Morning to afternoon tune

[ol boy]

Some more thinking on this. The motor has a turbo attached to it. When the oil is cold the turbine will provide more restrictive path for the exhaust gasses as the turbine is spinning slower. As the oil gets hot(above 220*) the turbine naturally spins higher and has less back pressure on the engine. Could this account for the rich in the morning and lean in the evening? My injectors are a bit big for the motor, deka 60's. PW is always between 1.1 and 2.0 for normal non-asshole type driving. This doesn't leave much room for any variation in IAT, BARO, BatV to cause the +-5% ego correction.

Whats funny is under boost the AFR hits the 11.5 number every time no matter if the engine is hot or cold.

Anyone have any data on exhaust back pressure vs AFR?

[ol boy]

Did more think on this and noticed today from the log that only after a short burst into boost did the car start running leaner. I pulled the FPR apart and found the spring cup shifted off to the side of the diaphram and seems to have been this way since inital assembly. There was a crease from the cup on the diaphram showing the missalignment.

Yesterday i found compaired a morning drive to evening and found a point where rpm, load, afr all matched but pw1 and egocor were 9% off. Ill see how the morning drive pans out.

[ol boy]

Just another update...

Years ago I added a BT widget(RN41) and 3.3v reg to the 5volt supply. I noticed that MAP, BAR, CLT,MAT always had some noise on the lines. I could measure a small amount of AC signal on the 5 volt rail. So last night I removed the BT and 3.3v reg. Suddenly things have smooth out and seem more normal. I had to retune the VE table a little bit this morning so we will see what happen on the drive home tonight.

Ryan

[Tjabo]

This is an interesting thread! I appreciate you continuing to update it.

[rickb794]

Can you power the 3.3v reg off the switched 12v input to the MS?
That would somewhat distance it from influencing the 5v ref line.
If the regulator or the BT widget is really noisy you may need an alternate power source.

[ol boy]

I'd have to dig around for the part number then find the data sheet. it's just a TO-92 package LDO reg. Looking back at what I did wasn't smart. I didn't filter the incoming 5 volts and didn't filter the output to the BT widget. I measured the 3.3v rail once and it was +- 0.5 votls as the BT would cycle from asleep to wake and back. Even a small load like a 180 ohm resistor and 33uf cap would have made the output stable when the BT was in low power mode and pull less draw on the 5 volt side. I should also mention I'm not using the stock V3.0 regulator. Using a OKI-78sr, switching 7805 replacement. 1.5 amp output. I sure there was conflict on switching between the two regs.

I'm over BT for now. I need to do more testing and driving to see if this truly fixes the tune.

[ol boy]

I'm still chasing this issue but I think I finally found whats going on. I drove to a cruise in yesterday on the far end of town and back to the house. I compared the two logs and found several points where RPM are within 10, TPS the same, MAP the same, PW the same, Baro the same, aircorr the same, but ego correction was 97% on one log and 103% on the other. Mind blowing! Looked a battery volts... 13.7 and 14.3.. well crap.. Inj deadtime of .821 and 0.749. Funny how the EGO gets the PW back to the same value with 72us difference in deadtime. With a voltage change of 0.6 and 6% change in fueling... what should the first guess at the new ms/v value be?

I'm running deka 60's. 0.850 ms at 13.2 and 0.100ms/v. I lowered the ms/v down to 0.080 which should fatten(or maintain) the AFR for higher voltage. Can anyone confirm or deny the ms/v value for deka 60's. I can find open and closing times all over the place but nothing about the voltage compensation.
My feeling is with this large of an injector on a 306 Ford the pulse widths are pretty small, 1.5ms at idle and 1.6 to 2ms at freeway speeds. 10us will move the AFR around some.

Thanks Ryan

[Tjabo]

I can't help with actual deadtime values, but I want you to know that I appreciate you posting this, and I'm one of the ones watching! Very interesting stuff!!

Seems like I used to have a clue how to figure out dead time somewhat back in the day, but that may not be true. I sure can't remember now.

[LAV1000]

Take a look at this:
https://www.youtube.com/watch?v=lJgi8l-2XG4

If you measure deadtime and fuel flow on the system that runs the injectors.
Then you get spot on figures for your setup.

You could also use the weight of the fuel instead of the volume, get the kitchen scale from the missus
Though you need to recalculate on the weight vs volume if you want the volume.

[ol boy]

Little bit of an update. Installed a fuel temp sensor so I can track whats going on as I drive around. Hot starts are interesting. Temps will be as high as 165ish on the first reading as fresh fuel pushes through the rails. Over 60 to 90 seconds the fuel temps fall down to 100ish degrees. This follows the hot start running lean issue for a minute or so. I wrote some code on my GPIO board to change the CANPWM value for the flex fuel input based on the fuel temp. 70*F is 100% correction(1875), as fuel temp goes up so does the correction(CANPWN gets small "higher freg" more fuel). My drive to and from work are too short to see much change in fuel temps, so this will take some time to sort.

[ol boy]

Another update, Fuel temp seems to be 90% of the issue. I've found some documentation on the fuel blend here in Southern Arizona. During the winter months Ethanol is added upto 10% by volume and during the summer months none is added. This could account for my overall summer to winter tune varying by so much.

http://www.pinalcountyaz.gov/AirQuality ... bution.pdf

[prof315]

Another update, Fuel temp seems to be 90% of the issue. I've found some documentation on the fuel blend here in Southern Arizona. During the winter months Ethanol is added upto 10% by volume and during the summer months none is added. This could account for my overall summer to winter tune varying by so much.

http://www.pinalcountyaz.gov/AirQuality ... bution.pdf

I think you've nailed it with the fuel temp ( varying ethanol content is also going to affect things). I guess that's why the OBD2 standard for fuel trimming is 25-30% before a check engine light sets since not every car has a fuel temp sensor in it.

[rickb794]

Another update, Fuel temp seems to be 90% of the issue. I've found some documentation on the fuel blend here in Southern Arizona. During the winter months Ethanol is added upto 10% by volume and during the summer months none is added. This could account for my overall summer to winter tune varying by so much.

http://www.pinalcountyaz.gov/AirQuality ... bution.pdf

Im thinking that document is old 10+ years

I believe the feds want you to have E10 in everything now days.
And it is going to E15 soon.

[prof315]

Im thinking that document is old 10+ years

I believe the feds want you to have E10 in everything now days.
And it is going to E15 soon.

Up to 10% Ethanol and I have used flex sensors to check, the actual content in my area ranges from 5% to 18% and does change seasonally .

[ol boy]

Found a more recent pdf from 2013 of the proposed CBG requirements for Az. It lays out the same ethanol content by month by region.

https://legacy.azdeq.gov/environ/air/pl ... 13sip2.pdf

ARS 41-2025 requires all gasoline supplied or sold in Area B [i.e., Pima County areas outlined in
A.R.S. § 49-541(2)] to have a minimum oxygen content of 1.8 percent by weight from September
30 through March 31 of each year. This requirement is an incorporated control measure for the
Tucson CO planning area.

During the coolish months the fuel needs to have a minimum of 1.8% oxygen. How much ethanol is needed to get to 1.8% of a gallon?

So in short... run a flex fuel sensor even if your not running E55-85.

[ol boy]

https://agriculture.az.gov/sites/defaul ... 3.2017.pdf

and RVP

https://agriculture.az.gov/sites/defaul ... ards_0.pdf

fun fun.. looks like everything is still in place from 2010ish

[rickb794]

It is near impossible to figure out that mess.

The Clean Air Act mandated that gas be reformulated, then some areas were deemed exempt and other areas Opt'd out.

And that appears to have changed as well. Might be due to the ability/expense to distribute Ethanol (government cheese) to remote areas. Or some states had better lawyers....

At any rate there has always been seasonal fuel in some areas, that is not going to make a difference from morning to afternoon, only twice a year when the fuel changes.

[ol boy]

rickb.. if you read a few posts back I figured the change was entirely based on fuel temp. I do have a thread floating around somewhere talking about the difference in tunes between summer and winter which would follow the gas blend change.