I am on the third try of starting the tune process and am having some idle problems. First time I had a pinched injector wire that was causing an extreme lean situation. Second time I messed with too much of the Idle P/N, in gear, and base tables in the Airflow tab. What resulted was a very high energy when stopping that would push me forward as I was trying to stop.
I have increased my base idle rpm on all tables to 650 from a 525 minimum. I have dropped the cold idle lean factors by 25% in the fuel, open loop tab, on both the park and gear tabs. I have disabled DOD and turned off all engine codes related to this. I have dropped my VVT to 40% (max 10 degrees variance) from factory settings. And finally I have increased the start airflow by 15%. I am currently working on the MAF tuning. The truck starts fine, and the initial idle from 1300 rpm down to 650 runs in the high 14's to the high 16's on the Wideband. Once my engine gets to idle, it runs in the 19 to 21 range and will barely stay idling, or die, if I don't rev the engine constantly. When it warms up, it gets much better but it still runs in the 16-18 range, and is rough. I have only done two tunes on this round and will continue until I find another route. As soon as I press the accelerator pedal when warm, the engine instantly runs in the 14-15 range.
Attached below is the initial pull from the computer, the final setup before my first MAF pull, and the first log file from that run. I am mostly curious about the extreme lean idle, and what I should change. My next thought is to go back into the fuel, open loop tab, and drop all the lean factors by another 50%....
I want to mention, that the last time I ran the tune process on this truck, I had the idle at 700 rpm, and thorough out the full tune it was running very lean at idle. The biggest question I have is the warmup idle. It is in the 20 afr range on my wideband from ambient temp to 200, then it goes to whatever the tune suggests. I am on pull 3 for the MAF tuning and it is idling between 15-16 at running temp on the afr down from 18-19 on the first pull.
You should be targeting 14.7 AFR. Your commanded AFR is 11.63. Go to open loop tables set them to 1. Create a histogram to show you the MAF error and start you tuning process.
I changed my tune file to modify what you have sent for the open loop, and noticed no changes at all.
I do not know where the 11.63 commanded AFR is coming from, this is not on my tune anywhere that I can see, and I don't know if it is the scan tool? I even tried the average of all my AFR commands and it is 11.82 (just playing a hunch)?
Now for the problem, When I went into the Engine/Fuel/General/Stoichiometry, and set all the tabs to 14.7, my engine barely started, and would not run at all. It sputtered, backfired, coughed, and died when I hit the accelerator. I had to go back and reset the commanded to factory for it to run. MY AFR gauge never left the 22.4 range...
On another note, I have gone to the Engine/Fuel/Open Loop tab and changed both the Gas(P/N) and the Gas(Gear) charts to all read 1. I noticed no difference in the cold start, so I changed it back. I also did the same test with the two alcohol tabs, and I believe the IVT Gain Gas tab with no noticeable differences.
I have attached a log i did yesterday, where I started the vehicle, and let it run for about 30 seconds. I then started the scan while the engine was still at about 170 degrees, and ran it until the temp got to 200. Honestly, I started the scan as soon as the engine was running, and the numbers on the MAF table were in the 1000s lean. I don't think this is accurate or even possible, I believe my AFR gauge hadn't fully booted and was throwing the numbers off..... I reset the scan and started again, this is why it was after about 30 seconds.
Lastly, The STFT reset only needs to be done at the end of the tuning process correct? In other words, not every time I drive, but only when I have "finished" the tuning process?
Are you tuning using stft? cause it's not active. There is no stft reset only ltft. I use the LTFT+STFT math to tune the car in close loop. Reset should be done at the beginning of each drive. Did you set all these to 1?Capture1.PNGCapture2.PNG
Did you adjust your MAF curve?
I am currently working on the MAF Curve. I have not completed it yet but it is close. I am tuning using an Innovative brand wide band O2 sensor, and have the Closed loop and fuel trims off.
As far as the tabs in your pictures, I have set them one at a time to all 1s and didn't notice a difference. I dont think I have set them all at the same time to all 1s. When nothing seemed to change, I reverted everything back to factory as to not mess anything up. Should I try making all of them 1s? I had that thought, but I know things can get messed up real quick....
I had already changed my gas and alcohol (P/N) and (gear) tabs to 1, as well as my IVT gain tab all to 1s this morning, and noticed no difference. I have just changed the Air and Airflow gain, as well as Inj temp gain to 1s. I did have my EQ Ratio minimum tab all 1s but I put it back as per your file.
I already tried changing the Fuel/General/Stoich AFR to all 14.7, and it caused a serious problem. The engine sputtered and would not run well at all. When I pressed the accelerator, the engine would cough and die. So currently I have left the Stoich AFR as it was from the factory...
I am about to go drive and check the updated file you sent. I will report the results back...
None of the modifications seem to help. The truck still runs in the 16-20 range on the AFR gauge, and is showing in the 15% lean range on the scan tool while warming up. Again once warm, it starts, runs and drives just fine. Only while it is warming up am I having a problem....
see my last tune file (MAF Step9) I have set all those tabs to a flat 1 already with no noticeable change to the cold starts. I also tried adjusting the stoich tab to all 14.7 and the engine would not run???
I don't want to say too early that I figured it out. I was re reading this post because I thought someone had mentioned it before. Posting a link below that got me on this path:
The reason my commanded fuel was 11.63 is because my FLEX fuel sensor was reading 53% alcohol. On warmup, apparently the flex fuel sensor is testing the fuel and warmup reverts back to the basic MAF and SD tables, especially with closed loop off. So what has been happening is on warmup, my engine has been trying to run on 14.6 pure gas, and then as soon as warm, it switches to 50% alcohol, which is something like 20% more fuel. So I was tuning a flex engine on pure gas (10% or less alcohol), while it thought it was on 50% (which if I understand will make exactly a lean warmup and a rich or stoich normal condition).
Today I turned the Flex fuel off, and instantly the commanded in my scan tool went to 14.6 and The idle consistency, while bad, did not change after warmup. I logged a consistent 20% lean on average on the MAF scale. I now understand what some people were saying about bumping the MAF curve before starting the tune. I added 15% and I think it is already running much better. I will know something tomorrow during the cold start when I leave for work.
From day 1 I thought something was off, because when warm, my engine required very little increase on the MAF and SD scales (this now makes the third time I have started the tuning process). This was because it was already running rich. The cam I added is high on the stage 1 (or possibly low stage 2), and I assumed I would need some significant fueling increases. What I see now is more on par for what I expected....
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