I have new to the tuning world, but I have been a mechanic (more on the diesel side) for many years. I am hoping someone can give me a few pointers on my tune I have been playing with. I do have an A/F gauge but do not have it hooked up yet to the log.
I have been doing lots of reading on this site and others trying to get a better understanding of what adjustments to be made. the main use of the truck if for towing, though it is used for a daily as it is a fun truck to drive and gets plenty of looks. I would like to stay with
I did do mid length headers and am running 3 in duals with x pipe to the muffler, and 3.5 out to behind the rear tire. nice part is the truck never had rear O2's to worry about. and I have replaced the injectors with Bosch 4 hole from five 0 performance.
my few areas of concern is that I am getting a stumble on shifting and an occasional KR. there are also a few TPS/MAF positions that seem to have a high fuel correction but areas very close are fine.
Here is an updated log with the HZ channel added. Looks like only one spot where the KR was up much. LTFT at light throttle are showing pulling a lot of fuel. A/F gauge was going from 14.4-15.1 for most of the driving on light throttle.
Fuel trims indicate it needs tuning. If you'd like to begin then load this tune and get a good log like the one you did. Stay out of 100% throttle. It's probably going to run rough on this, but it'll get better as we go.
Be sure to use VCM Scanner>Vehicle Controls & Special Functions>Fuel to clear LTFT and fuel trims after loading the tune and before logging.
Thanks, I will load that one in the morning and get a log. I appreciate the help and am interested in learning the different things to watch for to make the proper adjustments.
here is the log file, it did not run as bad as I had expected with the MAF disabled. I tried to get as many data cells populated on the fuel trim side.
Big change in fuel trims, huh? The first tune had different primary and secondary VE tables. Haven't seen that before.
In SD only secondary is used. In normal mode MAF is used most of the time, and transients are referenced to primary VE based on Dynamic Air Filt. Also, SD is used as a sanity check for MAF. Too much difference triggers P0101.
Anyway I went back and corrected the difference between primary and secondary. Then I used log 1 to make corrections. Let's try this again.
thank you for explaining the VE. that would be my error, I really thought i had read and or saw that the secondary was not used for much of anything on the blackbox and to only worry about the primary.
I was reading through some of your other posts, it looks like you have been doing this for a while. or at least have a pretty good understanding of how everything works, I hope to get there someday. every little bit of extra knowledge helps.
here is the log from the latest update. I had some time before work today so i figured I would go for a drive with very minimal traffic on the road.
forgot to add, currently when I come up to a stop the motor hunts up and down and stalled once, othertimes i was quick enough to give it a little fuel. fun with 3 pedals, lol
here is the updated log. I was doing some compare files on the VE table and seeing some of the changes, starting to understand some of this I think. I am taking it that with smaller number corrections, means that it is getting closer?
There's still a lot of idle hunting. This makes it difficult to accurately adjust VE at low rpm/map. I made some substantial changes to idle characteristics, but the behavior didn't change. Inconsistencies like this make me think of problems elsewhere. When was the last time the throttle body was cleaned? Problem areas are the throttle blade (don't forget backside) and the throat where the blade comes to a close. How varnished is the IAC passage? I don't want to make any changes until that's confirmed. If it's ok I'll try a few things in the tune. Make sure the MAF is clean, too. We're about to head into tuning that.
Throttle blades were cleaned when I had the upper intake off about a month ago, as was the MAF. I didn't pull the IAC, I will do that later today and run a new log to see if that clears up the idle. And also let you know how dirty it was.
And yes the smaller number corrections means it's getting closer. The last tune I used LTFT multiply % half except for the small region in question.
There are all kinds of ways of doing this. The way I do it is by doing a shakeup on the first pass with aggressive corrections. From there I dial it more carefully. That's the explanation for the abrupt change after the first tune. There's probably a fancy term for that method, but I don't know it. It's like action-reaction. Makes sense to me, anyway.
First pass it's usually LTFT % and STFT % half on the fringes. After that it's mostly LTFT % half, but I pay attention to STFT to make sure LTFT is accurate. Where there are large discrepancies I make changes depending on the situation. STFT logging can be adjusted for cell hits. Bringing the number up removes transient effects. If that's not an option I look at the trend of the VE table in that area.
Also, with any of the stages, I smooth between points by hand. I take liberties of interpolating and extrapolating trends based on the way I think the engine should be responding. Usually the adjustment shows correct in the subsequent log. Sometimes not.
It's a numbers thing and a feel thing.
Feel free to ask any questions. It's a good exercise for you, me, and anyone else who happens on this thread. I'll answer to the best of my abilities. I view people who hoard info as not only being insecure but that they have plenty reason to feel insecure.
Looking forward to your findings and the new log.
Last edited by SiriusC1024; 07-11-2023 at 07:24 AM.
I cleaned the IAC and the passage, neither were very dirty. it didn't seem to make much difference. I decided to try and replace it, the second log is with the new, it didn't seem to make any difference either. I also used my scan tool to do a relearn, also no change. after a few seconds the idle does seem to smooth out, but when you first come to a stop it is hunting.
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