I have a '99 runner and since I got it five months ago, I've done a ton of mods and can't figure out if one or some have contributed to loss of power on the freeway. When it was stock w/ 15" wheels, the prior owner said he could cruise at 90 mph on the freeway.

Since I've gotten it, I've put 16x8 wheels w/ 265/75/16 tires, and a 3-inch lift. I have not upgraded the gears, and have installed a K&N FIPK and a magnaflow muffler. Both these mods gave me faster throttle response vs. stock. When I'm on the freeway, I can go 90 mph if the freeway is level but as soon as it hits an upward slope, the truck just slows down. I've even opened her up but nothing but louder noise at the same speed. I know that the rims and tires with the lift will kill some top-end but is this normal? I've also done full blown maintenance on the truck (smoother shifting for the tranny and more throttle response at low-ends), but nothing to improve the top-end.

I'm not supporting speeding over the limit but just want to know if this is normal for all the other 3rd gens out there. Any thoughts?

 

my runner has never been able to keep 90 while going up a hill and ive got a 97 3.4 with deckplate mod, and trd exhaust. on flat it can easily but i dont think our six cylinders can handle higher speeds up a hill at all. and wind also slows me down A LOT and sometimes i can barely go 75 on flat freeway with a strong headwind. i dont know if your small increase in tire size makes much of a difference. 3rd gen 4runners are slow. thats why i dream of the supercharger

 

Have you taken into account the speedometer change since your tire and wheel swap? With an increased rolling diameter, the speedometer is now reading less than it should. Therefore your actual speed might be much higher than you think, requiring more power to keep that speed. Know what I mean?

Proper gearing makes a huge difference. I must say, once I went to 4.30's and the supercharger (properly tuned) my rig just flies up the hills. Try 6000ft fully loaded, up a hill, 80MPH, 5th gear - no problem (with power to spare).

 

I can cruise fine at 80 up most slopes but that can easily drop to 65 on steeper grades and I'm fine with that.

 

With all of those mods you've done its very reasonable to assume that they will cause a loss in power...I have never gone faster than 85 in my Runner and I've never had a problem keeping that speed even on most of the hills around here. It stays pretty flat here so I've never really had a big problem keeping the speed constant.

Fink

 

actually, when i upgraded to 265/75s, it made my speedometer dead-on accurate. i know thanks to my gps.

i can go over 90, but on an incline i have to push it if i wanted to creep back over 90.

i stay well under that now, never really above 85.

 

Thanks for the replies.

A couple of things to add: I'm assuming a 5 mph increase than the speedo says because of the rim/tire upsizing. When I mean incline, I mean slight incline. I live in Los Angeles, and most freeways in different areas will have slight inclines.

The reason for the post is the drop off in speed is dramatic. I can go 90 but with an incline, can barely keep 70 mph. As soon as the freeway levels out, 90 pretty easy. I'm not a speed demon but just noticed this recently and have tried to see if it's the truck or not. From my limited experience with the truck, it just seems to struggle on the regular inclines. With steep inclines, forget about it...

 

Anything that would have added weight to the rig? Spare tire, the weight of the new tires...yada yada...system in back? Anything like that and you'd be amazed at the difference it makes.

Fink

 

bro... I know what you mean... When I had the 265/75/16 revos even before any lift... I would have a hard time staying at 80 up an incline... When I went to Vegas... Those mountains were killer.... I floored the sucker just to keep it at 75.... Now with the 295's... I need to get blown already.....

 

Hmm...

Fink

 

It's weird because even at WOT, the engine gets louder but the mph go no where on inclines. I wouldn't even try the Vegas trip with what I've seen. My 4 cylinder Honda Accord would fly up those hills (to Vegas) as long as I had a decent start. Maybe it is time for a supercharger. Don't get me wrong; I love the truck and it's really fun to drive. I just wish it had more power, especially for the gas it eats...

 

prepare to eat more gas! I know what you mean though. Even in the flats of VA It was hard for me to keep up with filthyrich in the mountains. He was easily doing 75 up the mt...and i was flooring it to keep it at 75. Meh, i know i dont have a racecar. Now im thinking about regearing

 

It all about the gears! I can cruise at 85-90 no problem in my truck. My motor has some basic mods on it, but nothing compares to the power increase of regearing.

 

Well technically there is absolutely no power increase with regearing, but we know what you meant

I find it kind of weird what you are all saying about 3rg gen's. I really never have problems with my truck unless the hills/mountains are quite substantial. I very often drive up and down large mountains and so long as Im in 4th gear I can keep any speed I want. In 5th my truck will do well as long as the hill aint to bad; especially at 80mph my rpms are up enough (5sp, 4.30) to haul me pretty well and even have a little power to spare.

This is a 3vz w/amsoil and deckplate.

 

i have no lift and the same size tires on mine and have no problem on hills. i can go over about 3000' in 3/4 mi (the conejo grade for those that know it) in cruise control at 80 and it usually only shifts out of overdrive. i can go up it at 95 w/o a problem and power to spare. i did once right after the fipk install to road test.

 

I would be willing to be money that gearing is your problem since the original tire size is 225/75-15 which is a @28 inch tire diameter and if your new size is 265/75-16 then those are @32 inch tire diameter which adds up to @15% difference in diameter and will most definately change engine RPM at a given speed. Basically you took the engine out of its optimal operating range, not to mention the new tires also have more inertia to them which will slightly exacerbate the situation as well. I bet if you regeared the power you miss would come back in spades. Yes, the speedometer will be off too.

The biggest difference is if the truck originally came with 15" rims, then gearing will not be as low as those that came standard with 16" rims. Even a 2.4L can feel very peppy with proper gearing. The more load you put on the engine (such as on inclines) the more torque is critical and the torque applied to the rear wheels is a direct relation to the torque band of the engine. If you change the gearing in any way (via tire size, 3rd, tranny, etc) you need to be sure to compensate for it or you would see problems on hills where engine load is at its maximum. This is also why people with S/C's hear the ping most on big inclines.

 

Great post. I thought the rim size was just an upgrade depending on the package you selected, and thought all 3rd gens were geared the same way. Is this not true?

If it's not true, I get what you're saying. ErikJeanna works around me and a regear for him would be $500 with gears and install locally. This doesn't seem as bad comparing the costs of a supercharger. My only concern is that I do the regearing and then it doesn't work, or worse, causes more problems. I hate people working on my truck that I don't know, and a regear would be something no one I know can do.

 

No, not all 3rd gens have the same gears. Hence the reason I swapped to 4.30's from 4.10's (mainly for the e-locker though).

Every single time I get on it in 1st/2nd/3rd gear I get a huge smile on my face and seriously laugh out loud. I am such a dork. Just this morning some old golfer-guy in a Cadillac CTS looked over at me and smirked as he heard my exhaust; we were side by side on a roll off the freeway. He floored it as we went down an open road. You should have seen the look on his face when I planted the pedal to the floor in 2nd and pulled away from him. It was priceless.

 

That's awesome. You said earlier that you have a s/c and you re-geared. I've read where bamachem got rid of the s/c because of the regearing. Did you just want to go balls out?

Also, since you guys are knowledgable and I'm too lazy too search, how do you find out what gears you have? I know that there are charts out there to tell you what to have, but what do I really have?

 

OK.....we'll let it slide, but we want video of a dusting like that next time!