Question about timing, millage, and power

With the 4.0, you might get a little more advance running premium if you aren't already.
The 2.7 runs the same timing map on any fuel (though will retard if it senses knocking), but the 4.0 will advance a bit on premium.

 

Seems that a lot of them on here tend to get insulting.

 

If the Op is wanting better mileage. Why switch to 10 ply tires. Thats only gonna decrease mileage. They are twice as heavy as the stock dunflops. Oh and expect to get around 30,000 out of the stock rubber.

 

Not an expert by any means and I don't know what you are building for race engines or what fuel you are using. Looking at a cut away of the 1GR-FE found at Yota-tech the combustion chamber looks very compact with a fairly narrow included valve angle, good squish along the perimeter of the pistons for added turbulence. I would think that they would have pushed the timing to the max for average available fuels and engine life. There is always a trade off in design. Maybe it could take a little timing advance in an environment were nothing changed. Always 60*, 60% humidity, 29" atmospheric pressure. Maybe they could have added a few more sensors and a larger faster computer so that timing was always at the optimum for each ignition event but there are other factors that enter into design, such as being price competitive with the competition.

 

Always ran max PSI on sidewall for all of our trucks in the past, including a 84 Bronco hunting rig with 10 plys.

 

Well running that last tank with them aired up the the max pressure written on the tire [51#] netted me another 1.5 mpg and feels to turn nicer, only noticeable downside would be ride quality. It rides noticeably rougher but nothing crazy the factory bilstiens [sp] sorry shity speller lol] seem to be a good shock. I ran premium 93 oct with a oct. booster as well to see if really increasing the octane level a good ways would allow the ecm to call for more timing. Not sure Ive noticed that it runs at any more timing but it feels to runs better and millage was up, was it the tire pressure or octane or the combo of both?

 

I have a question. Why do you think the ecm can recognize the higher oct and thus increase timing? What sensor can detect octane?

 

Your timing sounds fine to me there is nothing to tweak it is written into the software and cannot be changed and unless you like to waste money don’t buy into any “chip”.

 

I have no idea, this was solely based on info that another member touched on.

[With the 4.0, you might get a little more advance running premium if you aren't already.
The 2.7 runs the same timing map on any fuel (though will retard if it senses knocking), but the 4.0 will advance a bit on premium.]

This guy has answered a few questions for me already and has seemed to know what he was talking about. I appreciated the info and thought Id give it a shot once. It runs noticeably better no dought about that, question is does it allow an increase in timing? If it did that would explain why it runs better and posably a bit better milage?

And ya I agree Ive read enough now on here to know about the 'chip' thing with our trucks.

Im happy enough with the truck just as it is, power is adequent and milage is just what it is.

 

The 4.0 was designed to run on premium. It will run acceptably on 87, but the knock sensor will cause it to retard the timing.

The 2.7 was designed to run on regular and it will not advance the timing beyond where it is running regular even if knocking is not detected.

It's not 1980 anymore.

 

This ^ is possible but I still would like to see some hard facts. It will only retard the timing if it senses a knock, Toyota says 87 or greater octane. So if it does not knock with 87 the timing is as high as it can go any way because it does not detect a knock. Mine is a 6 spd if you want to make it knock just floor it in 6th at 30 mph or stall the converter with an automatic. Mine does not knock running 87 or 91. I some how don't see how it would inch up the timing to suit the octane retard it yes to do so would involve some type of intelligence written into the software that would be of little use other wise higher timing has a tendency to increase NOX and I'm sure the line is drawn at emissions.

 

Here, read this, most helpful in understanding what/how to tune the 1GR. Do note that it was written in 04 though.

www.gadgetonline.com/U-Tune.pdf

 

Wow that's a long and very good read. I wonder if that info [the way Toyota tunes] is still current now 10 years later?

 

...that's a question for Gadget at URD. I would suspect that most of the info is still good. There is a good section on how timing is set and it makes sense given what I've seen.

 

It was more out of curiousity than anything, I think I'll leave it to the Toyota engineers to tune my own ECM. Truck runs great and I will adjust to driving it. Its just my racing background and mechanical nature to question it when I feel it struggling at a giving point and notice that its running at 16* when you think it should be around 30*. Or when you have the cruise on the hwy set to a ridiculous 55 mph [trying to get great milage] and the timing is still hunting between say 18-24* and you know damn good and well that if it were up around 30-32* that milage would be up where we all would like it, or closer to it. Just an opinion from the new guy with a scan gauge II and a new truck. Ha

Ryan

 

It's all good, I was doing somewhat of the same thing a couple of years ago when I was trying to see if premium made any difference. When I was running premium I could see no mpg differences, so I went to the SG to see if I could see any timing differences. I could see none...

The linked doc also detailed how the timing parameter gets changed. It was interesting to me that if you stayed below about 3k rpm, the timing parameter would not change based on the knock sensor.

BTW, the only way to modify the timing that I have seen is with the APR tuner. That tuner included a set of timing gears. But the APR only works on pre-09 Tacoma ECUs

 

Yes sir I agree. My problem with that is I always stay below 3k so I never get that detailed timing map. I feather off to get the gear change around 25-2700 trying to improve milage. I wished their program was from 2k and up rather than 3k. I bet it would further help milage and low speed torque, would you agree

 

If you know where the timing should be for any given fuel mix,load, speed etc then perhaps you should sell your self to Toyota. It ain't cut and dry. The systems have evolved far beyond turning a distributor and re-jetting a carb this is one of the reasons chips do not work well with modern gas engines they are pretty well at max for economy and emissions. Sure you can tweak a little bit more power but then when it's time for the emission test the story will change. You can fuel it higher fuel will cool the cylinders then you can run higher timing of course your HC will now be thru the roof and the higher timing will produce more NOX but who cares I just gained 3HP and got .2 MPG better mileage.