How do we "properly" calibrate the IAC effective area when making a change to a 90mm TB?
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How do we "properly" calibrate the IAC effective area when making a change to a 90mm TB?
Maybe copy or interpolate the data from a stock tune that has a 90mm? I would think the flow rate shouldn't change too much because IAC effective area has to do with the flow of the idle air circuit at various IAC motor steps not the size of the throttle body. As long as the idle air passage is the same size it should be real close to the 78mm TB data.Quote:
Originally Posted by Redline Motorsports
Sorry to bring this up again, but I have the same question about IAC area with a 90 / 92mm TB. What cars / tunes would have a 90mm TB?Quote:
Originally Posted by Redline Motorsports
I believe all the LS2, LS3 and LS7 engines in Corvettes (2005 thru 2013) have 90mm throttle bodies. Be aware that in 2009 there was a change to the TBs that seemed to affect WOT voltage signals, however. These new ones are identified by having gold or brass colored TB plates instead of silver colored ones.Quote:
Originally Posted by tinindian
Are there any stock vehicles that came with a cable operated 90mm TB? I couldn't find one. They all seem to be ETC (Electronic Throttle Controled) so they don't have an IAC module or passage to use as reference. I just upgraded to a 90 FAST and left IAC Effective alone. Had to tone down the Desired Air and throttle follower to get rid of some hanging idle when hot, but other than that I really didn't have to do much.
For my 92mm NW TB - I did some reading and found I had to map Desired Airflow B4307 vs. ECT and also Desired IAC Airflow (IACDES_B) vs. ECT. If the two tables don't match during warmup you need to offset the entire IAC Effective Area table B4403 up or down, re-flash & map until they do match. It took about 3 tries but I finally got it right - ended up offsetting the table B4403 down about 5 cells. My stock tune had zeros in the top 7 cells (0 thru 12 sq.mm) and now I have zeros in the top 12 cells (0 thru 22 sq.mm). I was amazed how much better the car idled and driveabilty is a little better too. I guess the PCM works better when actual airflow = calculated airflow LOL.Quote:
Originally Posted by Redline Motorsports
IAC effective area does not change on a cable throttle body. You use the same idle air control valve on the 90mm TB that you used on the 78mm TB. It opens the same amount for the IAC counts and allows the same amount of air in no matter the size of the throttle body. What does change is that you can get more air around the throttle body blade because it's larger. It should be all about RAFIG when you are cable-driven.
Actually, after thinking about it, this makes sense. What I have thought was correct may well be incorrect. That calibration must be taking into account some air coming either around the TB blade or the factory hole in the oem TB, so a larger TB with more air coming in around the TB blade would have more idle air entering the intake, so 0 steps on the IAC would be more square mm.Quote:
Originally Posted by tinindian
How about MAF-less tunes? Any alternatives to RAFIG/RAFPN?
i just went for a drive and got a good data log. only surging I'm getting now is when I am going up my drive way off throttle but moving slow. my question is do I copy log then pate and multiply this in my tune or how do I apply the logged values?Attachment 22060Attachment 22061
Paste (i.e. no multiply).
Thanks Joe. I'll try that. It's pretty good driving now but I've learned so much lately ill keep trying things
Good job :cheers:Quote:
Originally Posted by Aint Skeered
I find I'm learning new things about this all the time.
can someone point me to weatrhermans "idle tutorial"? for the life of me i cant find it. (iv seen sspddmons.)
https://forum.efilive.com/showthread...in-single-log)
This is his work. You can start here. There is good info in this thread.
Al
Al, thanks :cheers:
Just want to chime in here and add 2c, hope it helps someone else.
Iv been scratching my head for the last 3 weeks desperately trying to idle tune my 6L with 92mm cable throttle running the LSA TVS 1900 blower with the LS1b pcm. After following the idle tips and tricks tutorial and hacking multiple tunes I still wasn't getting any results. No matter how much I hacked my idle settings mentioned in the tutorial or how many times I performed RAFIG nothing had any direct influence on my idle tune quality and it would stall frequently. That was until I modified my IAC effective area (B4403). If you change your TB or IAC motor from stock nothing seems to work correctly if your IAC effective area is not close. Maybe this is mentioned somewhere but I seemed to have overlooked it.
Great forum, thanks for the info and contributors!
It was mentioned somewhere in this forum, and there also has been talk about it in other tuning forums... but any talk about it has always been somewhat vague. I remember reading comments like "you need to line up all your airflows" and "you need to shift your IAC effective area table", but I can't remember anyone posting an actual method.Quote:
Originally Posted by jeffro
Well this explains why the RAFIG didn't work for me, it spit out lower than stock numbers the last time I tried it. Going to try this once I fix the fire hazard fuel leak. Can someone clarify why effective IAC area matters on a cable throttle when you go up in size? I did bump the 3500 up to an 85mm TB and it idles all over, but I'm pretty sure that's just because I haven't touched the idle from the mishmash crap I dropped in there in the first place. If you put the stock IAC back into any TB is really shouldn't matter, right? I realize the larger blade may flow more at idle, but then again its bypass hole might be smaller too (haven't checked). I can totally understand why a drive by wire car would be affected by this. Or is the effective IAC area only applicable to DBW cars?
The new TB has different cross-section area on its IAC passage...
So you're saying the pintle may seat differently in that passage? I.E. if the passage is smaller the pintle doesn't seat as deeply and thus must open farther to provide the same airflow as a larger hole in which the pintle would seat more deeply? I guess I assumed they'd take that into account when designing a TB for that particular IAC.
The passage 'size' is different, and how the pintle 'seats' is different...
also note that some IAC passages are airflow limited (you have to drill them larger).
Hmm, seems like one could nerd out by simply measuring said passage assuming one had a tool to fit said passage (depending on angles and whatnot). ASSuming the entrance to said passage wasn't also flow limited, right?
You could, and then you would be close, would need just minor tweaking.