Inferred Ambient ACT

European strategy specific for 2004 ford mustang euro spec but also modified by SVT and used on the 03/04 cobra. Can be used on all 2002-2004 mustang v8 and v6 manual and automatics. Supports automatic 4r70w control. Can be used on 2001-2004 ford F-150 4.6 / 5.4 ecu's if configured correctly as well.
Turbo4V
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Inferred Ambient ACT

Unread post by Turbo4V »

Curious if INFAMB_KAM is still active with KAMRF disabled. I've essentially always left KAMRF off, but I get tremendous heat soak of the ACT sensor after long idles and hot restarts. The ACT sensor is still in the Slot MAF. I see the INFAMB_KAM decrement down slightly lower than ambient as I would expect, while the ACT at times is 60-80 degrees above ambient (hot restarts may show 160+ on 75F day). The fueling goes way lean as a result of false high ACT reporting the air temps far higher than ambient until I get moving to pull in cooler air. Doesn't seem like the inferred ambient is really doing anything to combat false ACT temp readings. Maybe I'm just misunderstanding how the inferred ambient strategy works or what it was designed to do? Does it matter if KAMRF is disabled?
decipha
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Re: Inferred Ambient ACT

Unread post by decipha »

yes it is

why would you leave kamrf off?

inferred ambient temp does not correct the iat its not even remotely related

an act sensor cant read faulty unless the sensor is faulty, theres no such thing as false act temps.

it soubds like you need more startup enrichment
Turbo4V
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Re: Inferred Ambient ACT

Unread post by Turbo4V »

The reason I keep KAMRF disabled is because when at idle for any amount of time leading to high ACT readings (not necessarily true high ambient) the KAMRF will climb up +20-30%. After shutdown and overnight cooling the next restart with true ACT matching ambient, the KAMRF is now driving lambse way rich until enough time passes for KAMRF to update and settle down to something reasonable again.

My opinion is that the ACT sensor is hotter than the air flowing past it during hot restarts for the first couple minutes. If the ACT reading was true then the actual air density would be less than ambient density and the calculated air density would be correct so fueling would be correct. But that isn't what happens. The fueling is dead on when ACT is reasonably close to ambient, but lambse climbs as ACT begins to stray from ambient. If ACT was truely what it was reporting then air density would be less and fueling would be calculated correctly.

I did have to add a lot to the startup enrichment for +200F and above to get it stay running for the first minute after hot restart.
PaulC-turbo5.0
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Re: Inferred Ambient ACT

Unread post by PaulC-turbo5.0 »

Although I dont recall seeing the crazy iat's you are I dealt with similar fueling issues due to heat soak. I re-wrapped my hotside last winter and this time around also wrapped the headers, they were just heat painted previously. That change has seemed to help out alot as my fuel trims didnt move around nearly as much last summer.
red5.0fogger
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Re: Inferred Ambient ACT

Unread post by red5.0fogger »

With the kamrf turned on and idling how does she run? Maybe just let the kams do their thing. The air will be hotter in the piping during a long idle. Maybe it's legit.
Turbo4V
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Re: Inferred Ambient ACT

Unread post by Turbo4V »

The problem with having the KAMRF enabled is once they reach +20-30% during hot idle or right after a hot restart is that the next morning those trims are added during cold start and warmup until the updates pull them back down to near zero. So it is way too rich for several minutes. Fueling is dead on when ACT is in agreement with true ambient air temps.
red5.0fogger
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Re: Inferred Ambient ACT

Unread post by red5.0fogger »

Startup fuel is coolant temp based no? So why would hot kamrf numbers be used on the next days cold start?
Turbo4V
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Re: Inferred Ambient ACT

Unread post by Turbo4V »

Not sure. Good question for Decipha. But my understanding is that whatever KAMRF is already in memory is always going to be added on top of startup enrichment adding that extra % to lambse.
decipha
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Re: Inferred Ambient ACT

Unread post by decipha »

kamrf is a multiplier on airmass which is basically a maf corrector

if the maf is wrong when hot itll be wrong by the same when cold

20-30% means something is wrong

you can set the act max temp to allow adaptives to update. You need to kick that down for now til you figure out whats going on.

If its adding that much fuel when hot idling then your either getting some kind of partial vapor lock from too low of fuel pressure or more likely your injector data is wrong.
Turbo4V
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Re: Inferred Ambient ACT

Unread post by Turbo4V »

Thanks for the suggestion. I will go ahead and try turning adaptives back on and lower the max allowed ACT for update if I can find it.

The MAF error is essential zero when ACT and ambient agree within a few degrees. But once they diverge by more than +10 F degrees or so it sure seems like the MAF error starts walking up proportionally. Fuel injector data is scaled FRPP data for their injectors so it should be correct. It sure seems correct when ACT and ambient are in close agreement.

It could potentially have something to do with vapor lock, but fuel pressure monitor shows normal 44psid and since hot restarts fire right off I don't think it is the root of the matter. Especially since the dead lean condition is persistent for several minutes after hot restart until the ACT comes down somewhere close to ambient.
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