Engine accelerates at 1500 RPM preventing engine braking when going downhill

Interesting, i swear i could do that. That blue mpg line would dissapear, meaning 0L per 100km. Only times where when coasting to a red light in 6th. Otherwise i did feel it once in a while when actually engine braking.

Love my new tune BTW All i wanna do is drive now.

Actually i found a pic with proof. I always coast down from this bridge in 6th and the DFCO is engaged till i throw it in neutral. That blue line dissapears when the DFCO is engaged. I could go to about all the way down to about idle rpms no problem. This was stock tune.

 

If you watch the Instant MPGs outside of the center display, coasting while in Closed Loop will often produce numbers greater than the max 30mpg shown. The max instant that I can see on OBD is about 65mpg.


Same here. I look for excuses to go for a drive.

 

1st gear will still do the 1500/2500 cycle, even with OVT 2.0.
Try it going down a steep-ish hill in 1st, full lift.
2nd was modified by Mat so that DFCO cut in is below 1000 rpm

 

Did you see the pic that i edited my post with? The DFCO would turn off on a flatter part of the bridge, than engage again when it got a bit steeper. All happening around 1100-1200 rpms. I know for certain that when the blue line dissapears, the DFCO is on.

 

What rpms is is set for the other gears? Just curious.

 

I don't know what to tell you other than there are three fuel modes. Closed Loop, Open Loop, and DFCO. The stock gauge is a rough approximation with a limited range.

 

2nd through 6th are all the same. Near idle. 1st is limited, a bit lower than Stock, as another function is blocking the DFCO change. We are hoping to get 1st corrected at some point in the future.

 

You seem to know a lot more than me, so i could be totally wrong

 

Ill go out today and fuck around with DFCO some more, im more curious about now. It honestly never really bothered me, even on the stock tune. Ill report back later on with my findings.

 

Hook up with Torque or OBD Fusion. They are very informative. While Datalogging with OVT software is damn good, it is quite hard to monitor the data real time.

 

If it didn't bother you, then there is nothing to worry about.

Our desire all stemmed from the sudden lack of engine braking and the unpredictable nature of it. I never experience a similar issue in our other EFI, ETB, and / or DI cars. DFCO was always predictable and benign. OVT fixed 90% of it on 2.0.

 

Well you guys got me curious now

 

Assuming here, but I notice the DFCO IN 6TH every morning on my drive to work in 6th with my cruise set. Long downhill stretch and if I'm set at sat 63, she'll drop to about 60, no fuel, than kind of snap out of it, then back and forth. Weird thing is I can keep the speed anywhere I want with the foot on the same stretch. This got more noticeable after OVT, FWIW.

 

I go down an extremely long steep hill upon leaving my driveway, In any manual transmission vehicle, if I have a glazed clutch, it has the exact effects as you described.

 

I have not noticed this with my 6MT and I engine brake all the time in 4hi/4lo 1st gear. I’ve never bothered to look at the tach though.

EDIT: perhaps the difference is that I generally also feather the brakes to control the speed.

 

I had that on the Stock tune. It was one of the first things that I noticed that was changed when loading 1.05b. It came back a bit in 2.0.

Honestly here, I don't think this is DFCO, but just tip in settings of the tune as it would happen much faster than DFCO normally cycles. It doesn't engage until completely off the throttle for a couple seconds. The areas that it would do the back and forth were downhills where just a bit of throttle was needed. Not a full coast.

I can also confirm the tip in side of things as I made it worse than ever on my first vF tune edit. See my V1 Air Load Control maps here:
https://www.tacomaworld.com/threads/ovt-vf-map-edit-air-load-control-alc.685741/

I over-smoothed the maps at tip in (0.0%) at about 2,000rpm. That totally hosed up CC and normal driving. Easy fix though, once discovered. The V3 and V4 maps are friggin' great though.

 

i noticed same on my 2019 trd offroad automatic. In 4x4 lo, 1st gear, it would do the same. I recently took a 2020 jeep wrangler on same trail, and guess what. Same exact behavior. So it's a design thing i think for a reason. haven't had the titan down that trail yet but when i do, i expect same maybe but it's a v8 so who knows....

 

Seems like I peaked some interest. I really appreciate all the feedback. The sole reason I bought the 6MT instead of the AT is my driveway, it is fairly steep in places. My old Mazda B2600i 4X4 does not have this problem. Admittedly it is very old Tune Port Fuel Injection (Need acronym) but it will crawl down the driveway with the foot off the gas where as my 3rd Gen literally flies down forcing my to ride the brake. Makes for slippery fun when the driveway is icy. 4L becomes mandatory at that point so the lack of engine braking is a little less disappointing.

Will putting slight pressure on the accelerator prevent the DFCO from cycling? I will have to try it in the morning.

 

Is this a post 2017 thing then?

edited I said 2018 earlier...

 

No. That will ensure that the injectors stay on. In fact, I have found that a slight tap of the brakes will encourage DFCO.