing. There are plenty of 7AT's pulling over 300hp+ on similar mods and are basically dead even with the 6 speed.

Keep in mind that some dynos will read very low...

For example... 2theextreme put down 300+ whp on a DynoJet at Altered Atmosphere...

Then with the same mods he couldn't break over 270whp on a Dyno Dynamics at Function Tuned...

so which one is actually accurate

That's open to debate.

I don't think there's a definitive answer to that. It's not like there's some gold standard by which one can compare different makes of dynos against. Like think about clocks. The various atomic clocks around the world serve as the standards by which all other clocks are compared against. Is your watch accurate? Compare it against the atomic clock. There is no equivalent to the atomic clock for dynos. All we can do is disclose what type of dyno our numbers came from when we say our cars made xyz HP/TQ. People in the know will understand the significance of the number in relation to the type of dyno. And those who aren't in the know . . . well . . . screw 'em. ;)

But we all know if you want "signature" numbers you should find a DynoJet somewhere :tup:

Or a DynaPak, if you're just after bragging rights. Of course, when people find out your numbers came from a DynaPak they'll laugh at you. :roflpuke2:

:icon18:

I do need to head up to Altered to get dyno'd... I put down 265.4 on a DynoDynamics with my intakes... I need a bigger number :bowrofl:

I just did a dyno test on a dyno jet

STOCK WITH 1000+ HP

POOOOOOOOOOOOOOOOWER