jub jub

Not happy with my previous tunes, I put my VE table back to stock and enabled my MAF. I made a few high speed runs and logged DYNAIR vs. MAF frequency. I copied my DYNAIR graph into my MAF table and then I put several hundred miles on the car while logging my LTFT's. I then corrected my VE table by adjusting all the affected cells (positive LTFTs being added and negative being subtracted from the VE table). Since then, my LTFT's have been running +/- 2 for all RPM vs cells. I'm very happy with the results and the car seems to be running well now.

I'm wondering if anyone else has tried this? This method seems to be the opposite of what I've read in the "tuning documents" but the most logical way of tuning a modded engine.

Dixit

iTrader: (1)

Where you lost me is if your MAF was connected the whole time and you made changes to the VE table, it really wont affect anything because when MAF is connected VE is used almost barely used except during throttle transitions and a base to where it should be.

See I was doing this way back when I first got my HPTuners, I was continuously modifying my VE table and never got my LTFTs in line. Then finally one day i started throwing the P0101 error code because I moved the VE table so far out of the MAF numbers that it throws that error based on whats in the max. allowed for error table. Then finally did it the correct way of putting the car in SD mode and getting the VE betwee 0 and -4 and then I re-enabled my MAF and adjusted the MAF table to get it back to the 0 and -4 that I achieved in SD mode.

Dixit

jub jub

I guess I got a typed out of sequence. Actually, when I was tuning for SD I also was loging DYNAIR vs Frequency at the same time. That data is what I used to update my MAF table.

My car seemed to run well in SD mode but my gas mileage suffered. Since I'm still new to this stuff, I'm just trying different things to see what works best.

BTW, I did the same thing you did as far as tuning and it seemed in order to bring the LTFTs back to the point I wasn't throwing a lean code, I had to scale the MAF to a point that seemed disproportional to the original table.

Anyway, I guess I'm just trying to understand what's going on. There's so much conflicting information out there it can be quite confusing to a newb.

Dixit

iTrader: (1)

Got it. The DYNAIR vs Frequency is a good base but still needs to be tweaked if you want it dead accurate because there are lots of values for the same HZ that fall below and above the line, so you gotta try to take an average and then do a best fit line when you are putting the values in there.

With the HPTuners this is really easy now as you can log the MafHz against say LTFT+STFT and wherever you got values that are way off, you can adjust that HZ value and get it back inline with where it needs to be.

When you were in SD totally and logged your LTFT, how was it sitting? When I had it in SD totally it worked great and my Fuel mileage was fairly good.

Steel Chicken

iTrader: (3)

dont forget to turn off power enrichment too, im just learning that PE can screw up your LT's as well.

1) SD tune, w/no MAF, w/no PE
2) rescale maf after SD's are good
3) renable PE
4) WOT tuning (wideband or stock O2 based)

Dixit

iTrader: (1)

Steel Chicken, many say not to turn on PE, theres a debate on that and you gotta look at it from both sides. One is yes it does screw up your LTFTs because when you go in PE you are commanding a different AFR which can definetely screw up your LTFT when logging. However you also need to look at it the other way which is if you disable PE then when you go say 65-75% Throttle you are still commanding 14.7 AFR which is not highly recommended at high rpms or WOT. You will definetely be knocking if you tweaked your Spark tables.

One question I had and wondered, is if you have HPTuners (not sure on EFILive since I never seen it) is why not just on the Histogram put the fuel cell pid in the filter for < 16 ? That would only log the data for LTFT that you want, if you went in PE mode, it wouldnt log those values because you would be outside the filter range. I did this once and seemed to work great, but since I dont know as much as all the other folks on here, dont know what I might have missed in the logging that I shouldve logged.

Dixit

Steel Chicken

iTrader: (3)

I do have HPTuners.

Thats a good point. When you say " set the fuel cell pid in the filter for < 16 " what exactly do you mean? the cells are enabled in a grid...which ones should be ignored? Im just not understanding what it is exactly that needs to be ignored. What does the #16 represent?

jub jub

Right. When I log I stay out of the PE mode and under 4000 rpm.

Dixit

iTrader: (1)

Heres the fuel cell breakdown thanks to Bink.

If you look in HPtuners in the histogram, you can modify the histogram and put filters in the settings. There alot of the stuff in the help on how to do this and what you can or cant do.

Now looking at Bink's information, looks like PE is alot of the cells so filtering it dont really help, but doing a <16 helps to not capture idle information in the histogram if you want to filter that out and work strictly on your VE.

From what I understand any data logged from other fuel cells like 16 and above you are mixing that data with your normal VE cells of 0-15 and then adjusting your VE which is being done with data that is not fully accurate. HPTuners help says you should not be using values from 16+ fuel cells because those changes are temporary by the VCM.

Dixit

Steel Chicken

iTrader: (3)

Dixit, thanks so much. I dont have HPTuners in front of me at the moment, but I think I can figure out how to filter those values now. I do think its the idiling/low cruise thats screwing me up. With acceleration, trims look good, but under idle, easy cruise, they run lean no matter what I do, which suggest O2 sensor problems.

Ill go back to a pre header install flash (which was real good) and try loggin with that filter in place.

ZL1Killa

iTrader: (17)

nothing will be dead on. you will always have your numbers a little percent off. Thats the same way I have tuned my car...still working on getting a more accurate VE dialed in though. The computer (PCM) has built in percent error and changes accordingly to things going on....the computer knows what its doing. Do the SD tune and make sure cat protect is off and tune your PE table according to what you want and you are set. scale injector table up if you changed injectors and you are good

Steel Chicken

iTrader: (3)

ZL1Killa the problem is ive done that before, and it worked good. Whats happening now is at idle/cruise conditions, its constantly reading lean. I have values in my VE table over 100! I adjust, retrim, and it keeps want to add more and more. I dont mind them going back and forth, but they keep going more and more lean.

Dixit

iTrader: (1)

Wait are you saying you got values of over 100 on idle cells?

jimmyblue

iTrader: (11)

It's possible to have VE over 100 (say, if you're
"on the pipe" and getting both great scavenging
and some resonant peaking on the intake side as
well).

But otherwise VE>100 probably indicates some
other aspect is reporting air short or fuel long.

No way would idle or low cruise be 100% VE, but
near torque peak, it could happen. Torque peak
and VE peak ought to coincide.

Steel_Chicken, don't chase VE in closed loop until
you have O2s that give realistic results. That, not
the actual airflow metering, is the source of the
trimming drift; no amount of enrichment will make
sleeping O2 sensor read right.

Steel Chicken

iTrader: (3)

OK well I took out during lunch break and did some testing. Heres what I found. I went back to a known good pre header install tune.

In Speed Density mode (maf fail frequency = 0) , everything is fine. ALL trims are < +-5. No cold O2 sensor problems either, they started working almost immediately after I started her up. ECT =~ 100F

as soon as enabled the MAF and reflashed, all my LT's immediately started showing -10 or greater in almost every cell. This happened whether I had PE disabled or not. So, could the MAF effect LTrims? I know I need to remap the MAF, but could a stock MAF config be that screwed up with just LT's and a CAI?

By the way guys, I really appreciate your input, ive learned so much from this forum.

jub jub

That's strange. When I reconnected the MAF after SD tuning all my trims went +25!

Steel Chicken

iTrader: (3)

my bad, I got the -/+'s messed up. when I enable the MAF, it says is running lean, so the LT goto +10 or higher. Why would the MAF effect trims though?

jub jub

Greater volumetric efficiency means you should be seeing a greater charge of air with corresponding fuel. The PCM looks at the incoming air in the way of MAF frequency and see's that it's basically the same as stock, so it injects a given amount of fuel to correspond. Of course the O2 sensor's have a say in all this and report a lean condition based on their input and other parameters so you wind up being lean, thus positve trims.

I think that's right.

Steel Chicken

iTrader: (3)

That kinda sounds right. What I dont get is why it wants to "run away" with the trims. It can say all the cells are about 10 points too lean, so I richen the VE table, flash, run again, and 10 minutes later they are all 10 lean again. After doing this 3 times I decided something else was up. At this point im just gonna recalibrate the MAF, based upon a known good SD tune. I haven't done this yet and am looking forward to figuring it out.

Theres no feeling quite like the joy of discovery...AH HA!

jub jub

Your basically seeing the same thing I was. It seems I was always having to adjust up! I was like WTF? So I ventured on a journey of my own and just started experimenting with different things and I think at this point, I have a pretty good tune! When I log data now, my calculated air intake and the MAF correspond to each other and the trims are remaining relatively flat. I guess I can't ask for no better than that.