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IGNORE. Literally just saw that on the video... LOL.
Hey ChopperDoc,
Would you say that tuning the IAC would come before Idle tuning, or vis versa?
Thanks,
Andy
It comes towards the end because you have to get the RAF table tuned, but to do that, you need to get the VE looking good. The numbers on the IAC table are affected by what the RAF settings are. Once you have good numbers, then tune the IAC, and that is done for cold starts mostly and stability. You will still have to adjust the blade, probably a few times to get the counts right. And the correction does not have to be perfect by the way. You will find day to day it might change a bit. Don't overthink it, once the engine is running pretty well, and counts are good, then you're good to go.
The Base Running Air Flow table is actually the PID "desired airflow" in the scanner. So you can see that would have an affect on the correction. That table comes first.
It comes towards the end because you have to get the RAF table tuned, but to do that, you need to get the VE looking good. The numbers on the IAC table are affected by what the RAF settings are. Once you have good numbers, then tune the IAC, and that is done for cold starts mostly and stability. You will still have to adjust the blade, probably a few times to get the counts right. And the correction does not have to be perfect by the way. You will find day to day it might change a bit. Don't overthink it, once the engine is running pretty well, and counts are good, then you're good to go.
The Base Running Air Flow table is actually the PID "desired airflow" in the scanner. So you can see that would have an affect on the correction. That table comes first.
ahh, I adjusted the IAC table and today did a cold start to log RAF. Desired and dynamic airflow are close, Ill run the IAC again tomorrow morning. That will probably be closer values.
Thanks for the shout out. I saved 1 post in my tutorial as a just in case.....it's now a link to your youtube video
Haha, yeah I saw that. You are very welcome. Your guide was easier to reference than going through the whole procedure lol. Glad you caught that. Thanks for getting at least one of these into a sticky status lol.
chopperdoc I watched your video on idle tunning and made a braf table. I found that it is wanting way more than I have now but my iac counts are good. confused here is my tune and latest scan
chopperdoc I watched your video on idle tunning and made a braf table. I found that it is wanting way more than I have now but my iac counts are good. confused here is my tune and latest scan
So on initial look at the log and tune, I do see your IAC getting down to 0 quite a few times through the log. I'm trying to tell if it's hanging and trying to drive the IAC down to compensate. Spark corrects hanging faster than air will. I see every time the IAC hits the 0 mark, the "desired" is getting down out of reach for the PCM, and STIT's are solidly negative.
It's kind of hard to tell, as there are few spots that it seems like it's idling on it's own. TPS is up and down throughout the log. In your case I would be bumping up the numbers on braf table to match dynamic. The VE looks decent enough to idle pretty well all things considered. The spark tables look a little different, as you have the top set to 45 something degrees across the board. Wondering what the reasoning is here. It does hit this region a few times in the log.
Are you running any type of boost? Noticed you have a 2 bar tune, however highest MAP I saw was in the 80's. Or is this a 2 bar NOS tune with MAP sensor relay/5v "doubler"? Either way, it shouldn't have a huge effect at idle. Remember that spark is the easiest way to correct a hang in any case.
I can dig into it more later, but the IAC could use some work. Try getting the Running Airflow to match dynamic to keep the STIT's happy. The more they try and correct, the more unstable it will get. I would revisit the idle spark tables too. You don't have to make the mains match by the way. Also the actual IAC table is shifted right pretty far. Try plugging in the stock settings on that too, and then fine tune it with my other guide on that instead of shifting the table. Make sure the RAF table is solid before adjusting Effective Area settings.
Most importantly, don't get frustrated, idle tuning sucks, and different setups can be a real headache to get everything to work right.
I might redo my MAF guide to clear up a little confusion using STFT's vs WB as it has occurred to me that some folks don't have the extra "bung" to install the WB AND enable and use closed loop. My bad on that lol. Have someone that is trying to tune using closed loop with an O2 removed. I feel now I have to correct that in the video. I will still cover STFT's since for part throttle areas, but you would do this after tuning with said wideband, tuning everything including WOT, when touching up the STFT's after WB is removed and upon putting the car back in closed loop.
That should would work regardless of extra bung or not. I'll work on that this weekend and clear up the confusion there. Last thing I want is to confuse folks, so I feel this needs to be rearranged a bit.
i should have told u me setup its a 6.2l ls with a vengeance racing kaotic cam, holley highram intake and 102mm throttle body. car has a th350 trans. my car does hang when coming to a stop. my timming is high because I was trying to get timming back up on decal it drops to around 8. your videos are awesome love them. im on a olsd 3 bar tune im going to go turbo over this winter
i should have told u me setup its a 6.2l ls with a vengeance racing kaotic cam, holley highram intake and 102mm throttle body. car has a th350 trans. my car does hang when coming to a stop. my timming is high because I was trying to get timming back up on decal it drops to around 8. your videos are awesome love them. im on a olsd 3 bar tune im going to go turbo over this winter
That's sounds like a mean setup. For your timing, is it undershooting? Not sure I've seen too many drop down to 8 on decel. I would think you'd have some pretty sweet fireballs coming out if it was that low on closed throttle lol.
I see the 3 bar now. I looked just as I woke up this morning, pre-coffee, my mistake there. Didn't scroll down to see the obvious 315 at the bottom. I'll drink more coffee next time before typing. Hopefully I don't mess up this reply, as I am now drinking something else, but not coffee lol.
still getting a hang coming down to idle cant figure this out.
Don't use air to correct a hang, use spark. So in the area it is hanging, note the RPM and Cylinder Airmass (g/cly) from your advance table and remove 3-5 degrees in that spot and smooth. It should settle down much quicker. I normally carry the number a few cells under and to the top of the table and left and right of that spot to make it into a new slope. I cover it in the idle tuning video. If it still hangs, pull a few more degrees out until it returns down to idle properly. Don't go too much either, since then you are setting it up to potentially undershoot. But realistically, even pulling 10 degrees out of the top areas of the table (return cells) won't typically cause this. Every engine is different though, individual results may vary.
1. It gets pretty rich as you tap the throttle, and at one point the RPM even keeps increasing as you let up.
2. The spark tables still look a bit odd with that ridge at the top. I've never seen a need for such a thing personally. The PCM does use adjacent cells to predict in-between areas not on the table. So this can affect cells underneath it.
3. The IAC table limits don't go to 310, and you have the table start very far right of a stock table. However, the IAC appears to be doing it's job. It does seem to open very fast though. I don't shift the table over anymore like that. I use math to adjust it and match it up to the RAF basically. It should be a long slope from 0 - 310. You can try the stock one in there and see if that keeps it from opening so far.
There is probably more, but these things are what I noted. Some work on the VE table in the hang area will also probably help.
Here is the idle spark table from my 98. Not pictured is the "stall saver" here. Normally I run it with the 0 and 400 columns set at 30. This is just one example of many out there, but this thing returns to idle very quickly and has no issue holding idle.
I just watched the MAF tuning video, Great stuff. Are you going to move onto spark tuning? I have learned more from you then any other tuning guides ive seen. Just my style of learning I suppose. Keep it up!
I just watched the MAF tuning video, Great stuff. Are you going to move onto spark tuning? I have learned more from you then any other tuning guides ive seen. Just my style of learning I suppose. Keep it up!
Spark is a touchy thing to tune. It's where you can get yourself in real trouble by trying to push for power. Having said that, yes, I would like to at least cover that, and how to set it up for street tuning, but not for power tuning. For the street, there are a few ways to tune spark using the scanner, though none of them are particularly reliable or consistent. They seem to work best for acceleration and mid range, not WOT. Best bet is and will always be the dyno, followed by the track using trap speed.
I have still yet to push my latest creation up to full potential on spark because I know the risks of doing so without something to measure progress. Most push until they stop making more power, and back off to the last lowest setting. Say if you made the most at 25 for example, and are trying 27, and not seeing more, then 25 becomes the setting. There is no way to know this without a measuring tool like the track or dyno though, which is why most tuners highly discourage tuning spark on the street. Also, for legal and safety purposes as well, which should remain obvious as to why we say don't do it. However, it's not like anyone can stop you if you have a race logger and some visas to Mexico. I'll leave it at that.
06-22-2019, 02:36 AM
