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I'm finding a lot of mixed answers in my searches.
I'm fooling around with using a LS7 card type MAF on my gen3 (0411) PCM. The MAF calibration tables are easy enough to log and tune. But I can't find a clear answer on how to get the IAT to read correctly.
At ambient garage temp it seems to read about 14 degrees too high. Not sure if this is linear across the range or not though.
There should be an IAT Sensor cal table under Airflow > General
Quote:
Originally Posted by HackAbuse
I got that, just don't know what what values. From what I've been reading the LS7 table is different increments, so it's not just a matter of copying the values over.
Anyone have a LS3/LS7 file for 3.x I can take a look at? I'm not ready to jump into 4.x yet just to open repository files..
I have an LS7 maf, but my calibration has been modified for the sloppy IAT mod, so it's not accurate.Quote:
Originally Posted by scoob8000
https://ls1tech.com/forums/ls4-perfo...ion-issue.html
Does this chart help at all?
I actually bookmarked that link this morning.Quote:
Originally Posted by HackAbuse
Sloppy mod as in moving iat into the Intake?
I'm pretty sure you can change the scale on the iat cal table.
Nope, using the IAT resistance and a relay to command spark retard for turbo anti-lagQuote:
Originally Posted by scoob8000
You can, but the problem is the newer file column is in ohms. In the older gen 3, it's a percentage.Quote:
Originally Posted by Eaglegoat
I'm almost thinking there's no easy way to do this. Almost need to know the ohm range for the stock gen 3 sender and do some figuring in a spreadsheet.
Try this:Quote:
Originally Posted by scoob8000
http://redshift.homestead.com/Schema...mp_vs_Ohms.jpg
Quote:
Originally Posted by HackAbuse
Well no idea if this will work but here's what I came up with:
The LS7 reads from 284 to -40, took half of 302, used that for my 50% value and interopolated the rest. Gen3 has a max of 284 so I just used that for the first value. I'll have to test this out and see..
EDIT: This isn't gonna work, it totally interopolating blows away the curve. :/
So my idea did not work, interpolating the rest didn't either.
I also found my error percentage at room temp, engine cool and multiplied the whole table by that but still not right. Surely somebody has made it work.
While I am also using a card style MAF with IAT I don't have it hooked up since I will be probably be running SD. I'm using this sensor, https://www.bmotorsports.com/shop/pr...h626c6n0859013
Why not just get a sensor you can use, install somewhere and forget the one in the maf?
Kinda where I was goingQuote:
Originally Posted by kingtal0n
Try these values.....should be close. Based on a 2490 ohm pullup resisitor in PCM....
Ed M
Attachment 81939
Quote:
Originally Posted by mowton
Ed,
You da man! That got me really close.
I used a thermocouple on my fluke in the tube and a hair dryer while logging to test. Tweaked a couple cells by 1-2% and it's dang spot on from 65-140. I'm sure that little bit could be variation from sensor to sensor.
Yea but did you get it's hair dry?Quote:
Originally Posted by scoob8000
Yeah, and then some. :)
So just an update on this:
This mod worked out way better than I could have expected. I've got about 100 miles on it using the IAT built into the maf now.
Maf is in a 3.5" tube with no screen. MAF readings are actually more stable than they were with a stock, ported maf. Even at idle it's usually in one cell. Maybe 1-2 at most. IAT temp drops much faster once you start moving (less heat soak issues).
All in all I spent $11 on the adapter harness (that I had to repin), $32 on the Hitachi MAF, and $28 on the tube.
Glad to hear that helped. I actually found that excel approach several years ago on this forum. Wish I could give credit to the creator (if its yours, let us know). Tweaked some of the math to work with my setup and using excel 6th order polynomial function, developed numbers for LS7, LS3 and even aftermarket units (i.e AEM) that provide their own resistance to temp transform specs to the LS1 percentage approach.Quote:
Originally Posted by scoob8000
The overall accuracy of the equation is somewhat driven by the pullup resistor value and its tolerance in the PCM. I have seen values from 2450 to 2490 ohms. Was the 1-2% too high or too low?
For you excel experts out there, the only thing I can not figure out is how to copy/paste the equation results from excel into the working part of the calculator to develop the LS1 equivalents.....have to type it in.....
Ed M
It was reading a little too warm. But I was also comparing to a thermocouple on my multimeter. Who knows how accurate that is. But we're close enough. :)Quote:
Originally Posted by mowton
I've noticed that too in general with excel and VCM editor. One time it seems like you can copy and paste while keeping formatting, other times it wants to paste the entire row in one cell. (I'm using Openoffice FWIW though).