Quick question(s) on STFT

[Cory S]

And yes, I'm beginning to think high IAT isn't the end of the world.

Ever since Ford put viewable IAT on the gauges, people have lost their minds over IAT’s....it’s ridiculous. Especially on an N/A application. If the DA of ambient air is nasty, there’s nothing you can do. Lowering IAT a few degrees doesn’t add more oxygen since the incoming air charge is not under pressure. Turbos however, will fill the volume in the plenum when IAT’s are lower and make up for lost oxygen volume.

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[shogun32]

Ever since Ford put viewable IAT on the gauges, people have lost their minds over IAT’s....it’s ridiculous.

hey now, I gots to get every HP out of the engine I was promised by Ford marketing. Because my weenie is small and winning the 300ft race from light to light is the only meaning I can find in my otherwise empty and pointless life.

 

[Brian@BMVK]

ONLY thing I did was open up the grill.

Just for the air inlet or the whole grille? Also with opening it, do you have something like the big mouth there?

 

[GregO]

I'll put the gen 2 PMAS heat shield back on, without sealing it to anything. Just to see if the wash is really the culprit here.

This is going to be interesting.

 

[WildHorse]

Just for the air inlet or the whole grille? Also with opening it, do you have something like the big mouth there?

Just the air inlet. Yeah there's something similar to the big mouth.

 

[WildHorse]

This is going to be interesting.

When it stops raining.. I think a lotta people are gonna get some feelings hurt. Myself included haha.

 

[WildHorse]

Want the bad news or the good ?

 

[K4fxd]

Spit it out

 

[WildHorse]

Spit it out

Using anything to seal up the PMAS will make the MAF wig out while at steady cruise. Not controlling airflow into that whole area will make the MAF wig out at steady cruise. So hence, my fluctuating fuel trims.

With gen 2 PMAS shield 'as is'. No extra sealing. Good to go.

So expect higher IAT, however I'm now convinced it's no big deal until it gets stupid high.
Logs showed the PCM didn't give a shit, so neither do I.

Trying for a year to manage IAT was a COMPLETE waste of time on my part. That I'm sure of.
Cheers.

 

[btcarmd]

Guess I could. I need to purchase one of those testers though.

You can use an empty water bottle. Just mark 11 equally spaced marks, fill to the first mark with water and the other 10 with suspect fuel. Shake up and let sit for a couple minutes. Water will mix with ethanol and level will raise to indicate % of ethanol.

 

[WildHorse]

You can use an empty water bottle. Just mark 11 equally spaced marks, fill to the first mark with water and the other 10 with suspect fuel. Shake up and let sit for a couple minutes. Water will mix with ethanol and level will raise to indicate % of ethanol.

That is a great idea ! Thanks !

 

[GregO]

Using anything to seal up the PMAS will make the MAF wig out while at steady cruise.

Good stuff !!!
I’ll assume with the PMAS Gen 2 heat shield you kept the grille opening the same ?

 

[WildHorse]

’ll assume with the PMAS Gen 2 heat shield you kept the grille opening the same ?

Correct Sir.

 

[markmurfie]

Why would my STFT around 12-14% ? Second question : Ideal WOT AFR should be around the mid 12's. Why would it be mid to high 11's ? I'm thinking this is related to my first comment. No pending or CEL. Thanks.

What are your LTFTs at when your STFT are 12-14%, maybe they haven't had enough time to learn that KAM cell yet, or unlearn something which can usually be sped up with a reflash. The STFT are an immediate reaction correction to what the O2 sensors report. There has to be a few combustion events with incorrect AFR that happen before this correction can be sensed and made. LTFT is learned to make it not have to react, just do the correct fueling right away. Hence LTFTs job is to keep STFT with in +/- 1-2%. Its slow and takes time to learn what that correction is.
the default cells are something like 0-.5lb/min, .5-2lb/min, 2-4.5lb/min,4.5-7.5lb/min,7.5-15lb/min,15-20lb/min,20+lb/min. To learn you would need to hit and hold an airflow in the range and hold it steady for up to a couple minutes if there's a lot of error to learn. in cells like 15 lb/min and up thats basically WOT. At ~5-10 second per WOT pull. That is about 6-12 WOT pulls if there's a lot of error. The goal/ benefit to tuning is to reduce the error so that it learns the error in 0-2 times the KAM cell is hit.

The ideal WOT AFR is subjective because of a specifics fuel being used proneness to detonation. There's a power plateau between .82 lambda and .88 lambda, where anywhere on it will make an insignificant difference in power output. It can make a big difference in detonation limited spark advance. In can also make a big difference in fuel consumption and tail pipe emissions if you care about those.

14.08*.88= 12.4

14.08*.82= 11.5

 

[WildHorse]

What are your LTFTs at when your STFT are 12-14%, maybe they haven't had enough time to learn that KAM cell yet, or unlearn something which can usually be sped up with a reflash.

I'll have to check my logs. Same tune since April and over 1000 miles. My targeted lambda is .83 at WOT.

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