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IAT "anti-lag" switch, looking for pointers, HPTuners user.
So I'm trying to build boost before I put a bunch of heat into the tranny.
One idea I came across was to use a momentary off button in line with the IAT sensor. Hit the button and the PC "sees" -38*F
Then you go into that -38*F IAT cell and pull timing (it also appears to dump fuel even though I have disabled the "complex fueling model that combines IAT and ECT for fueling)
So far I'm having limited success.
#1 the tires spin before I get over 101kPa ...so I'm gonna try the sloppy 3rd gear mod
#2 the IAT spark table does not have cells for -38*F...I fudged it and pulled 10* and 8* from the lowest two rows as seen here
while it does seem to build boost a little earlier, (am i reading it right? is it igniting at 10* btdc ?) there's clearly no spike in the drive pressure that would make me think any ignition is happening with the Ex. valve open
any ideas on how spool faster (without header wrap---i loathe fiberglass spinters) are mucho appreciado.
You also have to open the multiplier table and make sure you enter a 1 into the same columns that you are using to pull timing.
The timing is an addition table. So if you have 25 degrees at 105 kpa at that RPM and you have a -10 in the column, it will drop you to 15 degrees. for fast spool, you need to make sure you have less than 10 degrees overall timing. You can pull up to 25 degrees with IAT correction table.
aight we've passed the point where my knowledge ends.
All i'm seeing in the main spark table is airmass in grams. is there a way to convert that to kPa?
Also there are two multiplier tables for IAT, I assume the first multiplier is the one you're referring to since the second is for ( i think) the "complex model" which uses ECT and IAT to correct spark. (i have that disabled while I play with the anti lag)
It looks like your biggest problem is the fact that its dumping fuel. You really need to fix the AFR correction for those temps, it will spool much easier.
The multiplier table multiplies the values in the IAT correction table. I typically set the table how I want it and either use a 0 to disable IAT changes for that RPM or a 1 to enable what I have in the table.
With the IAT anti-lag, I can build 3-4 PSI in neutral. If I have it pull 25 degrees and make it go bang bang, it will usually build up 8 PSI or so in neutral. When I use the third gear sloppy T-brake, I don't have to pull any timing at all with the IAT anti-lag and it will still build 10 PSI by 3000 RPM. This may all end up becoming irrelevant if you do the sloppy Tbrake.
for the AFR at those temps I make my changes in the Fuel>open & closed loop> Open Loop>eq ratio table right? under 14* F degrees they were at 1.3, and I switched them to 1.
my spark correction table for AFR is already zeroed
I did play with the sloppy brake yesterday and it works awesome. It still puts a bunch of heat into the tranny though, I was hoping I could make the IAT trick work to avoid that.
I also would like to figure this out for a manual trans car I am building up soon.
Just use a 5-pin relay. Cut IAT signal wire and put one end on pin 30, other end on 87A (normally closed). When you give power to the relay, it will cut signal from IAT to ECU and the ECU will read IATs as below 0. You can wire up this same relay to the nitrous relay and it will happen automatically when nitrous is activated.
Sloppy T-brake works similar. You ground the wire going to the 2-3 shift solenoid, forcing trans into 3rd gear.
I think this all works a bit differently for each setup.
I assume you are on a two step?
I did all the timing settings in the main timing table.
I start with high timing at my two step rpm at 100kpa.
then ramp the timing down as it builds boost. I end up at 13 degrees and by this time my foot is on the floor.
It makes 10psi this way. Takes about 3 seconds total to get there.
To to figure out where I'm at in the timing table under boost I created a graph of Timing vs RPM vs MAP.
then compare it to your Cyl Air values in your log.
CylAir hits 1.2g/sec (the PCM limit) at about 6 psi.
Lastly, this all works best if you have good rear brakes.
since you essentially have a trans brake with your 4L80, that eliminates the rear brake requirement.
i just wanted a foot brake car. And have a TH400
The two step will help immensely. Night and day.
I don't have a working trans temp gauge.
I'm only on the two step for a few seconds, so it's not something I worry about. Never burnt the fluid.
add a nice boost controller with overboost protection and im halfway to a gold box
Yep.
I went with the stock ECU before Megashift trans control was a thing.
That played a big part on my build, otherwise I would have built a fuel system to handle E85 and ran a full flex-fuel based setup and skipped out on the 2-step box. I've learned how to make it all work, though.
I recently figured out how to do boost by gear on the stock ECU with an 80e, and its been working great.
I went with the stock ECU before Megashift trans control was a thing.
That played a big part on my build, otherwise I would have built a fuel system to handle E85 and ran a full flex-fuel based setup and skipped out on the 2-step box. I've learned how to make it all work, though.
I recently figured out how to do boost by gear on the stock ECU with an 80e, and its been working great.
When I get it tested more Ill post the results in detail.
Works great on the street though. No more black lines from a 50 roll on ET pros.
Third gear sloppy brake and a 2 step does have its downsides at the track. Theyre both on same button. Unfortunately the 2 step deactivates instantly, and the trans takes as much as a full second to downshift back to first gear, so 2 step has to be set about 600 RPM low to anticipate rise in RPM and boost.
bump. I am looking to do something similar on my 2000 C5, retard timing when the IAT goes to 14F, which is the lowest temp available on the table "IAT Spark Advance Correction".
I want to do it a bit differently and try to use the clutch to trigger the IAT cut using a relay - anyone ever done that before? (This would be used in conjunction with the No Lift Shift setting of an N2MB Wot box)
11-06-2016, 03:12 PM
IAT "anti-lag" switch, looking for pointers, HPTuners user. 
