Tacoma - OVTUNE - VFTUNER - Update Info and Original Development

A locked diff can reduce steering response. Once you do start to turn at least one rear wheel would need to slip (loose traction) to turn. Think about getting up to speed in a straight line and needing to turn. Vehicle resists turning and could snap to tail out.

Fun when you're wanting that, less so when you weren't.

 

The other wheel just spins slower. It doesn’t lose traction. But a locked rear diff will make turning more difficult but not impossible

 

Locked, means both wheels spin at the same speed. The inside wheel will want to spin slower while turning, but can't, because - locked. At the very least you will scrub tires with the diff locked going slow. At higher speeds, I can see how there could be reduced steering response.

Unlocked, yes, the wheels are allowed to spin at different speeds.

 

That’s what I was trying to say

 

FWIW, I average 4 to 10 misfire per drive cycle, 90% of them occur within first few minutes when engine still coming up to temperature. 1.05 91 04B04 using 91 gas, stock TRD Pro.

So for me, no difference between stock or OVT tune. Not denying your problem, just throwing more data out there. Perhaps bad gas? Try running 87 tune with 91 gas, or fill up at another station. Questionable crank position sensor (CPS)?

 

That's what I get, around 4-6. 1.05 91 with 91 in the tank. I get maybe a couple more on 1.05 than I did stock. I would also be curious to see people's results when they run higher octane on a lower tune. Like the previous poster said, 91 on 87 tune.

 

Could be a fuel issue. However, significantly less misfires on the stock tune vs 1.05 87, same fuel in tank. I need to fill up and going to try Shell 92 (can't get 93 here), and will try 1.05 87 on 92 octane to see if the misfires are still an issue. I will report back in the next few days.

 

Sounds like a great plan. We’ll be awaiting your results!

 

I would rule out a fuel. I've been running 87 since day 1. During flashing to 1.05 87 I had 1/2 tank and number of misfires caught my attention right away.

 

Locked 2WD might be nice on a wet boat ramp, but for 4LO is arguably better if it's on a steep incline.

 

I've had huge differences in performance from one tank of 87 to the next. these trucks are princesses when it comes to fuel, no matter what tune, factory or not.

 

and temperature!

 

And altitude

 

I have the same kind of behavior and I have replaced my CPS sensor and have far less misfires on stock. It's the tune that's causing the spike in misfires for SOME. Period.

I also do not recommend toying with different octanes on different tunes if you are experiencing misfire and knocking. I have tried that and when I ran the 87 tune w/ 93 in the tank I had knock city and quickly flashed back to stock.

 

So haven't been on this site because enjoying the tune and happy to say. Wow what timing seeing Matt's updated OP.

Couldn't agree more with commitment about the computer illiterate people. That's half this thread.

 

How about Locked 2Lo. With my current setup I could try it...it has never occured to me.

 

I had been running the 91 tune on 93 gas and it had been great. Tried the 87 tune this week, bad idea. Went from Erie to Pittsburgh and it was misfiring like crazy on the highway. If the rpms were under 2000 at any load it would misfire. Had to switch to S- mode and set at 5 to get home without crazy misfires. Got back into town, filled up with 93 and switched back to 91 tune and all seems good.

 

You ran 87 octane on the 91 octane tune? No shit you had misfiring... it is called pre detonation. You prolly took quite a bit of life off of you engine...

 

No I ran the 87 octane tune on 89. I'm not an idiot. Lol I knew I was making a long trip. So I figured I'd try the 87 tune and filled up with 89

 

And I actually had about 2.5 gallons of 93 left in the tank when I filled up with 89 and switched to the 87 tune. My truck doesn't like that tune at all..