UltraGauge Owners

Ignition advance is how early in a cycle before the piston gets to top dead center that the computer fires off the spark plug. It's a tradeoff area, too little (late) means not as much work will be imparted upon the piston, and too much (early) causes detonation. Gotta find the sweet spot. Too late when you're cruising and you're burning fuel but not getting the benefit.

Modern engines use knock sensors to keep them at the edge of detonation (it can hear it). The computer will advance timing until it hears it, back it off a touch, and repeat, using the correction against the factory timing settings to adjust for variances engine to engine. Toyota seems to check once every great while on this truck, which is very odd considering that the point of best timing can change greatly with just a humidity change. The time you know it'll check it for sure is a cold start. It seems to keep higher timing when it's had many consecutive cold start cycles done like what I showed in the video. Throttle input is what cancels this process.

My Honda would advance timing against knock sensor readings every three seconds in closed loop operation. This truck wants tens of miles, not seconds. If a sensor hears one bad poof it'll yank timing and your mileage will randomly bomb out for a day.

Coolant temp vs HVAC...

The heater core gets coolant through it regardless of whether the t-stat allows it to go through the radiator. That lets you get heat when it's cold long before the engine is hot enough to need the rad. Basically, if there is airflow over the heater core, you are cooling the engine on a cold day.

Options are either set the dial to cold (air won't go to the heater core) or turn the fan off (some airflow will if truck is in motion, and you'll fog up the windows without fresh air). A lot of people I know will start their vehicle and put the dial to hot and turn the fan up - and wonder why they don't get heat for 15 minutes. You can't feel warmth until coolant in the core is about 125 or so, and it doesn't feel "warm" until at least 160, so there's no point in cooling the engine before it gets there.

Similar principle if your engine starts to overheat, there's a reason the manual says turn to max heat and put the blower on full blast. It'll cool the engine.

 

Wow, good read. Thanks for the good explaining.

I hadn't thought about the heater core thing, but it makes sense.
I watched the timing this morning when I cold started (eng temp 23F). It made it up to 20.5 and seemed to settle there until I took off. Steady cruising at highway speed, it moved around from 25-28.

 

The PCM seems to reward consistent rounds of that ignition timing check cycle. I've been diligent and it now only drops to 17 and climbs back to 22 every time. 55 mph on flat ground is finally a solid 29.5 and the casual 30. It gave me 18-22 inst. mpg in a 15 mph headwind today, which a week ago was what it was doing with a tailwind.

What I did to make the computer mad... I didn't let it finish that cycle for three consecutive cold starts. Lo and behold, it got mad, throttle input was sluggish for a day, cold idle timing would drop to 5 degrees and only come back to 19 for a while, and it would only give 24 degrees at 55mph. It's more bipolar than I ever expected an engine computer to ever be.

 

So, about 1 minute? What happens if you idle longer? I thought I saw it reach its high around 20.5, then slowly creep back down. Does that make sense?

 

I wish it had tranny temp

 

Ignition advance will come back down as the engine warms up because it's running at a lower speed. Most every idle speed under 900 rpm gets exactly 15 degrees of timing no matter what timing it gives higher speed ranges.

I know mine has done its thing when it's holding steady above 1400 rpm with 21.5 or 22 degrees of advance. If the engine is not cold but cool, it won't get to 21+, so just wait for it to stop rising. It never takes more than a minute or so.

Indeed tranny temp would be nice. Fuel level would be nice too, but apparently the computer is blind when it comes to that. On my Honda the UG would auto-reset the fuel level when I filled it up; now I have to hold that top button for 5 seconds every time to manually reset to avoid inadvertently tripping the low fuel level alarm.

Truck was playing nice today, it was 34F outside on my way home and it came up to 19.8 mpg trip, which tells me this tank is thus far about 20.0.

I wonder how many times the UG has paid for itself by now...

 

Thanks Iroh, that is really good stuff. The best info I have seen on this site in a while

 

So I have a scangauge on my 2005 4cyl and whenever I'm idling it registers 8 on the ignition parameter. When I get up to speed I get reading around 30 but it jumps wildly depending on how I accelerate. Is that normal and how to I interpret this. Great information in this thread.

 

Yup. I drove from Texas to L.A. some years back in a Geo Metro in July. Driving across Arizona in 115* heat and I had to roll down the puke chutes so I could run the heater on full blast to keep that little 3-banger from overheating. Must've gone through a dozen bottles of water and Gatorade. Not fun.

Lots of great info iroh, thanks!

Good thread and I'm sold. Will be buying one of these shortly.

 

The amount of ignition advance that can be given is largely determined by how high the cylinder pressures are (this determines your dynamic compression). Under high pressure, such as high throttle situations, the flame front moves a lot faster so it has to set it off later in the cycle (ideally as early as it can without causing a detonation wave) which shows up as a lower number on your ignition advance readout. Conversely under low pressure such as cruise or idle the flame front moves more slowly so it can ignite the charge sooner to get more work out of it.

In other words, at the same rpm, if all other variables are constant, as throttle is increased the timing advance must decrease.

The advance also tends to go up with engine speed because rpm doesn't determine how fast fire burns. A faster spinning engine can outrun a flame front and can ignite it sooner.

FWIW my v6 always idles warm at 15 degrees. My Honda was 5 degrees. It depends on the engine.

 

So when I'm waiting for my tacoma to warm up how do I watch for the ignition timing that was shown in the video? Seems like mine won't do that. What am I missing?

 

You have to program where you want your gauges displayed. My ignition advance is on Q (third screen) because I only watch it during startup and once I'm done with it I flip back to the first screen.

screen 1 = A-F
screen 2 = G-L
screen 3 = M-R

 

How do you reset oil reminder alarm?

 

Ordered. Anything that can potentially help me improve my current 12 mpg is worth $80 in my book.

 

Fially got it mounted today. I went with a similar method to what babyboi2284 did. No probs with the mounting at all, but have had a couple 'learning curve' issues. After I set up some of the guages how I wanted, I couldn't figure for the life of me how the hell to get out of the menus. Read through the manual nine times and still didn't find it in there. I'm sure it's there somewhere and it's operator error. I was finally able to figure out that I have to back all the way out after about 30 min of swearing.

The distance calibration didn't work on the first try. When I stopped at MM-5 it just told me there was no distance to calibrate. Dunno if I had started out in the menu section or what, but it worked fine on the return trip.

Used a hunk of stiff picture wire to get measurements and contours-



Formed a 6" piece of 1/16"x1-1/2" aluminum strap. Blowes sells it in 4' lengths for a few bucks. Nice thing about it is it's easy to work (cuts with tin snips) yet still strong enough for light-duty jobs like this. Trimmed down the sides so it matched up with the UG mount clip width for button access. Also gave it a quick rattlecan shot of black so it wouldn't draw attention from the outside in the sun-



Used 3M double-sticky on both the guage clip and to the roof brace-

 

Nice job. I installed mine the other day but put it down above the cup holder on the stock flex mount next to my XM receiver. Already saving gas and $. ​