Tacoma - OVTUNE - VFTUNER - Update Info and Original Development

I just drove my truck around for about 50 miles on the stock tune. It was not fluttering any. I will give it a week to make sure. I have alot of driving to do the next couple of weeks. I should be able to put about 500 miles on it next week. I will be patient with it next time I flash it. If it starts fluttering on the stock tune, I will make the dealer fix it.

 

Can you give more details of the flutter? I have not noticed it stock or with the tune.

 

I have a flutter when I go through town right at 40mph. It usually happens when I've gone down from 60 to 40 once the speed limit changes. It's like it trying to decide whether or not to downshift about 3-5 times a second until I let off the gas or give it more gas. Had rev1 done.

Edit: all stock, have not purchased tune yet.

 

I know it was brought up, but was it ever confirmed that the tune could provide speedo calibration?

 

That would be awesome if it does or could be made to do that in the future.

 

OVTune has not confirmed it can be done. I have asked a few times.

 

Would save me a couple hundred bucks if it could happen.

 

I don't know if you have ever been to middle tn, but we have alot of small rolling hills. Too much for 6th gear but most are fine to go over in 5th gear at around 50-55 mph. So you go down a hill and you are barely loading the engine or not really giving it gas. When you go up the next one, you have to barely give it gas to get over it. When you barely give it the gas, it's almost like it starts missing for a half second to a second or so and then it smooths out. If I put it and 6th and lug the engine it won't do it. If I down shift it to 4th where the rpms are higher it won't do it half as much. It also does it on flat highway. If I am on the interstate doing 80 in 6th gear and I let off the throttle for a second or so and get back on it, it does the same. I thought I may have been lugging the motor some but this is very light load on the engine. If the ac compressor at these moments it almost feels like it going to quit.

 

These surges are present in the stock tune too, just muted. It may be that they spent time focusing on the stock tune to mask a mechanical problem which would naturally become worse when you're not aware of what they were trying to hide and tuned in the 99% of driving conditions.

 

Is the area of RPM this is happening at around 1200-2500 RPM? Your explanation sounds as if the light throttle and on / off throttle is bouncing the target VVT right in and out the lowest area of valve retard.

If anyone else experiences this please let me know i'll look into it right away

 

No way.. the AT sucks on uphills in D. This is my only complaint with the truck. You can work around with S-mode and ECT but it absolutely sucks ass in D so I've gotta assume a MT is much better
When the truck needs to be in 3rd, it'll upshift to 4th and you immediately lose speed and it'll downshift back to 3rd. Once you gain your speed back, it'll upshift again and continue on this jerky shift loop the whole way up the hill. It is Fucking retarded in D. The thing is, it won't do this in cruise. So it seems Toyota has figured out how to eliminate the shift loop in cruise. Don't know why they can't apply that knowledge when programming D mode!

 

Mine is stock and is around 12-1400 @40mph very light throttle.

Edit: sounds like you could be right in my case..

 

It's

It's probably around 1800 to about 2500 rpm or so. If i stand on the throttle it is fine. It's just under light engine loading. I was trying to look at the engine loading on my scan gauge. Maybe 15-25 percent engine load. If I am outside that rpm range or loading the engine more it won't do it.

 

Yes!

Now that it was described I do recall having that same surging/fluttering on the stock tune. It was definitely not as pronounced.

With your tune I noticed it in 3rd gear almost exactly 2000 rpm with steady 1/4 throttle up a slight hill.

 

1000 to 2400 RPM with 2000 to 2400 RPM specifically there are wide changes in valve timing dependent upon load. In that range is it very easy to bounce valve timing targets in and out of atkinson mode. Large fluctuations in valve timing without much change to RPM (which the valve timing, controlled by load, will be changed directly by how much accelerator pedal you apply) can make the engine feel this way. Mazdas do this same thing.

I have a big update coming in 1.02 for intake valve timing. To me, it makes no sense that atkinson mode starts at idle first off, and the peak (maximum cylinder waste) is actually at 650-800 RPM and large swings in valve timing right at the next load increment.


The valve timing targets are not smooth, gliding targets. It's a a cliff like drop right off idle, and right as you approach mid load valve advance doubles, then doubles again, then doubles again. at 1000 RPM you can go from no valve advance at all to nearly maxed out advance with only a 20% change in engine load.

Toyota seems to have been a little lazy with this calibration. There does not seem to be any compensations or calculations to strip or smooth valve timing, nor different targets based on vehicle speed. As a result, Valve timing is going to be clunky because the way the engine responds does not change based on anything except load and RPM.

Unlike other vehicles with this same style of camshaft control, where there are several maps that work together and independently along with comparison maps to calculate what would be most suitable for the engines speed and direct injection angle, and disable valve advance that would be undesirable for response based on vehicle speed.

 

Looking forward to it! I'm going to stick with the tune until then because the issue isn't serious enough to cause a problem.

Thanks for explaining the cause. It makes sense that it would be the cause.

 

Long shot and hate to interrupt the Atkinson talk, but have you figured out if speedo calibration is possible via tune?

 

not yet sorry

 

@OVTune
Would this engine benefit anything from a larger bore throttle body?

I noticed that a Tundra 4.7 76mm throttle body shares the same connectors but has a different mounting flange. URD makes the needed adapter.

Have you looked into this?


3.5L 70mm throttle body


4.7L 76mm throttle body


URD adapter

 

I am hoping this is a "no" because it would be seriously bad for my wallet.