samgm2

I am using HPTuners to calibrate my MAF sensor.

I have finished tuning my VE table.

I setup another histogram with table: "MAF Airflow vs. Output Frequency"

For the sensor, I am using: "Mass Air Flow".

Is this the right sensor?

Documentation on this site states that I should use "Dynamic Air Flow".

I can't find this sensor. Are they the same?

I am using HP Tuners 2.18

Thanks,

Sam

SSpdDmon

iTrader: (10)

Dynamic Airflow is a PCM calculation - not a sensor. You can either use that or increase the MAF some percentage to add in more fuel (as a safety factor) and use a %Error calculation between commanded and WBO2 AFR to tweak the MAF. How much you increase the MAF from the start depends on what mods have been done.

samgm2

Thanks SSpdDmon.

I just figured it out.

Documentation for HPTuners could really use revamping. So could the layout of the program.

I really appreciate your response.

Sam

SSpdDmon

iTrader: (10)

Np...

marthastewart

iTrader: (1)

What did you do to calibrate the 7000 hz and up? In the normal driving I got that ~1+/-. WOT my MAF is like -14 throught the whole range. I tried to do the special paste for that but it seeme to make it even further off. Any suggestions?

Blades

If you are -14% AFR error at WOT.. then whats your commanded?!! If its say.. ~13.. then your WBO2 AFR is 11.4? The way I do it is if I have -2% and similar values in the adjacent cells I'll multiply the values by say.. .992.. In a perfect world that would bring the AFR error down to 1.2%... However, thats usually not the case.. So... stick with small adjustments like that and don't multiply it by .98.

In your case, you could get away with a 90% reduction in MAF value.. but wtf.. who calibrated your maf to begin with? Post a log file.

LS1curious

Have you ported descreened or otherwise modified your MAF ?

If not leave the MAF calibration alone.

Are you running openloop ? If so you the Openloop Modifier tables RPM vs MAP vs Factor.

Dynamic Airflow is the Ve table. Use that to refine your tip in charecteristics.

Got a big camshaft ? if so if you finally get it to 14.7:1 it most likely be overly rich.

Enjoy.

foff667

iTrader: (2)

if your trying recalibrate the maf sensor you just need to log Mass Air Flow (Hz) since that is what the table in the editor is based on.

SSpdDmon

iTrader: (10)

Yes, this is one theory on tuning. Most of the people on here however don't follow that method. You end up commanding one AFR to achieve another. I'm not saying it's wrong....just a different theory than what is 'preached' around here.

To elaborate some, the problem with tuning that way is that you're tuning based on ECT, not RPM (unless you're running a custom operating system in the PCM). Because RPM is not a factor in that table, your fueling can be off by 10+% for a given MAP pressure (e.g. rich or spot on at 1600rpm, but lean at 4000rpm). By the time you're done fudging everything, it's still going to be off. That's why we try to adjust the VE/MAF tables so that commanded AFR matches observed AFR.

The problem with tuning our way (from some who have dug deep into the source code) is, it is believed the PCM wasn't designed to operate like the stand-alone systems in the aftermarket. The VE is not a true VE, but more of an airflow table. I don't know too many of the details. It's all just part of the never ending debate on how to tune the stock PCM.

LS1curious

Yes i did mean openloop table RPM vs MAp. vs ECT And your tunning for fueling conditions that don;t exist. the obsession with stiochemetry in large camshafted cars is luduadcris. If you achieve it the engine will be so rich it'll fould plugs. Remember Camshaft overlap watse 02 and when you wastes 02 you fool the sensor your using. Ultimately you need a 5gas to ferret out myth from fiction.

Widebands have done alot to hurt the education of people and how they tune cars.

Enjoy.

SSpdDmon

iTrader: (10)

I never said anything about Stoich. All I was talking about was commanded AFR vs. actual. I don't run closed loop for that very reason. Again, I'm not saying you're wrong and I'm right. It's just two different theories. That's all.

LS1curious

The problem you are trying to adress is an illusion.RPM doesn't really change fueling "provided the MAF is in factory condition and ducted as such and the MAF table is correct" and niether does your deviation from fuel vs airflow. What your are really seeing is that overlap cycle shortening down to the point where it no longer genrates large waste oxygen swings. The only change that is really ocurring is that now with RPM going up the Engine is begining to look richer then it did.

for example

2400rpm 40 kpa 16.7:1
3200rpm 40 kpa 13.9:1

Part throttle non pe mode.

the fueling didn't change in the modifier table but what did change was engine speed. the engine was actually 13.9:1 at 2400rpm but due to the overlap cycle length at 2400rpm you saw a much leaner mixture as observed by the wideband.

this is where a 5gas comes into play.

Now when you screw with the MAF you actually screw with the VE table as well. Ve table values are derivied from current MAF Airflow as a function over Time. Thats why you can't assign VE percentages to those VE tables. The back up VE table is the only Real VE table in the system and only come into use during MAF failure.

marthastewart

iTrader: (1)

LS1curious my mods are in my sig. nothing more nothing less.

I honestly have no idea where my maf settings came from. At the 12000 mark its like 539 or something. Since my last post I have dropped that down greatly (mid 300's and which is giving me less of a negitive err number. I know that I am not hitting that much airflow, but since I am hitting 9k-10k hz I like to drop the 12k down and make it a nice curve. I will do a few more runs to try to iron this out. I actually have my err down to -7 ish in the WOT 6000 hz and up so I think I am going in the right direction. Just a lot more special pasting needed!!

Thanks for the input guys, and keep the comments/suggestions coming.

jub jub

I'm not following but I will hang around to see where this is going.

SSpdDmon

iTrader: (10)

What I have observed is the reverse of that (maybe due to limited experience - maybe not) where the AFR is richer down low than it is up top. I don't discount the overlap issue...

You've peaked my interest though and I'm actually going to give your way a go this afternoon. What I don't understand is, since this is all independent of RPM, how do you cure idle issues without touching the VE or MAF tables??? In other words, 2400rpm at 60kPa might be sitting at 15:1, but down around 900rpm at 60kPa it's pig rich. How do you personally tackle a problem like that?

I'm always about learning something new when it comes to this stuff...

BTW, I'm running an SLP MAF w/ a lid of course. I'm assuming I should still leave the MAF table stock?

LS1curious

Generally zeroing out the AFR modifier table for ETC vs KPA helps. And yes I observe that generally speaking its always much leaner at 1500 vs 2600rpm as displayed on the WBo2 then it is in reality. If you car is idling pig rich i would be very surprised. you have to keep in mind fuel smell is not an indication of rich but an indication of waste fuel and 02 from the overlap cycle.

Also don't sweat to much the detials of being lean at high load at low rpm. You still have adjustment in the PE vs rPM table to cover that and you can move the PE enable TPS threshold down to cover those high load areas and use the VE table to bring in throttle delta fueling.

SSpdDmon

iTrader: (10)

So, don't touch the VE or MAF unless absolutely necessary? Or, pull some VE around idle only to get the AFR in line?

LS1curious

Essentially. VE has little influence on Overall fueling. It is only used during Delta trhottle event like slamming the throttle to wot from idle. It is also used as a rationality check against the MAF or during cranking and transient states.

SSpdDmon

iTrader: (10)

Well, I gave it an honest shot last night with several logs/flashes over 3~4 hours. I was able to get the AFR relatively close by using the stock VE, stock MAF and only changing the Open Loop Fueling (ECT vs MAP vs AFR) & PE tables. However, as I indicated earlier, there were significant swings in fueling for a given MAP across various RPMs. And again, the confusing thing to me was it would be fat down low and lean out up top. We're talking mid-to-high 13's around idle, hitting 15:1 around 2400rpm, and leaning out beyond 15.5:1 over 3K (outside of PE). I thought the extra unburnt O2 from the cam's overlap would indicate a lean condition since it's an O2 sensor and not a fuel sensor??? PE I could get close so easily....it was a piece of cake. Besides the huge swings in AFR, the other side effects I noticed right away were sluggishness, idle hunting, and my warm starts went to **** (really bad). I had to pedal it for 30 seconds to get it running and I know my desired idle (base running) airflow is dialed in because once it was running on it's own, the idle trims were +/- 0.2 grams/second. The problem was it was being flooded with fuel...

After that, I threw my OLSD tune back in and it fired right up on it's own, I had no more idle hunting, and the sluggishness seemed to be gone. Also, AFR variance was about 1/2 as much vs. the method I just tried. I'm working on getting that down even more than what it is.

My over all impressions...

Not changing the MAF or VE tables and 'fudging' the commanded AFR or injector flow rates can get you in the ballpark. However, you can only hit a homerun if you're standing next to home plate. Yes, I was able to dial in WOT in a heartbeat. But, tuning to me is the full driving experience (startup, idle, cruise, decel, and WOT). I understand 'pros' working out of a shop who have to tune 5 cars a day don't have the time or the resources to tune the way we do. I'm not asking them to. But, you just can't get the same or better results that you can by taking the extra time to do what we do. Plain and simple...

LS1curious

Sounds like your IFR was way off was it reset to stock values ? Did you have the car in openloop when you tried this experiment?.If not that will cuase all sort of problems in terms of fuel trim correction. the hot start issue was most likely cat lightoff fueling and could have been fixed with the proper Start up decay Air adders. .

What i was trying to explain to you yesterday is that If RPM is going up and the Engine is getting richer at a given MAP reading you have one of 2 culprits.

Cam overlap fooling the 02 sensor
MAF calibration issues and or Ducting Noise.

Did you adjust Idle Airflow values ?
Did you adjust throttle cracker values ?
Did you supplement your Tip In throttle issues by correcting the areas of the VE table where you had Tip in enleanment issues ?

Was the MAf unported and in stock configuration with screens ? If not that alone could very well explain the behaviors you observed.

I am not going to elaborate where the tunning methodology i got came from but its from a source on high.





Generally speaking even the largest of camshafts clean up around 3600rpm or so for a given map value.