Correct - assuming you have the right MAF table for the hardware you're running and you've dumped the B0120 threshold to something below normal operation (i.e. 100rpm).Quote:
Originally Posted by TAQuickness
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Correct - assuming you have the right MAF table for the hardware you're running and you've dumped the B0120 threshold to something below normal operation (i.e. 100rpm).Quote:
Originally Posted by TAQuickness
i understand how to do the autove but when you say use the same principles what exactly do you mean?? Can you use one of the MAF maps that efi already has i.e (im not on my comp with the software) so i dont remember exact titles but its something like MAF Configuration BEN LC1 or something like that and log the data with the maf reenabled and log that data and make the correction in the tune and smooth and then be good to go in that area or am i way off par here??
Brian, yes that is correct, you apply the MAF BEN map to the MAF table (using copy-with-labels and paste-multiply-with-labels).
thanks joe just making sure i understood it right
Has anybody found their OE MAF's to be in need of extensive calibration as is? I ask because I at this point of MAF is stock and I'm not really sure if I stand to benefit from MAF adjustments or am I just 'over complicating' things?
Brian,
I think part of your question was missed. Remain in SD when logging B5001.
Joe
By 'MAF table' you are refering to B5001 correct?Quote:
Originally Posted by joecar
Side question, with all this tuning of the MAF I got to thinking and I'd like to confirm what I belive to be correct. As I understand it, If one were to drop the MAF threshold for calc. (B0120) to say 100rpm, you basically force the PCM to use the MAF sensor exclusivley for airflow calculation. Now you can set CL enable (B4205) to a higher than expected limit (say 122*C) and you now for the PCM to operate in OL. At this point I assume two things, first the PCM will derive fueling calculations from B3605 (when not at WOT/PE mode) exclusivley, with actual fuel delivery being influenced by the IFR table of course, and secondly, one could at least theoretically set the EQ modifier for the PE tables to '1.00' (or just disable PE mode altogether) thereby making B3605 the sole source of fueling calculations at all times. No MAP, no VE, no O2 input.
Now i'm not saying this is the 'right' or 'wrong' way to do anything, I'm just trying to get a better grasp on exactly how the PCM logic operates on a basic level.
Quote:
Depends on your method of tuning. Per concept 1, you would use the same principles of the AutoVE tutorial and apply them to the MAF table. Per concept 2 (guys chime in if I misunderstood) you would accept your MAF table as a constant and tweak your IFR table.
But how exactly are you logging the IFR? I read:Quote:
Originally Posted by SSpdDmon
..I'm just not understanding what you are actually logging? When I open a new map in Scantool for example, I use the MANVAC pid as my row, use the BEN LC1 factor as the data but what am I using for the column, and how is the commanded AFR not influencing the final amount of fuel injected? Or should I be setting the same commanded AFR for an entire section of B3605 (say setting all rows 60-80*C ECT at 12.5 AFR) and then driving the car and hitting as many vacuum points as I can and then using the difference in commanded AFR and actual AFR to set the IFR amounts? (Did I just answer my own question? :redface:)Quote:
IFR Table {B4001}: Based on what you believe to be true about your injectors, you should use the IFR spreadsheet RedHardSupra made available on his website (or a similar one) to initially set this table. Then using the reciprical of your BEN factor for your WBO2 along with the MANVAC pid, you'll correct this table. Remember, raising values lean out AFRs and reducing values richen AFRs in this table. This will become an important constant that you will base the rest of your tune on.
Quote:
Originally Posted by jfpilla
You stay in SD when dialing in the maf?? I thought youd dial it in with it reenabled, because in SD its disabled.
dumb guy input....if you were not in SD wouldnt your fuel trims start jacking stuff up vi the 02 sensors
It's not really disabled. The functions that rely on the MAF are disabled. If you look at a SD log you will see the MAF still reports, but without any trim interference.Quote:
Originally Posted by BrianC98Z28
You can calibrate the MAF by way of LTFTs, but it's tedious and old school.
Joecar can probably give a more technical explanation.
I should have mentioned this part is CL.
You're logging your BEN as the data point, MANVAC as indicated in the IFR, and a single RPM column (use label ,8000 - yes use the comma). The difference is, the change you need to make to the IFR table is the inverse of your BEN. In other words, if your BEN for the 45kPa cell in your log is 1.02 (indicating a 2% lean situation), you would apply a 2% reduction to the 45kPa cell in the IFR table. This is because the computer is assuming that the injector needs to stay open 'x' miliseconds based on the flow rate provided when really it needs to stay open a little longer. The way you get the injector to stay open longer is to tell the PCM it flows less. Really, that's what you're trying to fix. If the MAF is saying 'y' grams of airflow per second, the PCM calculates 'z' grams per cylinder of air. Then, it delivers the appropriate amount of fuel. Well, if you're 2% lean, then one of the variables is wrong. If the MAF is flowbench tested and R&D'd out the wazoo like most GM guys will claim, I say change a different variable. In this case, that would be injector flow rate.Quote:
Originally Posted by VTC_WS6
After your IFR has been constructed off your MAF, then you go back and dial in the VE for that IFR table. This is what sets this type of IFR tuning apart from the 2hour 'pro' dyno tune.
The IFR table column is PID-less and unitless, so you can use an already logged PID like RPM.
A calc pid can be made for calculating 1/BEN and this is what is paste-multiplied to the IFR table, as SSpdDmon said (these is no paste-divide-by).
so you're setting IFR from MAF? and how do you determine MAF? fueling calculations using fuel flow and wideband? oh wait, we're back to IFR...
jeff, what was first, the chicken or the egg?
This is an arguement that goes on and on.
I've always been told and read that the MAF is "bench calibrated" but for the injectors it will mate up with. There is nothing sacred about the stock calibration.
Tuning via IFR always ends up with eneven values(curve). I've never seen anything but a straight factory curve.
Suggest that Injectors be flow tested, it's cheap insurance towards a good tune, set the IFR and match the MAF to the injectors.
Just my opinion.
Very cute:mrgreen:Quote:
Originally Posted by redhardsupra
Answer: Neither...theropods came first. If you want to look at it less technically, the egg came first since the chicken evolved to what it is today.Quote:
Originally Posted by redhardsupra
http://www.pbs.org/lifeofbirds/evolution/index.html
;)
As for the MAF method I've been pushing, I still claim it's no more right or wrong than any other method. It's just different...and remember, just because something's different doesn't mean it's deficient. :D Also, I never claimed you would tune yourself to a linear result in the IFR. You can get close though - then find the best line that satisifies most of the cells within a few percent and then tweak with the MAF. End result, a fairly stock looking MAF curve and adhearance to the timing table. Blow the MAF out of proportion and your granularity changes in the timing tables. Plus, with this way you don't max out the MAF by 10,000hz.
Also, I never claimed you would tune yourself to a linear result in the IFR.
My point was the opposite. GM's IFR curve is always linear. I mean to use that point as evidence that the IFR curve should not be anything but linear.
I'm missing your meaning about granularity?
Oh, I must have misunderstood your IFR point.Quote:
Originally Posted by jfpilla
Stock MAF curve tuned, my '01 H/C SS saw ~.76 grams/cyl IIRC. Using the method seen in the tutorial (set IFR, tune VE, tune MAF), I bumped up the frequency so much to get the AFR right that the PCM was now showing .86~.88 grams/cyl. Look at the timing table and see what it does....it shifts everything to the right (i.e. lower timing). Maybe a better analogy would be - it's like stretching an image on your desktop from 600x600 to 800x600. It also means you jump across the cells a little more. In my experience, the more you jump across the timing cells at low RPM, the probability of surging/bucking occuring increases.
both IFR and MAF are smooth functions out of factory. the fact that we must screw at least one of them up to get a decent tune means (to me) that there's a hidden variable (or a dozen).
i'm not saying that one method is better than another either, however, i did say they're all equivalent, and we need a solid starting point. this is my way of arguing chicken vs egg: http://redhardsupra.blogspot.com/200...ss-models.html
I believe part of the hidden variables fall within the injector tables, namely the off-set table, hence the fudgin in the air mass tables.
Given that something has to be fudged, I'm way more comfortable setting up the fuel mass tables to a known constantan and utilizing the air mass tables for fudging due to the higher resolution available in the air mass tables.
BUT, I like Jeff's out of the box thinking and am willing to give it a shot.
Even if a tuning bible were available, we'd each develop our own methods of tuning based on our interpretation of the bible. So long as our methods delivered consistant results, they'd be no better or worse than the next guys.
Monty Python says: SPLITTERS! ;)Quote:
Originally Posted by TAQuickness
on a more serious note tho, i got to work on my ford2gm characteristics spreadsheet last night, i think i'm close to finishing it. it should help out a lot with wacky behaviors from injectors. any testers?
It's likely that many factors are involved. Maybe even mis-matched mods.Like toolargeinjectors. You can get a look at the offset results. These are mine. Stock offset table and stock injectors. It's a WOT run.
I'm game to have a look at it. Both my LC-1's are shot ATM so I'm not so willing to flash any changes to my tune yet.Quote:
Originally Posted by redhardsupra
Since I never purchased the Rental Car Tuning Option (RCTO), I'll have to do the testing on my personal vehicles. I can use any of them because I have purchased the PCTO (Personal Car Tuning Option). I'm particularly curious about the injector offsets because personally, I think they're of relatively minor importance, and involve a number of unknowns which cause a lot of tail chasing. Unless a vehicle is properly instrumented, we don't REALLY know true voltage at the injectors and at the fuel pump, nor do we know actual fuel rail pressure.Quote:
Originally Posted by redhardsupra
so gear up! fuel pressure sensor writeup been done long time ago by TAQ, tested on himself, as well as EFILive's own Tordne, and I think BeerC5 done it too. Voltage at the pump can be easily measured, I'm not sure how different can it be at the injectors themselves.
if you think the injector characteristcs are of minor importance, i'd really like you to experience a perfectly sane STS car that does 9.x AFR on every deceleration, while it's very tame and obidient at any other condition.
I don't think injector characteristics are of minor importance, I think the variance in injector performance is negligible with a 1/2-volt change in voltage (provided you're not at voltage threshold) and with a properly functioning alternator and a battery in reasonably good condition, voltage variations will be transient. If you have to worry about injector performance at less than 12 volts, you have more serious problems to resolve. I'm not trying to discredit anyone, but I'm skeptical about this issue because I've never seen convincing documentation either about the process (hence my remarks about pressure and voltage) or the resulting benefits. We may now have the opportunity to correct that.Quote:
Originally Posted by redhardsupra
Yep...you know I'm willing Marcin.
I however need to get myself a fuel pressure sender so as I can log pressure at the rails as well as I want to replace my reg....as I don't fully trust the one I have.
I logged battery volts versus rpm versus manifold mressure on the drive to work this morning. Most of the log is steady state cruise with a few normal accels and one WOT accel. Voltage varied more than I expected, but lowest was 13.7 volts, highest was 14.3 for a maximum variance of .6 volts. As soon as I get a fuel pressure sensor wired up, I'll move on to the next test stage.
For this part are you supposed to force OL, or stay in CL?Quote:
Originally Posted by SSpdDmon
That assumes you put B0120 down to something low like 100 rpm. And yes, you still force open loop with that method, which means setting op. temps to 14.63 and setting PE where you want it. This simulates closed loop. If you need PE to come on sooner, adjust the PE Enable table by lowering the TP% to nothing greater than 35~40%.Quote:
Originally Posted by azzhauler
by tuning this way, do you leave the VE table alone? just play with injector flow rate is How my car ws tuned by a professional tuner and when I posted it on here last year when I first bought EFI live , everyone told me to start fresh and get away from the injector flow rate tune. I have to say, It worked pretty well as for WOT .
Does Ve Table play a roll still with this method?
This process simply reverses the order of tuning and leaves the MAF curve stock since it should still have it's screen.Quote:
Originally Posted by Aint Skeered
The idea is, drop the B0120 so you're in MAF only mode and tweak the IFR until you end up with an accurate representation of your IFR table. When you're done, it should be fairly linear. If not, there may be other injector tables that are in need of adjustment.
Next, you go speed density like normal (kill the MAF with Fail Frequency). Using your new IFR table, dial in the VE table. Once you're done, you should be able to re-enable the MAF, restore B0120 to stock or there abouts, and not have your fuel trims sky rocket like everyone always does.
Why do it this way? Personally, I'd much rather adjust the handful of IFR cells rather than the 84 MAF cells. Plus, I find it hard to believe that a cam & heads can drastically alter the MAF cal. You put the stock lid and bellow in and you'll still have to adjust the MAF curve with the other way. That to me says something is fishy and something is being fudged. So, fudge the MAF or the IFR??? I say fudge the IFR. Too many other tables rely on what the MAF reports (timing, trans pressures, etc.). That should stay stock IMO. :)
Have you tried this method with an complete aftermarket air intake and LS7 style MAF meter?Quote:
Originally Posted by SSpdDmon
SSpdDmon, let me get this straight: you entire argument about the superiority of the IFR fudging method over others is that it's simpler?
MAF isnt really 84 cells, it's more like 4 parameters describing the polynomial that creates the curve. IFR however is usually a lot more nonlinear than that, as you have voltage dropping affecting fuel pump output (a nonlinear relationship by itself), affecting the rail pressure, and then there's another nonlinear dependency of pressure delta vs IFR... if your argument is purely from simplicity, MAF wins by a long shot.
Only on my LS1s.Quote:
Originally Posted by 405HP_Z06
I beg to differ. With the stock MAF curve, you'll see your voltage drop in your IFR because it won't be linear near 0kPa of manvac. If you have a car with a fresh h/c swap and start it up, it won't idle very well at all. A minor change to the base timing and changing B0120 - it idles right away. If that's not simple, I don't know what is. Trying to adjust 84 MAF cells via BENs vs 16 IFR cells, I pick 16. Also, as mentioned above, think of the effects of changing the MAF curve on things like your timing table. You essentially shift the table to the left by increasing the MAF. Stock curve may show .8 grams/cyl and adjusted curve .88 grams/cyl - you've now pushed the high/low timing lookup to a lesser value. Don't the A4 cars also use MAF readings??? I don't believe a 15~20% change in the MAF curve is right by any means. But, that's my choice to believe that...and I'm not here to dis-credit anything. Just saying this is another approach I took to skin the cat.Quote:
Originally Posted by redhardsupra
$0.02
I like the creativity of SSpdDmon's approach and the fact he has consistent results with this method. I don't know that it will change my ways*, but do think it warrants a comparitive test drive.
* This is largly in part to the MAF not being able to compensate for changes in the induction plumbing. Given the installation environment, the MAF is not nearly as accurate as it is consistent.
SSpdDmon,
I do respect your right to tune as you see fit, so I'm not trying to change your mind, just want to share my observations.
I don't see a voltage drop when I scan WOT into an IPW voltage table.
I like the extra resolution of tuning the MAF and I see other parameters logged showing closer trims. The MAF is really not hard to tune and you need to tune upper frequencies to get WOT PE to match actual. Timing tables are useless and need retuning anyway. A4's use B5919 not the MAF for calculations except for 98's and 99's? If you have an optimal timing table it's used. It seems more fueling dependent tables are affected by IFR changes. I don't find that setting the MAF requires any other changes.
It seems that same injectors in different cars use the same tables?
My engine is an LS7 with longtubes and cold air. It's otherwise stock. The IFR is stock LS7. Seems the right thing to do. The stock MAF table does not work.
Joe
I agree - there's some good resolution to fine tuning the MAF to dial in fuel trims. What I'm trying to avoid is massive changes. I think if you're changing it more than 5% or so, something doesn't seem right. I'm merely suggesting you get the IFR dialed in so, for the most part, commanded=actual. Then, any fine tuning you need to do afterwards shouldn't require anything major.Quote:
Originally Posted by jfpilla
Oh well...I'll keep experimenting. It's fun... :D
No doubt! I'm curious to see the results I can derive utilizing this methodology.Quote:
Originally Posted by SSpdDmon
For someone starting from scratch (bone stock) that is planning a build of any sort, I can see a slight variation of this method providing the means to backcheck/verify calculated injector settings. I seem to recall Geoff @ thunder describing a similar method to derive injector settings.