I posted this in the tire and wheels section, but it is a Tuner question also, please take a look and tell me your opinion.

http://www.f150online.com/forums/sho...hreadid=146830

thanks in advance

 

Hi rbraughn,

No wonder you were confused! That is certainly a fair topic for the Computer Chips section, no problem...............

Preferably, you enter the measured actual height of the tire after it's mounted on the rim and inflated to normal pressure.

You can do that with it on the vehicle - yes, the vehicle's weight will cause the contact patch section of the tire to flatten out a bit, but that does not change the diameter of the tire or it's revs per mile spec - any vehicle is going to cause it's tire's contact patches to flatten out a bit. It won't have much effect on the actual installed tire height, certainly not 1"+, etc., at 32 PSI & on up, generally speaking.

The way you did it, by entering in the measured tire height as installed on your vehicle, generally works just fine - and many of today's tires are *not* the actual height they are rated at, especially in the taller tires.

If you get a chance to check your vehicle's speedo with a known accurate source, you can follow up and make any adjustment as required, simply by altering the height data you enter into the Micro Tuner in 1/4" increments, that's it's resolution capability - until you *nail* it. Otherwise, what you did is generally fine, and is usually as close as the factory speedometer calibration.

Good question, & good luck - let us know the results if you ever get to do a comparison with a known accurate source and need to make any adjustments to your measured-as-installed tire height speedo calibration, we're data hounds around here!

 

Thanks Mike !

I will either try comparing it to a handheld GPS reading, or get one of my buddies to zap me with their radar gun while on duty to see how close I am.

Thanks again

 

Hi R,

You're very welcome - I had no idea you are on the job (be safe out there, please!!)

That will make it a lot easier to get a good accurate read on your speedo calibration, and allow you to get it dialed in to the nth degree - excellent!

 

On the Job...

No, Not me....I am a civilian employee (19 years) of a Police Dept. About the only danger I have is getting Carpal Tunnel working on all these computers, or falling out of my chair if I fall asleep


I appreciate your concern though

 

Understood - though you may not exactly be "on the job," what you're doing contributes something valuable to the cause - computers are critical to law enforcement!

Good luck with the carpal....

 

Mike, I have essentially the same question. I finally got a chance to play with the MicroTuner this evening. Saved the stock program, no problem.

But I was stumped when it came time to enter the tire size, since it measures to rougly 30.5 inches, but the tire calculators for 265/70R17 indicate 31.6". That's an inch difference!

What's the standard height of the 265/70R17 Yokohama Geolanders on a 2001 King Ranch SCrew 4x4 with standard rims?

I had to return to the stock program, since I figured "stock" probably wasn't the right answer, and I wasn't sure what to use.

I'll be experimenting with the Performance, Tow-Perf, and 87 Octane settings. I was able to locate 91 octane fuel for the Perf and Tow-Perf settings, though 93 is much more commmon...many of the stations don't have 91...assume that would do.

 

Hi TLeBlanc,

First - forget what the P-metric size ratings say the tire height *should* be, that's the myth of P-metric sizing - that whole deal was supposed to give us a level playing field and consistent tire sizing (for example, all P265/60/16's are supposed to be the same height & circumference regardless of brand, model, manufacturer, etc.), but it just hasn't in many cases.

Ideally (and we haven't discussed this very much, but there was a poster who made this excellent point the other day in another thread), measure this with the tire mounted on the wheel and inflated to normal pressure, but NOT installed on the vehicle. Now realistically, usually most people don't often get a chance to do that, other than perhaps when new tires are being installed. The vehicle's weight will flatten the contact patch a bit, that is true - one technique I like when using the 1715 Micro Tuner is to enter the measured height and then add 1/2" to offset the compression of the contact patch, and then dial it in from there. (Most factory F-series speedo calibrations are about 2 mph off at 70 mph to begin with.) You have resolution down to 1/4" intervals in the Micro Tuner, so use it - keep playing with it until you get it dialed in, don't just enter 31.5" (as close as you can get to 31.6") if it actually measures 30.5", enter what it actually is, plus 1/2" if your measurement is as installed on the vehicle. Measure one of the *rear* tires when measuring tire height with the the wheels mounted on the vehicle, as they have less compression of the contact patch out back due to the engine being up front (typical front-engine vehicle weight distribution).

Next..............

You've got a beautiful, very expensive top-of-the-line F-150 there, a King Ranch - feed it accordingly is our advice.

All kidding aside, we recommend NOT using only 91 octane when 93 octane is available in the same market - the 91 is not only 2 points less octane, but is also usually of a lower BTU content as well as having fewer and lower quality detergent additives. It's their "cheap" version of premium gas, which I call a "semi-premium." Use the good stuff and you'll get better fuel mileage, as well as more power - and fewer combustion chamber deposits as the engine accumulates miles. Sure, you can probably "get away" with using that 91, but I'd never do it if I had a choice of 93, and in your case, most of what you have out there is 93, the 91 is atypical - so it's not a real "premium" gas in that market.

Remember, you can have 2 fuels that each have *identical* octane numbers, but one having a lower energy content can actually cause detonation even though the base octane number is the same - and chances are you won't ever even *hear* any detonation, the knock sensor reacts too fast, retarding the timing (and reducing power). This is one of the primary reasons we advise not using Exxon, for example, which is "reformulated" year-round in the US (which causes a lower BTU content) - they started that about 4-5 years ago. I hate saying not to use Exxon, as having worked in the oil patch for a few years and having been in virtually every refinery & tank farm that existed in the 48 states as of the mid-1980's or so, Exxon's refineries and tank farms were generally among the very cleanest & usually among the safer operations in the US as well - credit where credit is due. (I know, this always makes people scream when I say that, thinking Exxon Valdez, but it's true - Exxon generally spends a LOT more money than required on cleanliness & safety in their operations, or at least, they always did during my years of seeing their operations.)

OK, now for the inevitable "but Mike, what about all the West Coast owners who can only get 91 octane?"

Out west, 91 is their true premium gas in those markets (and is in many locations west of about Texas), so it's actually the *best* fuel available to them - where it's *not* the best fuel available in your area, you just want to use it because it's cheaper (NEVER buy gas based on price). Using California's 91 octane premiums is not like others using 91 in markets that have 93, even though the octane ratings are reported to be the same - think energy content, energy content, energy content.

With our performance tuning for premium gasoline, use all the octane you have access to up to 95 - anything more than 95 octane is a waste (unless we specifically tune your engine for it), and you start to make less power because as octane increases, it takes longer to initiate the combustion event in terms of degrees of crankshaft rotation, and you reach a point where the motor just doesn't have enough time to burn enough of the ultra-high octane mixture, and at that point, power and fuel mileage actually *decrease* - this is why your owner's manual tells you to use 87 and NOT use premium, simply because from the factory, these F-150 engines aren't tuned for it, and that can raise emissions, lower power and reduce fuel mileage.

Many people (quite naturally) think gas is gas is gas - while there are some cases in which that is close to true, kinda-sorta, most of the time it's not - there are significant variances in energy content & detergent additives. "Cheap" gas isn't cheaper because the retailer (gas station owner) is giving up his profit, or because it's being pumped at Sam's Club, or Costco, etc. It's cheaper because they're paying less for it on the wholesale level and getting less in return, thus you get less - I.E., it's cheaper because it has a lower BTU content and lower quality and quantity of detergent additives.

Over the life of an engine, cheaper fuels generally cause increased combustion chamber deposits which cause an engine's "appetite" for octane to increase over it's lifespan, as those deposits displace air volume, thus raising the static compression ratio - as well as contributing to a dirtier fuel delivery system from end to end, stuff that fuel filters don't remove.

OK, my standard patented fuel-quality diatribe is over & I'm climbing down off my tiresome soapbox - thanks for your patience.

 

Apology? After all that good info? I should think not.<g>

I'll measure the rear tires...that's a very good suggestion, since I did measure the front. Adding 1/2" sounds like a reasonable compromise to compensate for the "at rest" compression of the tire. I have no idea how I'd "calibrate" my speedo settings unless I could find a speed trap display that I knew was right.<g>

Good to hear that 93 octane is "preferred" over 91, for two reasons. One, 93 is MUCH more common here, 91 was actually hard to find....then I re-read the manual for the 4th time and noticed it says "at least" 91 octane, which makes sense.

I've run 93 in my other vehicles for years, generally preferring Amoco and Shell, since it seemed to me that they were the only companies delivering "clean" premium fuels from their own refinieries and distribution facilities. Don't know if that's the case now. I usually run my vehicles for 10 years or more, with well over 100k miles, without engine problems. So it does seem like a good idea to continue.

I'll measure the rear tires, both on the ground and with one jacked up clear, just to satisfy my curiosity. I'll post back what I "find" and what I decide to use with the tuner to set it up for Performance. I'll be switching back and forth between Perf and Tow-Perf, as needed, using Tow-Perf when I'll be pulling the trailer about once a month or so.

The truck seemed to have no difficulty pulling the trailer, though it was a bit sluggish, as would be expected. The shift slippage and loss of power were definitely more noticeable.

The Prodigy brake controller is a VERY good product, worked well with minimal adjustment. Still have to fine-tune the bracket setup before I can use it, had to use beige velcro in the "standard" position this time, which worked...but the curved surface will require some "adjustment" to achieve a really good mounting using that technique in that area. But I won't have to drill any holes and the pocket would be easily removable when not in use, which is most of the time.

Thanks for all of the great feedback and info, Mike. Keep it comin'.

 

Hi TLeBlanc,

I agree, over the years I too have loved Amoco & Shell. Shell still works very well here in the East (and in some places out west as well, though not quite as consistently out there), but unfortunately, Amoco is many times not the fuel it used to be ever since BP (British Petroleum) bought them out. Traditionally, Amoco (Standard Oil) has been an excellent clean fuel with a nice high BTU content - one of my favorites. But BP has historically been just the opposite (what a dichotomy to merge, eh?) - dirty and low energy. Nowadays, it's a 50/50 proposition when filling up at the yellow & green logo BP stations that say "Amoco fuels" on the pumps, so we advise avoiding them now for the past couple of years since BP bought them out. I did recently come across an Amoco station in Lexington, Virginia that was still the good 'ole Amoco fuel, or perhaps I should say, my 17 PSI boost Lightning loved it. And there wasn't any BP name or logo or colors anywhere in sight, just the traditional red, white & blue of Amoco.

The bottom line is, use the best fuels and your engine will thank you for it, rewarding you with a nice long lifespan with less deposits & a cleaner fuel delivery system.

Excellent idea to jack up one side of the rear of the vehicle to take the tire measurement, and then do the measurement with the weight on the same rear tire to do the comparison (I'd probably want to stand on the back bumper to rock the vehicle up & down a few times after letting it back down off the jack, just to equalize the springs & weight distribution and do all that on level pavement - yeah, I'm ****).

I look forward to seeing what you find when you do those measurements both jacked up & on the pavement - and of course, you'll want to enter whatever you measured with it jacked up and no compression of the contact patch - I should have thought of doing that myself, D-oh!

Last - while it's not always easy to find one of those roadway construction radar speed signs, another option is to use *modern* GPS gear - preferably made from 2003 on up. We used to recommend people NOT use GPS for checking speedo calibration, but over the past 12-14 months, we're seeing the newer GPS gear doing a much better job - and I don't mean since NSA took the deliberate "skew" out of the "publicly accessible" GPS sat signals, I'm talking about post-that and with the more modern GPS consumer hardware - just a thought. There's always the technique of running along with a vehicle having a *known* to be accurate speedo and do the comparison that way, but then, so many speedos are a couple of mph off at 50-80 mph and up anyway. One other idea is to try comparing Odo readings with the relatively easy to find State Police calibration roadsigns, where they usually have anywhere from 2 to 5 miles of signs along the Interstate or highway they use at set intervals to do an Odo distance countdown.......good luck with that!

Talk to you soon,

 

OK... I got a full half inch "taller" reading on the rear tires than the front with them on the ground. The front was 30 1/2, the rear was 31. when I jacked the rear end up, cleared the ground, then just let it "kiss" the ground on the bottom, it measured 31 1/2 inches...pretty close to the "rated" 31.6.

I used the 31.5 in the tuner and set it up for Perf. I'll run this tank of 91, then switch to 93 for a couple to compare. In a few weeks I'll switch to the Tow-Perf and pull the trailer, for another comparison.

I like the old Amoco, used to run it almost exclusively, Shell was my alternate...for years. As you say, BP "ain't" the same.

Gotta' go...be back later...

 

Pretty interesting, Mike, that your "add a half inch" for the at rest contact patch compression was right on the mark. Also interesting that the front tires are compressed another half inch due to the extra weight up front. That explains the full inch difference from the rated diameter for my initial front tire measurements. I don't like loose ends...all tidied up now.<g>

I jacked up the whole back axle from under the differential, took both rear tires off the ground...did a quick measurement of both sides, then lowered the axle until the tires just "kissed" the ground. Measurement was the same, just easier from the ground up, no offset. The Yoko Geos 265/70R17, the "stock" size for the King Ranch SCrew 4x4, are 31.5" in diameter mounted and unloaded.

I ran the truck this evening when we went out to dinner after little league baseball practice. Definitely firmer shifts, but not at all unpleasant or harsh, just quick and solid, much better. Too early to tell much, but initial "feel" is much better than stock. Looking forward to trying with 93 octane Shell.

OK...now for that GPS thing... I assume you're talking about measureing "distance" over time using a GPS handheld? I'd like to hear more about how to do that...any recommendations on a newer GPS unit to buy?<g> One of the veteran leaders in our Scout Troop has a GPS unit, new one, a Garmin, don't know the model...pretty slick what it can do...watched him experimenting with it on a hike a few months back, he was learning how to use it.

Hmmm...don't recall seeing calibration roadsigns...must not know what I'm looking for. I've certainly seen the standard mile marker signs.

 

Hi T,

Glad to hear you went to all that effort to confirm my "half inch rule" when measuring the rear tires - this is exactly why I say to measure the rear tires and not the front tires - nice to see all of that independently documented! So the fronts compress a full inch, and the rears compress 1/2" when measured on the vehicle. The additional weight of the powertrain up front gives that extra half-inch of compression of the contact patch.

On the GPS gear, I'm probably the worst guy to ask, as I don't use it as until just the past 12-14 months it hasn't been accurate enough for my tastes - now I'm doing a lot of price shopping. There are others who know far more about that than I do.

Garmin seems to be a good (and very popular) brand overall, but it's still expensive - $1K for their nice units. With as little as I know about it, I'd probably rather use a DeLorme or something similar & just plug that into my laptop and spend less than 1/5th that amount and have a much bigger screen - but having the laptop open & running on the road on a long trip is a pain. Obviously I haven't decided what I'm going to do yet.

On the highway signs, no, I don't mean those standard milesticks - you'll know 'em if you see 'em, they'll say something about being a reference for official or police use, etc.