ATS enrichment for heat soak

[Aeroking]

V6 turbo Syclone, FAST classic B2B, air-air, IAT sensor in intake plenum (stock location)

It was really hot yesterday with my FAST for the first time. Ambient was almost 90. When i tuned my truck i left the ATS enrichment table zero across the board, i always let the engine cool down. Yesterday after a drive the truck sat, and the intake heat soaked. IATs stayed around 130-140. The truck idled completely lean, popping and sputtering, FAST WB read 15.9 (max) and my other WB was reading 18.4. I started turning up the ATS enrichment table above 100deg, but it just didnt help. Seemed like the more i turned it up the leaner it got, which doesnt make any sense.

Once the truck was moving fast enough to cool the IATs down, it ran fine again. Seemed like 100deg IAT was the magic number, once they dropped below that it was fine. But above 100deg it went dead lean.

The last i left the ATS enrichment table i was +20% above 140deg, and about +10% at 110deg.

I'll turn it up more if need-be. Is the ATS correction a function of closed loop? My idle/cruise rpms are in open loop, and i dont switch to CL until about 2000rpms.

Any ideas.

 

[norbs]

As far as I have seen the ATS enrichment is a global type of enrichment, so it should be richer everywhere. Since your idling, pw is small and it may need a huge % percentage to see the effect. The speed density calculation is supposed to compensate for this.You should be adjusting afterstart enrichment and decay time so it tapers out after about 1 minute running or so on a heat soak, don't be suprised to see afterstart enrichments in the 30-40% range when hot. The question is what was the coolant temp after the hot soak? I like to have the IAT sensor in the up pipe, try moving it as a test.

Remember:
AFTERSTART REV VS CTS delays the time the afterstart begins after the engine is considered to be running (above 400 rpm usually). You will want to lower this value.
AFTERSTART DECAY VS CTS is the rate at which the afterstart is removed, a higher number here will increase afterstart enrichment time. You will want to raise this value to slow the decay.
AFTERSTART VS CTS is the amount of fuel to add globally based on coolant temp. You will want to increase this value as the collant temps gets past 180 Temp.

It would be nice to have and afterstart table vs AIR TEMP...........though. Add some afterstart, and if that is not working too well try the ATS table next, I really have not seen any tunes where people start modifying the ATS table, but if it helps its worth a try. Usually closed loop idle can compensate for this, and since your in open loop your not getting that compensation.


While you have the ATS table up log AF and PW you should be seeing the changes. If your PW was 1.5ms and you added 50% fuel , your pw would only be 2.25ms for example, so for idle you will need big changes.

 

[norbs]

Here is a nice little write up on heat soak........its not fast related though.

http://m54megasquirt3.blogspot.ca/2012/01/fuel-injector-heat-soak.html

 

[kidglok]

AFTERSTART DECAY VS CTS is the rate at which the afterstart is removed, a higher number here will reduce afterstart enrichment time. You will want to lower this value to slow the decay.

you got this one backwards lol

 

[Aeroking]

The coolant temp holds steady at 160-162 so the engine isnt "overheating". I can try and move the IAT sensor from the plenum to the charge pipe. However, other than ATS correction, and dashboard display, is the IAT input used for any other function? I guess what i am saying, once the intake is heat soaked, what difference does it make to move the sensor, the air is still thinner and the engine should still run lean. Unless the IAT sensor is used in some fuel calculation in the ECU, it should have no affect on the fueling. Right?

I'll see if i can heak soak it again, and check my pulsewidth to see if the ATS corr. is adding a percentage.

Also, as far as the afterstart decay goes, if the decay ends at 1 minute, then it will go back to idling lean because of heat.

I could also trying doing it backwards, and tune the idle with the IATs high, then use the ATS to pull fuel under normal conditions. I dont think it would work well, but i could experiment.

 

[norbs]

Thanks Kidglok, I got up too early this morning, I fixed it up............Anyway its speed density so yes the IAT does do fuel calculations and it is very important. Read that article I posted. After 1 minute or so the engine should stabilize enough to run better, as the fuel will cool the injectors down by then. Air in the intake tube moves faster than air in the plenum, it will cool down the iat faster after a heat soak. If you need more enrichment over time decay it out slower.

 

[Aeroking]

cool

 

[norbs]

Here is a small article on air density vs hp, interesting reading for you
http://www.buildingspeed.org/blog/2012/04/temperature-and-horsepower/...


looks like every 10 degree F change equates to 1% HP difference