Fape

[bruce]

Can those corrections really be as a percent of overall AFR?.

2. Has anyone run them on a bench or with a WB to double check what the values really are?.

3. Does anyone account for them in injector size selection?.

4. would almost all the injectors guys normally chose be static at continued WOT.

5. Is anyone changing their values when going to a front mount?

 

[TurboDave]

I've always been told (by folks a lot smarter about these things than I am) that it is a percent of overall AFR.

I choose not to use FAPE (that is to say, I set the table to 1.00) and use the TPS and RPM PE trim tables. They seem to be more manageble, and I don't really spend enough time in PE to worry about much past the 12 second point

 

[TurboJim]

Bruce and Dave,

You both know more than I do without a doubt but FAPE does make big changes. I played with it in my car, accidently too much, and I could barely go up a hill, with it as little as 10%. Car would lay down, puke black smoke etc. I'd haveta let off, let PE clear, then start over, or let off and plant it WOT to make it up a hill. So I haveta assume it makes all calcs, then apply's FAPE.

As for using it in the 1/4, I haveta beg to differ. If it is used for IC soak then it apply's, if it is used as a cooldown, then it applys.

My reasoning, and I've Used it for this is this:
You make a pass. If you watch O2, (lets use it for arguements sake as I know you hate using the NB sensor Bruce) they tend to be a little fat early and lean out as you make your pass. Is it enuf to hurt anything? Probably not, but I've used it and not used it and have gained by using it. I can and will send you a bin I did in Bristol for my pal Rich, I dont think I have a DS file saved before uising FAPE, but suffice to say when I used the PE/RPM trims to keep the car from leaning out at the big end. This hurt spool in his car. Disclaimer: May not happen in all cars as we all know, different cars like different things ANYWAY, I leaned out PE/RPM to where the car pulled at the start, and it'd start leaning out around top of 2nd, or bottom of 3rd. I dunno, 6-7 seconds into the run? I started playing with adding small amounts, I think I wound up at .8 (1.08 or something like that, I'd haveta look to see what the exact value was) to get the the O2's back up to where I wanted them. All this (or this little change, whatever you want to call it) resulted in a run that started at .800 and went ALL THE WAY DOWN THE TRACK at .776 to .779. Totally flat line. That resulted in his best time, and pulled the wheel on his launch. (1.55 60' on ET Streets) I dont think the car ever ran like that before. That chip, with some further playing has gotten down to 11.48 on his last time to the track. As you know, 5500rpm in first may be fine, but 5500 in 3rd might be lean, maybe its Bruces IC saturation theory, I dunno.

So my point is FAPE Can be used as a positive tuning tool. I cant understand how PE/TPS would do anything as you're at 88%-100% all the way down the track, unless you're peddling it. Just gotta be conservative when using it cuz in MY car, a small change made a BIG difference.

Thats my $0.00000002 (probably all its worth)

 

[JDEstill]

Not sure I understand some reasoning here...

If the intercooler is getting heak soaked while running down the track, the air temp going into the intake is getting hotter. Which means the mass air flow is going down for a given boost pressure and rpm.

Since the MAF is presumably pegged, the ecm should be injecting a given amount of fuel based on all those trims, and that won't change as the manifold air temp goes up.

So, same fuel, less air, things should be getting richer on their own without any extra fuel added by this table. Granted, it might get more detonation prone due to the hotter air temps. But why would even more fuel need to be added due to IC heat soak?

John

 

[bruce]

Originally posted by JDEstill
Not sure I understand some reasoning here...

If the intercooler is getting heak soaked while running down the track, the air temp going into the intake is getting hotter. Which means the mass air flow is going down for a given boost pressure and rpm.

Since the MAF is presumably pegged, the ecm should be injecting a given amount of fuel based on all those trims, and that won't change as the manifold air temp goes up.

So, same fuel, less air, things should be getting richer on their own without any extra fuel added by this table. Granted, it might get more detonation prone due to the hotter air temps. But why would even more fuel need to be added due to IC heat soak?

John

But going richer helps to cool the chamber, and prevent detonation. Fuel can also be used as a cooling agent, add fuel watch EGT. Of course wayyy to rich, and afterburning will confuse the EGT.

 

[JDEstill]

Originally posted by bruce

But going richer helps to cool the chamber, and prevent detonation. Fuel can also be used as a cooling agent, add fuel watch EGT. Of course wayyy to rich, and afterburning will confuse the EGT.

Not arguing that Bruce. I'm just saying it will get richer all by itself, without the ecm doing anything extra, due to hotter air temps. So why add even more on top of that? Not saying it isn't a good thing either, just asking the question. How much is too much?

John

 

[ijames]

The FAPE table is one more thing that gets multiplied together to get the final injector pw, so in that sense, yes, you have to take it into account to get the final pw. Fueling is MAF * fuel-air-ratio * inj. const. * (1/rpm) * BLM * INT * battery voltage trim * some other trims including coolant for cold run, and if in pe is * pe-rpm * pe-tps * time-in-pe. The fuel-air-ratio is either the closed loop value (1/14.7 stock) or selected from the FAPE table if in PE (about 1/13.7 stock at 170 deg F). When you change injector size you have to adjust the inj const to get the BLM's back where you want them, and then adjust something else to get the WOT max pw up to 95-100% where you probably want it. Most people seem to leave the FAPE table alone and use the pe-tps and pe-rpm tables to tweak the PW to where they want it. A simple way to start is with the stock chip, and then if say the injectors are 50% bigger than stock, or 30 lb/hr stock at 43 psi * 1.5 = 45 lb/hr, reduce the inj const by 50% and then add 50% to the pe-tps table entries. Then see what the resulting AFR is vs. rpm (usually with the O2 volts), and what the inj pw and duty cycles are, and adjust the pe-rpm table as needed.

Hope that helps.

 

[wilkinshc]

[A simple way to start is with the stock chip, and then if say the injectors are 50% bigger than stock, or 30 lb/hr stock at 43 psi * 1.5 = 45 lb/hr, reduce the inj const by 50% and then add 50% to the pe-tps table entries. Then see what the resulting AFR is vs. rpm (usually with the O2 volts), and what the inj pw and duty cycles are, and adjust the pe-rpm table as needed. ]


Just want to make sure I understand what your saying.


Your saying that if you had 45lb/hr injectors you could leave the injector constant at 30lb/hr and add 50% to the PE vs TPS table entries and then adjust the PE vs RPM table as needed for the O2's, right?

If so seems a lot easier to adjust the injector constant and just adjust the PE vs RPM, but it would show there is different way to get the same results. If you did do it that way would you not have a lean condition when you are not it PE mode?


Thanks
Chuck

 

[TurboJim]

No

He means, as an example, lets say both sets of injectors are identical characteristicly. But one is a 25#, one is a 50#. Lets say the 25# constant is 50h which makes the constant .313. If you put the 50# in there, you 1/2 the constant to make the 50 act like the 25. So in a perfect world, putting ~28h makes a .156 constant and without changing PE trimes, the 50's now act exactly like 25's, and at WOT will only flow what the 25's did. Now, if we add in PE, we get the benefit of a 50# injector.

 

[ijames]

Originally posted by wilkinshc
Just want to make sure I understand what your saying.


Your saying that if you had 45lb/hr injectors you could leave the injector constant at 30lb/hr and add 50% to the PE vs TPS table entries and then adjust the PE vs RPM table as needed for the O2's, right?

Nope, Jim has it exactly right.

 

[mattmor]

great info...

This is great info. But i'm just a little lost. If anyone could expand on this info a little bit. Thanks for the great thread.

Matt Morrison

 

[wilkinshc]

Matt,


I think I understand now, using the Turbo Six Tuner we just adjust the injector flow rate and it puts in the codes for us, but if we were to do it in the hex editor we would have to go into the right line and enter the codes they are say to adjust the flow rate or duty cycle (I think). That would make the 50# flow at the 25# rate and then adjust the PE for the extra fuel. Again with the Turbo Six Tuner is making the changes (we just don't see it).

Right guys?

Thanks Again.
Chuck

 

[Ed Valvo]

I agree with Jim that FAPE does have an effect however it depends how much injector duy cycle there is, especially at WOT. Back in the days before Direct Scan, where the scantools didn't display injector duty, it wasn't uncommon for chip guys to push the injectors way beyond 100%. They just didn't know! During a WOT run, If the injectors are already maxed out, you can't add any more fuel via the chip no matter how much TPS or RPM trim you add. FAPE or no FAPE, can't add more fuel. If the chip was only running 80%, then I can see FAPE working because there is room left.

As for the car leaning out or requiring more fuel further down the track, I would think it has something to do with additional loads our cars see from lack or aerodynamics, additional load in 2nd and 3rd gear vs. 1st, and from the intercooler working more efficiently due to a ram air effect. I doubt the IC's work very well, except as a heat sink, below 35 mph.

 

[mattmor]

Chuck.

I don't think that's the way it works. You've been using the T6Tuner longer than I have. But from what i've seen when you change the injector constant in T6Tuner all that does is convert the decimal value to the correct hex value and place it in the correct spot of the .bin. I've been using hex more than the T6Tuner program because you aren't seeing everything available to you. For quick changes it's great to see the tables in english and be able to input a decimal value and have the conversion done for ya. Anyway that's my understanding of it.

Matt Morrison