RSR

Last PS -- it's the stock muffler that is the restriction from cat-back, not the piping. Just replacing the stock muffler will show you much benefit. Due to the physics of gasses (as in the exhaust gasses, not fuel/gasoline), the benefit of larger diameter exhaust is seen at the front end of the exhaust, not the back. You may get some benefits by increasing piping size for the crush bends over the rear axle -- but, *big but* -- you should be running mandrel bent anyway or if not running mandrel bent you really need to do the math and upsize your piping so that the crush bends are the same square inch flow area as the ideal mandrel bent piping (I think the ideal is 2.5, some say 2.25).

And keep it to the basics to fix your rig before you start adding a bunch of of aftermarket parts from vehicles that are not your original to identify and fix the engine's the problems first. Get it perfect in stock form, and then begin modding any engine component to add extra performance, instead of modding to try and get it to stock performance... In particular the AFM -- I wouldn't do that without fixing everything else first; it's a major component.

KtrainHurricane

RSR, while I do appreciate your very detailed, informative response, I stated before your long post that I am not even going to attempt to do much of anything in regards to this matter. ISR mod, sure I can handle that. Checking to see what types of plugs wires were put in my truck, fine. Other than that though, I am not even gonna try.

Suggestions/info I am asking about are things I can go to my mechanic with. Again, not sure what he will think if I walk in and ask, "can you check to see what my timing is set to, and then adjust it to 12*?" but that is something I will try.

In addition, it seemed like most of what you suggested is for getting more power. While that is appreciated and of concern to me, my bigger questions were about the mileage itself. I will most definitely sacrifice power and pick-up if it means I can get better MPGs. My question about the tires still stands...

KtrainHurricane

Not sure I really need to "fix" anything. The truck runs fine (with the exception of poor MPGs, which may be more "normal" than I originally thought). I have taken it in to my Toyota mechanic twice now for oil change/multi-point inspection and they've told me its fine both times; my family has been going to this mechanic for 20+ years and they've kept all of our Toyotas in tip-top shape.

P.S. - the hubs on my truck are the stock red Aisin ones, which are manual.

RSR

Your description of power and fuel economy does not sound normal.

If you want to fix your engine, you have to do some work to actually figure out what's wrong. Identifying issues I noted only requires some time, your vision, and a couple of basic tools. On a 20 year old engine/rig, it's doubtful that it's gone through the complete FSM inspection procedures since it first came off the factory line (like the valve adjustment, it's tedious and expensive to have your mechanic do, and only necessary and justifiable by the mechanic when they are told by you the symptoms of whatever is wrong; but on 25 year old vehicles stuff fails with no check engine light and reduced fuel economy and power are the only things that tell you something is wrong and needs investigate) -- you can either pay your mechanic a half to full day to check everything per the FSM, or do it yourself. My suggestion was for the latter as the troubleshooting on my list is, for the most part, easily accomplished with little to no mechanical expertise/special skills needed.

And if you don't want to actually have to do any work, I'm not quite sure why you're wasting folks' time on a DIY forum.

Regardless, here are my top 6 recommendation for things that will improve your fuel economy irregardless of anything else that might be wrong with your engine:
1. Replace air filter with Toyota OEM or Wix. You can squeeze it in by just undoing clamps, but might decide to use a screwdriver so you can remove intake hoses to fully lift up top cover.
2. Set timing to 12-12.5 btdc. A 15 minute job requiring a timing light, a torque wrench, and a socket set.
3. Redline intake cleaner in a full tank of gas. Run to empty. On start of next tank run 2 cans of seafoam spray through your throttle body or 1 can of amsoil intake cleaner. Buy and pour. Buy and spray.
4. Manual hubs on front. Go with Toyota Aisin (have to buy used), not Warn. Your mechanic will probably need to install. Some new gaskets are needed from Toyota too. That's it.
5. Complete exhaust. Thorley headers (allow you to keep emissions components) and Y Pipe, new O2 sensor, LC Engineering Y pipe/collector back exhaust, Magnaflow high flow cat. Buy and have your mechanic/exhaust shop install WITH FLANGES! Flanges are important. Not just weld. Weld w/ flanges.
6. Replace all driveline fluids and ensure all lubrication is applied as is necessary. Synthetic fluids preferred. Easily do this yourself with a socket set, purchased fluids and a drain pan or pay your mechanic. A grease gun or two with appropriate grease canisters works for driveline zerks.

And for standard maintenance, you should really adjust your valves and replace your PCV valve. And when they have the plenum off to do these, they can also inspect your vacuum and coolant hoses for wear and tear. And also check plastic components like the TVV of your engine that may have failed affecting vacauum, sensors, etc.

KtrainHurricane

Don't think I am "wasting" anyone's time here, especially since I've made it clear that I won't be doing the work myself...and it's not so much that I'm too lazy to do it as it is that I have NO experience or knowledge whatsoever, a full time job, and this truck as my only vehicle. It doesn't make much sense for me to go in and start learning how to be a mechanic on my DD.

I am just asking for some common things that I might not have thought of - the exhaust recommendation was a great one I think, and I will definitely be doing that in the near future. Adjust timing is something I will ask my mechanic about, as well as looking into the FPR, because someone suggested that in another thread.

Gamefreakgc

I think I misunderstood his post, I am also against K&N's "Cold Air Intake" that sits in the engine bay. Complete waste of money. I was referring to replacing the paper filter with a K&N filter in the airbox (you can also remove the "spoiler" that sits behind the headlight) to allow more air in. That alone gave better throttle response when I first got my truck. Didn't increase MPG that much (very slight) but at least it actually had some torque in lower RPM's.

KtrainHurricane,

We are by no means saying that your mechanic does not do a good job. I'm sure he's an honest guy and knows his stuff. What we are saying is that a mechanic cannot know everything about your truck, too many things are model specific. My truck was inspected when I got it and ran ok. Bad gas mileage, poor idle but ran just fine. Turns out all of the following was "broken" and neither the mechanic nor I knew it yet:

• Bad spark plugs
• #3 Exhaust valve stuck open - 10 psi (should be 170)
• Broken ECT Sesnor
• Broken TPS sensor
• Broken Cold Start Injector Switch
• Bad cap and rotor
• Bad battery
• Vacuum leaks - several hoses were cracked in half
• Bad Oxygen sensor
• Failing distributor

No mechanic would find all of these, I just knew it wasn't running as well as it should. I got to a shop when I'm really stumped with a mechanic that has a Pickup with a 22RE and he's a great help, but even he misses things.

Also, we're not suggesting you do all these things in the next week. I did all these repairs over a 2 year period! I also work full-time, drive this truck to work every day, and am newly married, so let's just say I have other priorities that come first! None the less, it can be done in increments.

I totally agree with RSR on waiting to "fix" the truck up first, then look to modify components that you want to work better.

RSR

Hurricane -- my comment to wasting folks' time is 2 fold, and not entirely directed to you. Yotatech is at its core a Toyota enthusiast forum. To get the most out of your old yota, you have to actually put personal time into learning about your vehicle from the FSM and these boards, and then figure out how/when/where/why your truck differs from what it should be. Others are here to help you with that, but you obviously have little interest in doing that. Secondly, multiple new threads have been/are being created that have already been addressed in far more detail before what's happening to you right now. Modern search engines are great things, but you still have to dig a little to find stuff. I was in high school just as the searchable internet really came into its own era, but I still needed to search a dozen engines and go through 20 or so pages of results to find what I was looking looking for. The same thing applies on these boards -- you have to actually dig. Yes, not searching saves you time, but it also just leaves you with significantly less knowledge and wastes other folks' time who have already covered this months or even years ago. I still search these boards -- use a google site search not the search toolbar btw -- rather than creating new threads as that's the single best way to get answers. And then ask questions to existing threads if something's not clear (it raises the thread to the top of active threads), and only create a new thread if something is NEW and UNIQUE. More often than not, a small investment in time searching will answer your questions without needing to add anything to the boards, except for maybe some pictures that weren't present in the original solution...

RSR

The dry flow filters K&N makes are the AEMs. They have a drop in for the 3vze as well. http://www.aempower.com/

Though drop ins are better than cone, I still disagree with removing the deflector however. Air follows the path of least resistance. And without that deflector collecting air from around your drivers headlight, air will be drawn in from the engine compartment at all speeds, but especially more at low speeds when you really want cold air for maximum power/torque.

EDIT: AEM's are cone only. It's AFE that makes the drop in dry flow/high flow filter: I do not know how clean it keeps your engine, but fyi.

However, the flow benefits are questionable, while increased dirt in your intake is certain: http://www.bobistheoilguy.com/forums...Number=1595175

RSR

Whoops, forgot about the S&B filter. The one I was originally thinking of and the only one I'd consider. The research: http://www.sbfilters.com/Filter-Types

This is the one for the 3vze: http://www.sbfilters.com/Stock-Perfo...tton-Cleanable

Bob's experts say that paper flow well enough for everything except forced induction: http://www.bobistheoilguy.com/forums...Number=1595175

Which goes back to the making sure your filter is actually filtering out the dust, dirt and other crap that prematurely wears out your engine...

KtrainHurricane

FWIW, I was asking about my gears and tire size because according to this gear ratio and tire size calculator I found online (http://www.alloyusa.com/gear-ratio-calculator), 31" tires with my 4.56 gears yield "best performance but at the expensive of MPG."

Using the same chart, it says that if I went all the way up to 33" tires I would be closer to a "good balance," but still leaning towards the "power" side of it rather than the fuel efficiency side...

RSR

You're reading that chart wrong. Anytime your tire size goes up, your MPGs/efficiency will suffer. They're essentially saying this is the minimum efficiency gearing they'd recommend that still has necessary power, this is the mid point gearing between their recommended efficiency/power, and this is the power gearing they'd recommend that is also efficient. None are performance centered, all are basically their idea of optimizations relative to Jeeps' respective engine power bands and tranny gearing I think. So to your point above, your MPGs won't improve with bigger tires as you seem to be stating; rather, lower gearing irrespective of tire size is more efficient, and their efficiency formula makes larger gears calculate as the ideal efficient gearing at larger tire sizes while the same gearing is a power posture for smaller tire sizes.

Think of diff gearing like riding a 5 speed bike. Low gears are way easier to peddle but lack the power. High gears are harder to peddle but have more power. So with lower gearing you get better mpgs (as your engine has to work less hard to turn the wheels) but at the sacrifice of power -- it'll take you longer to accelerate for instance but keeping the wheels turning is easier, from a stop low gearing will force you to drive like your grandpa. With higher gearing, your engine has to work harder to turn the wheels (decreasing mpg) but that additional work also puts out more power -- you accelerate faster but your engine also has to work harder to keep the wheels turning once at speed, higher gearing will allow you to accelerate from a stop with much greater seat of pants power. But there are tradeoffs at high end efficiency/rpms/etc with gearing for low end power, so you need to do your math.

I find that chart's recommendations to be Jeep specific and definitely lower than what most of us on these boards would tell you -- I know Jeeps are weak, but by those recommendations, they'd be completely heartless...

You want tires and diff gearing customized to both your rigs's power band and to ensure that your performance is at least equivalent to factory base specs (our engine's on both 3vze and 22re can't afford to lose much in the way of power and still do what we want them too...).
Here are my two favorite gearing resources.
For our trucks (and I think his tire size/gearing ratios recommendations are spot on): http://www.brian894x4.com/Gearratiosanddiffs.html
And you can customize this one to your truck and make sure you're generating power where you need it to based upon tire size, gearing, engine, and your respective transmission: http://www.grimmjeeper.com/gears.html

But again,we're beating a dead horse here.


Tire size and gearing are probably the single most covered item on these boards. Search!

KtrainHurricane

Yes, but you did not address the energy (fuel) it would take for me to pedal that bike at a constant speed. While the lower gears will take less energy to get going from a stop, once I am at ANY decent "cruising speed" I will get tired much faster staying in those low gears as opposed to using higher gears. It would take me a million rotations per minute to stay at speed "X" in low gear while it would only take me 10 rotations per minute if in a higher gear, thus using less energy....no?

RSR

I'm not sure, but I think you have it backwards.

Higher gear numbers (what I'm referring to as high above) is actually considered low gearing in technical parlance. Lower gear numbers (what I'm referring to as low above) is actually considered high gearing.

The correct answer was addressed in my original post that you quoted, but maybe it wasn't clear:
lower gear #s, high gearing higher gear #s, lower gearing The differential gear numbers are the number of times the driveshaft must turn to turn the axle once. So at high speeds with high gear #s, low gearing your engine has to turn the driveshaft a greater number of times, requiring more gas and higher engine RPMs, than is truly necessary to stay at that speed. Low gear #s, high gearing is more efficient because it allows your engine to put in only the energy that's required to maintain that momentum. Power required to maintain a speed is essentially a function of overcoming drag and friction, so it's a lot less than power required to get to a given speed. Basic physics.
You should also look at the differential gear #s as multipliers of torque, each increase in gear number multiplying torque by that number.

There's also a lot of interesting differential research that shows that high gear #s, low gearing have little to no effect on MPG with city driving and only marginal affects on fuel efficiency at highway speed. So if you're looking for better MPGs you should really look elsewhere than gearing and making your truck even more heartless -- I'm pretty sure you're the one complaining about highway merges already being a safety hazard due to a lack of power, so not sure why you would be putting fuel efficiency before power when you already have a very obvious safety issue due to a lack of power.

So back to improving fuel efficiency, you should once again revisit the standard maintenance, upkeep, and performance tweaks you can and should do to your truck that will improve fuel efficiency without question and at a much greater rate than you can by putting in lower gears and cutting your truck's balls off -- following our advice will add power and improve MPGs without jeopardizing your safety and the safety of others trying to avoid you... An under powered vehicle is dangerous, and one of the reasons why I always put safety and performance before fuel efficiency when buying vehicles -- something you have to do these days even with brandnew vehicles such as turbo or straight 4s in SUVs that really need a minimum of 6 cylinder engines to have the power/displacement necessary to accelerate and maneuver out of harms way (and often the engine downgrade only results in a measly 2-3 mpg gain on the highway with no city mpg improvement, while also running a hot turbo that will cause the engine to fail much more quickly than a non-turboed 6 would...).

Basically, the whole gearing thread goes back to our original point that you need to get your truck working properly in stock form before you start "tweaking" and creating a whole other host of problems that will only lead to you selling the truck when it doesn't do what you thought it would, ultimately just forcing its next owner to have to clean up a mess. The tedious, non-sexy, boring maintenance-- not short cuts -- will be what gets you to where you want to be.

RSR

Made some edits above as I think we might have been talking apples to oranges, but should be clarified.

The research on gearing and MPGs -- basically, below 60 mph, it's driving habits not gearing that affect MPGs and the affect above 60mph is basically a 3/4 (0.75) mile per gallon increase for each 1x multiple (so going from a 3.5 to 4.5 gear ratio you increase your 60+ mpg by less than 1 mpg at the cost of a significant loss of power up to 60mph -- roughly a 30% decrease in torque/power for a less than 5% increase in highway MPGs exclusive to gearing changes [power above 60mph is a function of horsepower, not torque and not gearing]):
http://www.propickupmag.com/understanding-axle-ratios/

Also since we're talking about differentials, a synthetic gear oil with higher cold viscosity (just one of our many recommendations that would surely improve your MPG -- and performance -- would probably make as big or bigger difference in MPGs than going with a lower gearing). Amsoil is either the best or near the best in options btw (I think our trucks call for 80w in one and 75w in the other diff, but it's the second number you need to be concerned w/ and they're both 90, so Amsoil's 75w90 Severe Gear is the way to go -- I also recommend going w/ stronger power magnetic drain plugs while you're in there, I have Gold Plugs):
http://www.lastgreatroadtrip.com/wp-...comparison.pdf

This is a great resource too talking about the relationship of drag and speed: http://www.trucktestdigest.com/axle%20ratios.htm

KtrainHurricane

Putting the "how to improve my fuel efficiency" aside and ONLY looking at gearing and tires - my point was that once you reach a certain speed, with too short of gears/too small of tires, the engine will be running at higher RPMs than with taller gears or larger tires...at least this is my understanding, and the reason I am asking about it (because I am still partially confused/uncertain).

Hop on a bicycle in the lowest gear - "quickest," for lack of a better term - and pedal to maintain a constant speed of 15 MPH; you will be dead in 3 minutes. Now do the same thing in the tallest gear; while it may be harder to get going, after the first 10 seconds or so (which is about how long it would take you to pedal that bike to 15 MPH) I could go on for 3 hours without getting tired, because once I have momentum the bike is much easier to keep moving at a constant speed with those taller gears.

I am under the impression that tires work in the same way these gears on a bicycle do - just like tires on drag cars have an impact on what they top out at in the 1/4 mile. When fast cars (10s) run, they need a minimum tire height to avoid "running out" of gear and topping out before the 1/4 mile run is over...or so I have read.

Using these two examples, I come to the conclusion that by going to a taller tire it may require more work for the engine to get going at first, but once I am at a constant speed it should cruise easier, thus using less fuel. Is this absolutely wrong?

aztoyman

How accurate is your mileage calculations? If your speedo is off because of a gearing-tire size mismatch you won't really know.

Have you tried using GPS to make sure your speedo is accurate?

KtrainHurricane

Yes...but I do not remember exactly what the difference is. I do know that at 70 MPH (according to my speedo) the GPS read slightly differently; and I believe the GPS read faster. Maybe by 2 MPH or so.

RSR

You also have to calculate for any difference in tire size for mpg calculations too...

To your tire analogy, what you are failing to take into consideration is how your tranny already is changing gears to maximize efficiency at different speeds. You're not in one speed forever like on a bike. With differentials, you're changing the number of rotations of your drive shaft it takes to turn your wheels. This is an effect in combination w/ your tranny gearing... Your differentials change power output across all speeds, but the tranny has far more affect than gearing on your engine RPMs as you can see when it shifts.
Did you red the Pickup Pro Mag article? It explains all of this and more in a very newbie friendly way and should answer all of your questions. You've gotta put in some work to understand KH... Sorry, can't spoon feed it more than I already have.

Also with gearing, one thing you need to remember that when you change tire size from stock, your effective gearing changes as well. For instance, the stock tires on our pickups are 225x75r15 (28.29" diameter). I have the 31x10.5r15 (30.98" diameter) tire package included swapping diffs to factory 4.88 gears. But nothing else changed in tranny, etc, except for those diffs, so my effective gearing did change as well. When calculated off of new tire size w/ 4.88s, my new effective gearing is 4.46 to 1. W/ 31" tires, to have 4.88 effective gearing, I'd need to have a 5.34 gear ratio... Going from 31" tires w/ 4.88 diffs to stock 225x75r15 tires would make my effective ratio 5.35 to 1... Etc

I like this tire size comparison tool: http://www.tacomaworld.com/forum/tir...r15-31-10.5r15
*It also has speedometer, revolution, and other differences...

And this is a good effective gear calculator that tells you what new gearing you need when changing tire sizes to keep your factory gearing ratios as well as high gearing and low gearing recommendations too : http://www.4lo.com/calc/geartire.php

Before you change your gearing and tire size, just make sure you have a solid understanding of what you're doing and how everything is connected.

KtrainHurricane

Thought I would throw in this interesting piece of information -

I recently had my transmission rebuilt, as I had overheating/slipping issues with it. This itself didn't yield any significant MPG improvement; however, I also got new wheels and tires for the truck. They are the factory option Enkei 15" alloys that were available on 4Runners and T100s. I traded them, and they have BFG Radial Long Trail (same as my old tires) with about 40%-50% tread left (my old ones had 0%-5%). They are also 225/70R15, as opposed to my old 235/70R15 size.

Since installing the new wheels, I have already gained a significant amount of mileage per tank - I previously maxed out at ~210 miles per tank; I am now at ~200 miles with over 1/4 tank still left. I am very happy!

Gamefreakgc

I hate being the bearer of bad news, but I too was under this assumption with my tires and found out otherwise.

If you have an SR5, they came with 31" tires, much like the Taco's after them. Not all models, but the SR5's did. I currently have 225/75 R15's, what the "books" say the truck should have. Here's my discovery: https://www.yotatech.com/forums/f116...nfused-272221/

Basically, if you drop lower than 31's your tires are spinning more per mile and giving a false reading. Your MPH's and MPG's are inflated by 9%. For example, a recent road trip was 91 miles, and my odometer read 100 by the end. GPS says 63 MPG, speedometer reads 70. Use a smartphone or GPS that reads MPH and you'll see what I mean.