WOT - runs rich at high RPM range

[metroplex]

On the SHO, I noticed that the wideband data shows I'm running rich at around 5500-6000+ RPM at WOT. Commanded lambda is 0.85 at WOT, and the actual lambda is 0.85 up until that region, which it then dips down to 0.78-0.79

I'm running about 17-18 psi

I looked at every table and made all of the changes (COT, min lambda, etc...) and changed it all to 0.85, but it still dips into 0.8-0.81

Is there a table missing? Fuel source still shows (OL) Power Enrichment during WOT testing, and no limiters are showing up. Other than a missing table or a setting I missed, does this seem like something that needs to be adjusted with speed density?

[murfie]

I read your tuning guides. Very good and thank you for sharing.

In them you mentioned not knowing what the exhaust temp table does in the COT, Lean cruise section. This table is the inferred exhaust component temperatures. It is based on load and RPM. You mentioned your cats not getting more than 1500*. If that is so you can lower values of this table and prevent any exhaust over temp control based on the inferred temp values. Flange and O2 sens temp control could have missing lambda value tables causing this rich condition.

[metroplex]

Wouldn't the lambda values for the exhaust flange/O2/cats kick in only when the temperatures were deemed too hot? The lambda goes from 0.85 to 0.80 when the cats are about 900F, hardly close to the exhaust temps in the table (1800+). I don't believe there are PIDs for O2 sensor temp or flange temp.

I'll have to look at some of the other tunes in the repository, and even fire up SCT's Advantage to see if Ford generally has lambda values for the flange and O2. I already changed the lambda for the cats from the stock 0.70? to 0.85, but it didn't do anything.

[murfie]

I don't think it looks at any actual temperature. It just uses the current load and RPM then the temperature in this table. The stock temp values are 1700*.

stock you would see fuel over ride at 3500 and thing more than 1.8 load. at 4500 rpm anything more than 1.1 load. At 5500 somewhere between .7 and 1 load. anything more than .7 load.

If you raised these to the max 2048* you wouldn't see fuel over ride till above 6500 and 1.8 load.

In your guide I saw 1900* as the set temperature. Id say anything above 1.8 at 5500 rpm and 1.3 at 6500rpm. Raising boost is it very easy to raise load.

[metroplex]

But it still doesn't make any sense if my cat temps are well below 1000F when this occurs. I could see it dumping more fuel if there was a lambda setting, but I don't see any other than for the cats and I raised that to 0.85 - that table refers to temperature as well. Even at 1.80 load and 5000+ RPM, I'm nowhere near the temperatures on that table.

I've already been running with the flange temp control disabled.

What would happen if I disabled the cat and O2 sensor temp controls? Should I even be worried with actual lambda being 0.80-0.81 when 0.85 is commanded at 5500+ RPM? It just seems to be a tad richer than what I was expecting.

[murfie]

The temperatures in that table are what the ECU thinks your exhaust components are at. lowering them will make it think things are running cooler and no over temp protection occur. These are not the temperatures at which over temp protection happens.

Disabling cat and O2 sensor temp control may shorten their life expectancy.

.8 and .81 are close to the commanded .85. luckily you are on the rich side. ideally you want what the ecu commands and what you actually get as close as possible.

[metroplex]

Ah I see, I kept that table entirely stock for what it is worth.

[metroplex]

How much should I lower the values in the table? Should I just focus on the 5000-5500+ RPM range at high loads?

[metroplex]

I lowered the values in the table but still no dice. The actual lambda dips down to 0.79 (commanded 0.85) at 5500-6000+ RPM

[Bugasu]

STFT? Log?

[metroplex]

STFT looks fine up until that region, then it is as low as -8%.

[02reaper]

Did you figure this out?

[metroplex]

Nope. No rhyme or reason why it does this other than the speed density needs to be tuned. That itself seems controversial, without a confirmed DIY procedure

[metroplex]

I went to the track and it happens really only above 5000 RPM. Anywhere else, the actual lambda seems to follow the commanded lambda very well.

[02reaper]

Under max enrichment-50128 in the cat/lean cruise tab...It seems to go to this table to me around that rpm also, so I just set it to whatever lambda I want and it seems to solve this for me.

[metroplex]

I had it set to 0.85, but it isn't shy dropping to 0.80-0.82 above 5k RPM.

[SultanHassanMasTuning]

there is a table for minimum lamda

lowest lambda value

[metroplex]

Already set to 0.85. It will still dip below this value.

After taking the car to the track, I've noticed that the 5.5k+ rpm actual lambda gets richer with more boost. As I turned down the boost, the STFT came closer to 0 and the actual lambda followed commanded lambda more closely. So instead of -10 STFT at 18 psi, it will drop to -5 STFT at 16 to 17 psi

I did more research and found a site that discussed negative STFT with increased boost. It indicates the turbo is past its efficiency at higher RPMs and the boost should be lowered.

[96gt4.6]

I'm having the opposite issue myself......

I have my Lambda override AFR set to .82, my wide open fueling target lamdba to .82. Yet, during a pull, my targeted lamda keeps climbing. I'm not sure what i'm missing here. This is on 15-16 psi of boost, all I have done is leveled the boost out up top by moving the load limiters and turbo airflow values up, in addition to extending driver demand WOT values (last two columns) to hold peak torque all the way to redline.

There has to be something i'm missing here, although every table I could see under fueling is set to a different target AFR.

My stock log does not appear to have this issue, it seems to hold the lambda better, however I do need to complete a dig to top of 3rd pull to make sure on that.

This is on a 2015 F150/3.5 Eco. I have several vendor tunes for my truck as well, and all of them are doing the same thing, the only difference is they targed a lower AFR to start off which in turn keeps the actual AFR below 12:1 on a pull, however at the top 2nd and most of 3rd the commanded AFR keeps climbing by around .5 lambda.

[cjg454ss]

did you try richening it up 1 full point at the rpm it goes lean and see if it helps?