2016 OVTune Tacoma 3.5L Manual Transmission / Engine ECU Reflash

I'm using a Carista dongle and OBD fusion. I paid extra for Toyota specific PIDs (10 bucks US in App purchase IIRC), which include things such as exhaust and intake VVT target angles, change angles and so on for both banks. There are literally hundreds of data points to choose from lol.
Yeah and I don't know what mode the engine is in when DFCO is active. I've reconfigured my Fusion dashboard to show intake and exhaust VVT target angles, accelerator posn, throttle position, AFR and misfires. I'm going out here in a bit and will monitor.

 

Your comparing a machine witch is 1/4 or less in weight.and the higher engine to weight ratio the higher the braking.
As far as throttle plate goes,you think the more open the plate the less the braking?
My reference to any sort of engine braking was to show the reason for that demand in that industry.only recently have they become optional in 2ton plus pickups but again your looking at 500$cad pr axle for brake job.
Unless your trans porting heavy load 24/7 I really don't see the need for any engine braking at all.

What are you guys getting on front pads and rotors anyway

 

Ok so some mixed results on VVT angles. More DEFCO fodder:

1. Idle:

- Throttle Position (deg): 1.8 - I'm assuming this is in addition to the 7 deg when the throttle plate is being fully held back by the spring?

- Intake VVT target angle bank 1 (deg): 30

- Exhaust VVT target angle bank 1 (deg): 0



2. Full lift, 5th gear slowing down from 80KMH (AFR pegged high = DFCO)

- Throttle position: 1.8

- Intake VVT target angle bank 1 (deg): 30

- Exhaust VVT target angle bank 1: 0

Hmm so idling and DFCO give the same VVT angles and throttle position.

I will add that driving around on the back roads at light throttle in high gear resulted in intake VVT angles of 8 to approx 25 (presumably Pseudo Atkinson mode). Downshift to 3rd and go WOT, max intake VVT I saw was 70 deg - this should be OTTO mode.

Sorry guys, I haven't invested enough time with the OBD fusion app to get log files and appropriate charts so that this can be visualized properly. Also, my home button on the IPhone is fucked so getting screenshots of the Fusion dashboard is a challenge lol.

Thoughts?

 

Ill bet your EFI system turns fuel off when off throttle on that bike unless its from the 90s. Only the earliest EFI systems did not shut down its injectors, these systems were a small step up from carbs. Its also hard to compare the engine braking of a motorcycle to a car, very different torque to weight ratios.

It will absolutely kill fuel consumption, 100%. Everytime you go off throttle it would still be using fuel, it would easily take a few MPG off your total for a full tank. I run my track bikes with no cut on its injectors and yes it helps smoothness when just cracking the throttle but its not worth the drop in mileage alone. When off throttle your ignition system shuts down, if your fuel injectors keep firing that fuel goes through the engine, out the headers, and either burns in the header tubes or inside the cat. This raises exhaust temperatures and causes the cat to run way hotter then it should.

Rev hang is going to be mostly down to rotational mass in the engine, a lighter fly wheel will help the most as will lighter pulleys. Some of that hang may be a bit of software but most of that hang is going to be a physical limitation. There is usually something referred to as overrun cut delay this is the delay that the injectors are shut off after letting off the throttle (usually done by manifold pressure vs rpm). Longer delays make on off transitions smoother but can induce some rev hang. Reducing cut delay is tricky because if you reduce it too much it becomes harder to drive smoothly during on off transitions, it will become jerky to drive. There is usually another similar parameter around closing the throttle faster after letting off. Then you have things like tip in fuel which will add a little extra fuel as the throttle is opened so a lean condition doesnt occur. This is all moot if the fuel tables are trimmed like shit though. Its a fairly complex problem and there are a ton of settings and parameters which makes it a hard problem to solve as some people are fine with the hang and others arent, its one of those things that is hard to make everyone happy with.

EDIT: Most cars disable DFCO at around 1200RPM, this is pretty standard since its about 500RPM above most idles, this is so the engine has a change to start firing and doesnt stall on you.

 

The throttle position numbers above are the pedal or throttle body? Also, this is for the OVT?

If it is for the throttle body, then that is very different than what I see on the stock tune. If it is for OVT, does the engine braking feel better or the same?

I would agree that the higher intake angles would indicate Atkinson.

 

I monitor both accelerator position and throttle position in OBD fusion. The numbers don't change at the same time, or at the same rate. Accelerator is always the first to react.
I'm tuned, 04B10 1.03 test file.
Damn, it's been a long time since I've run the stock tune.. I don't think there's any difference in engine braking TBH.

Did you mean higher intake VVT angles indicate OTTO? The highest numbers I got were at WOT.

Idle and DFCO condition seem to be almost in the middle..

 

It's a 2001 Ducati ST4 with a very simple Magneti Marelli EFI. If it is set up incorrectly, we get lean popping while coasting at all RPMs. There is also zero lag when rolling on. A single misfire on that bike is very noticeable.

I have diagnostic software for it, but can't log or be used while riding since it connects through a laptop. I will see if I can find a definite answer.

I agree that it is apples and oranges. I was just trying to state to the previous post that opening the throttle decreases engine braking. The opposite was said above.

 

Interesting. Then, I think you are seeing different throttle numbers than @luminous and I?

Sorry. I meant the 30deg intake angle at idle. That would indicate the extra intake valve opening time, right?

Under heavy load, I agree about being in the Otto cycle, but I have no info about what VVT is doing there. All I know is that it feels good. Hahaha!

 

Well, it could be the App/PID I'm using. I'm in no way an expert, so I may very well be using something different.
Understood, I misread what you said.
The way I understand this system, there's quite a wide range of VVT angles on the intake cams. One end of the range (full retard?) gives the max time after BDC on the compression stroke that the intake valves are hanging open, thus allowing the piston to push some of the air charge back out of the cylinder (reducing compression and pumping losses = Pseudo Atkinson). OTTO (full compression and power) should be somewhere closer to the other end of possible angles.
Anyway, it seems during DFCO, intake VVT angle is somewhere in between.. I'm not sure any of this helps in the debate, but I had to know lol.

 

Haha! It is all good information and discussion.

 

is it possible to get any higher temps in cat than high way driving were defco is rarely on? i would think that city driving would see lower temps and thus handle the extra temp,i dont know butt makes sense as a mater of fact my understanding of the purpose of rev hang is it dumps fuel into cats to keep temps high as the engineers believe low revs pruduce extra emissions.hence the lac of exhaust rumble on decel in these trucks ?

as for fly weel being heavy or light makes sence but these trucks have sufishant rev drop when reving over2700 rpm so i dont see fly weel weight
being the problem.its when reving only to aruond 2500 we have the rev hang.

as for fuel loss beleave killing rev hang and defco cancell eatch other out pending driver habets and routes.your observation on defco kick in range makes total sence

 

As for the reason Rev hang has been implemented, check this out (scroll down a bit to where they talk about emissions):

https://www.carthrottle.com/post/rev-hang-explained-and-why-petrolheads-hate-it/

 

yes thank you.read an article some were way back just after buying this truck after thinking the truck was a defect,dealer didnt even know about rev hang drove me crazy.ok now were on same page call Mat! lets get this shit done?

 

Regarding DFCO:

My truck doesn't DFCO... anymore; but, I still have one of the highest MPGs of any V6 4x4 (Auto). I don't think it makes much difference in normal driving (i.e. no mountain downhills).

Why no DFCO anymore? I drive short trips. I think I'm in or near the injector cleaning zone. It used to DFCO and then it didn't... twice. First, when new I drove on a long vacation, after coming home to my usual short trips for a while... it stopped. Second, I had the dealer reset the learning. DFCO was back. After 1000-1500 miles of my usual driving... no more DFCO.

 

Hmm interesting..

I run OBD fusion and a Carista BT dongle most of the time, and I can tell you every time I lift (above approx. 1300 RPM) the AFR pegs high (it only reads to a max of 18).
Do you mean you don't get the "surge" or decrease in engine braking when slowing to a stop?

 

Check your injector pulse width values, if they go to zero its cutting fuel.

Edit: Sorry just noticed you said its an AT, cant compare DFCO on an AT vs MT. They are very different between transmissions.

 

Anyone know what lead times look like right now?

I placed my order and was charged almost 3 weeks ago. It's been radio silence since then. It didn't say out of stock or anything when I placed the order. I know Matt is busy, but going on 3 weeks and hasn't shipped yet seems like a longer wait than it should be.

 

not certain but it looks like another round of files is imminent from dev & dyno work recently. if that's the case you're probably on the hook to wait until that next version is released, rather than getting the last version. so, you know, hurry up and wait. it will be worth the wait.

 

Thanks for posting this explanation of rev hang. After 30 years of driving stick, I was wondering if I had suddenly developed a weird inability to get off the gas pedal!

 

For now, I only have a ScanGauge II. Under DFCO it shows 9999MPG and 0.00GPH. I don't remember what AFRs I get, I'd have to check.

But, yeah the engine braking is useless once DFCO stops. It was annoying me in a rental Camry I drove all over CA. I don't remember what rpm it stopped; but, IIRC it would not DFCO again until 2k.