MAF Tuning Help.

[55Belair]

Using the videos posted here by ChopperDoc, I'm slowly getting through getting this thing tuned.

I've adjusted the MAF Calibration with data from 2 separate logs and still find the log rich. Am I missing something? Should PE be turned off when tuning the MAF?

I've attached my Tune and Log files. Thanks in advance for any info you can provide.

[5FDP]

PE can stay on. The error % doesn't matter if it's running at stoich or PE, it's always showing the error between the command vs actual.

Even though you had it in open loop with fuel trims off the long term fuel trims were still doing something in that log because the trims perhaps were not cleared with the VCM scanner prior to data logging. It's not a lot but the negative LTFT were still active because it wasn't cleared. It should read 0.0 all the time if everything is off and cleared.

Don't make us sound like a broken record with those injectors man, it's like being held wide open with 110% duty cycle and you can't really control it there.

[55Belair]

the trims perhaps were not cleared with the VCM scanner prior to data logging. - Yup, you nailed it, my bad. How do I clear them in scanner?

Don't make us sound like a broken record with those injectors man, it's like being held wide open with 110% duty cycle and you can't really control it there. Sorry guy, you lost me.

If you are talking about my IDC being maxed out, I'm doing my homework on what injectors I need. Was walking through the bone yard today and not a flex fuel vehicle to be found. I'm now looking at a new set of 8.1 L injectors. Right now I don't have a clue as to what is required to swap to bigger injectors but I'm trying to educate myself.

[ChopperDoc]

Clear the stored LTFT's with the special controls in the scanner. Before you start the car or log, connect the scanner and use this button here (pic at the bottom). Find "LTFT's" and clear them. Lots of really sweet features under this function if you haven't played with it yet. Hope the rest of it is going well for you. And yeah, don't disable PE. It only changes the "commanded" number, and the table you should of made will reflect the error from that vs actual AFR.

You don't want to be running lean with PE off or something, as that's a great way to break stuff or destroy parts like plugs and pistons. Detonation is no joke under WOT. Do not turn off PE. I don't even think I mention it at all in the MAF guide, since it's supposed to be a follow on to the VE guide, which is where we set the PE numbers and I explained how to activate it/adjust it. I know for a fact I never said to turn it off though... If it's rich, adjust the MAF table accordingly. Don't change the commanded. Bring the airflow up or down to match commanded. Hopefully that makes sense.

Here's the button in the scanner where you clear the LTFT's... Also, every time you write the car, it should be clearing out any stored memory like that, but never a bad idea to just clear them anyway. It takes like 2 seconds. LTFT's should also be disabled in the tune, as well as STFT's. Just use the WB to dial it in, and if later you want to match the cruise areas to your O2's then go ahead tweak the table using STFT's in those areas. That's completely optional though.

Controls and Special Functions.PNG

[ChopperDoc]

What transform are you using for your WB? Can you post the formula?

Tune setup looks good. You seem to be getting this thing together though. It's not a quick easy thing to learn by any means. Also, since MAF is back on, you can return the values on your low octane table to the lower settings, as a backup safety. I'm going to cover how to tune spark eventually, but it's much more complicated to explain than the MAF or VE. Essentially, I cannot necessarily make a "guide" on spark tuning, because it's special to each car. There's no real stone set method, but rules rather, and theory. It's a weeee bit more complicated to explain lol.

Last thing I want to do though is have guys get it wrong and mess up their engines. Stock settings usually won't get you in too much trouble while doing the other tables, so I don't really cover it. But if I know guys, we like to make stuff faster, and spark is what does that, to a point. It's also what causes detonation and can cause engine damage too though. You can see why I am slightly weary of doing a guide on it lol.

[55Belair]

Thanks for the reply, very helpful in moving my education along on all this stuff. My WB is on the fritz again, the Bosch sensors keep crapping out I've gone through 2 since May. I was hoping to get this all dialed in before the car goes into storage at the end of the month. I've ordered another just now.



What transform are you using for your WB? Can you post the formula?

Not sure which formulae you are looking for here. Could it be the formula I use to convert 5V WB signal into useable info in scanner?

[ChopperDoc]

Yep, that's the one I'm asking about. Because different sensors have different offsets and so on. I have a few already stored in my maths list, from other folks, but they all vary a little. Was just trying to see which one you are using so I can see what your AFR is really doing.

[55Belair]

I'm using the EGR channel to bring in the WB signal and the WB and scanner were very close so here is my formula:

([2811.10]/.5)+9.9

[ChopperDoc]

Thanks man. I'll have a look at it tomorrow. Hopefully you got your issue sorted out

[RicksPerf]

Regarding LTFT car was running nice but LTFT was maxed out at +25 . i am going to tune maf but should i add some fuel to the ve map now that I have cleared the LTFT's ? I have O2s disabled and also DFCO Worried about WOT pull being lean Thanks for any input . Just getting into HP tuners..

Gen 3 . 5.3 Silverado

[5FDP]

If the LTFT was that whacked and the engine was stock, that would be a problem. Figure something like low fuel pressure or a bad intake/vacuum leak. Or exhaust leak pre o2 sensor.

If the engine is modded with different parts installed, those first two things should be verified first. Making sure you aren't low of fuel pressure, making sure you have no vacuum leaks. Then it's making sure injector data is correct if you changed those. Having no exhaust leaks as well.

After all that, then you could do a test and adding in say 5-10% worth of fuel to the MAF/VE to see if the fuel trims come down. Or go straight to wideband tuning. Wide open throttle should be the last thing on your mind, getting idle and part/medium throttle done first is what you want. Then it would be easy to transition into full throttle because if you saw the wideband spike lean you could let off before you hurt something. From there doing a quick and dirty fuel change to the MAF/VE would be easy. Find where it's going lean and add 10%, go at it again and start logging your data to fine tune it.

[55Belair]

You should probably start your own thread - you will get quicker answers to your questions and won't detract this thread!

[ChopperDoc]

Here brother, plug this back into your maths parameters to turn your raw AFR into a % error from commanded.

English version:

100 * (((EGR / 0.5) +9.9) - AFR Commanded) / AFR Commanded

Scanner actual:

100 * ((([2811.10]/.5)+9.9) - [50121]) / [50121]

Then plot that on your MAF freq to get the appropriate corrections.

[55Belair]

Thanks for the help, this is much appreciated.

Can you share how this differs from what I was doing?
I like to try and follow along.

I have to wait until my 3rd replacement WB sensor gets delivered for me to put this into application, hope I can do this before the car has to go into storage.

[ChopperDoc]

I'm not completely positive what you were doing before, but if you were just logging the raw AFR numbers, it's much more time consuming to dial everything in. That formula does all the work for you and tells you what the % error is instead of the raw number.

If you had a PRO version, logging the WB on that basically does this for you with the "AFR error" PID. Since the PCM has no idea your EGR isn't actually an EGR, and neither does HPT for that matter, you have to do it manually. It's the same math from the predefined list under maths, except for the AFR sensor is replaced with your EGR channel and transform.

[55Belair]

Everything I know about tuning, I learned from your videos. LOL!

I posted the wrong formula, here is the one I was using:

100*((([2811.10]/.5)+9.9)-[6001])/[6001])

Sorry about that, I got confused there for a minute. The one I posted earlier is the one I was using to display AFR from the wideband, I see you are using the sensor while I am using Air Fuel Commanded not sure what the difference is.

Instead of using 50121 should I not be using my WB math parameter (in my case WB AFR which is 61002) ?

[ChopperDoc]

No, you can use that one too. The formula you have up works fine. I was just making sure you were converting it, as the formula you gave me was just the raw transform. I didn't know if that was all you were using. I'm thinking about doing a quick guide for folks out there like yourself who aren't using the PRO version, and thus have to tackle getting the signal into the scanner in other means, like EGR or AC pressure sensor. Don't think there are any videos out there that cover that.

[55Belair]

I found and used this one when I was trying to bring my WB signal into my scanner:

https://www.youtube.com/watch?v=Ru_2M2uGSKs

[ChopperDoc]

Yeah I found that as I started looking for one lol. I think it can be improved a little, adding in more detail on the transforms, and laying out the formulas. It leaves a little to interpretation as is. Still a good video though.

I really want to do one eventually to cover all the crazy possibilities for math in the scanner. There are so many possibilities, and some very useful little tricks to plug in. I use the custom PID's for all kinds of things. I make it work for me. Surprised the scanner hasn't asked me for a raise or a promotion lol.

[55Belair]

Agreed. Having all the videos in one place would be a great. I'm surprised your video thread hasn't been made into a sticky yet. They would certainly answer many newbie questions like the ones I had.