4 cylinder towing speed engine limit question

I have a 1999 gen 1 with 120k miles 2wd 5 lugger 14" tires with the 2.4L 4cylinder engine and automatic.

here is the question:

this is the first time I tried to pull my 17ft flatboat and single axle trailer that's 1000-1200 lbs total (and that's an over estimate im sure) including motor and all combinations of whatever stuff I throw in the boat. (500 lbs boat + 250 lbs motor + 250 lbs single axle flatboat trailer + 100 lbs ice chest and fishing junk in boat)

the truck seamed to be very underpowered and struggling with what I would call a very light load.

on the way fishing this morning (a/c off, heater on) and it took a little while but it got up to 70 mph and I set the cruise control and it held that speed and I didn't notice and downshifts or anything but it did struggle to get above 60 mph and took a good solid full minute to reach 70 with the pedal almost to the floor.

on the way home I had the a/c on, and it topped out at 65 mph and wouldn't go any higher (pedal to the floor) unless I turned off the OD and then it was turning 3500 rpms the whole time and you could tell it was straining to do it but it did get up top 70mph so I set the cruise control there and turned OD back on and it would slowly loose speed and couldnt hold a steady 70 mph speed with cruise on or it keeps constantly downshifting out of overdrive every 2 or 3 seconds and takes like 5 seconds to go back into overdrive. if I set cruise to 65 mph it shifts from 3rd gear to overdrive like ever 5 seconds and if I set cruise to 60 for it to finally hold a steady speed and stay in overdrive and not downshift anymore unless I get on an incline.

it wasn't a windy day and the roads were flat and level (no hills in Louisiana lol) and there are no issues causing drag from the truck or trailer, both roll very easy so at best all there would be is the air force creating some drag which should not be much. the way it is acting, this seams a lot weaker then it should be but I want to ask to confirm.

to add I have a slight hesitation in the truck when you just give it a little gas like if you want to go 1 or 2 mph faster it seams to hesitate and not want to go but with a little more pedal it goes just fine. its like from just above idle to 1/4 throttle is where it hesitates or when slowly accelerating when under load.

this is the first time I ever pulled the boat with it but without the boat it seams to have good power and can do 70 mph without any struggle at all.

truck has new NGK wires, NGK plugs, air filter, and the MAF sensor was taken out and cleaned with MAF cleaner. tranny was completely flushed and new synth fluid added and changed oil filter with synth engine oil.

I am not familiar with these 4 cylinder trucks so if that's how they are then im fine limiting it to 60 mph when towing but I just want to know if this is normal or some side effect of my hesitation issue not getting full power (which is what Im thinking it is) other then the hesitation under load or at very slow speed increase and rough idle that they all seam to have the engine runs great and relatively smooth.

 

If you are towing with that little engine DON'T USE OVERDRIVE!!! It is there for gas saving purposes only, you can only do damage by running hard in OD. That quick shifting in and out of overdrive is called hunting and it is the natural predator of Auto trannys, it builds heat and destroys tranny fluid leading to improper lubrication and ultimately destruction. I would advise not going 70MPH while towing unless the vehicle and driver are properly configured/informed. Most will advise against flushing Taco trannys as well, they don't seem to respond well to it, a good ol drain and fill usually is better.

That is a good little motor, just don't expect it to break a land speed record with a load. Read the Tacoma towing bible here.

 

what he said^^^, your much better off letting the engine sing at 3k rpm than havin the tranny hunting for gears. Its a tiny motor(as far as trucks go) which is probably only rated at 130ish ponies and then with the auto tranny robbing even more ponies there's only so much the little fella can do. Leaving the a.c. Off might have helped a bit but probably not much.

 

ok, so your saying its acting normal and it just doesn't really have any towing power, not even to tow 1000 lbs, I guess im learning some of its limits.

that's good to know then, ill just keep it at 60 mph max, that seams to be where it feels like it starts to run out of pulling power.

it was a short 40 mile round trip (20 there then fishing then 20 back) so it was really 2 short 20 mile trips in cool weather (60's-low 70's here) so im sure nothing got overheated so im sure I didn't hurt anything. While I tried to see where OD worked without down shifting, I just reduced speed enough to stop it from shifting and it only lasted a minute or maybe two at most.

the tranny flush was a dump and fill job, because the oil was just old and worn out, not because it was burnt or dark, it was just old. I flushed it myself, no pumps or machinery, I just flushed it by using the radiator cooler and pumped the whole system with new fluid not just the pan. I know about leaving it alone if the fluid is funky.

im still getting mentally used to a 4 cylinder after having v8 for 30 years I have to learn the feel of it and what it cant do. I haven't had a 4 cylinder since I was in high school.

now I just gotta try and see if I can figure out what that hesitation thing is

 

The 4cyl only seems underpowered because it is. I switch back and forth between the taco and my 350hp mustang. It takes some getting ised to. If youre going to tow a lot i would regear. If every now and then youll just have to get used to it.

 

well ill be towing that same boat probably close to half the miles I put on the truck

what is involved in re-gearing the rear end?

how much would it feel different in non towing driving? will it rev higher and burn more gas?

how would I find out what gears I have now and what I should switch to?

wouldn't that throw off my speedometer gear in tranny?

and whats it cost to do all that?

remember this is used 50/50 as a grampa goes to the store truck and truck pulling the boat on 150 mile round trips going fishing

 

There's a lot involved in regearing from what I understand. It'll be costly. You will rev higher and burn more gas. You'd have more low end power because it takes more turns of the driveshaft to turn the wheels. It would throw off your speedo.

I personally think that it's more beneficial for you to either get a bigger truck or just turn overdrive off and reduce your speed.

 

me too, i have no money (fixed income) and i sure don't want to change anything unless its absolutely necessary.

I want good mpg and going slower is no big deal to me. where I go fishing down south its mostly 70 mph speed limit 70% of the way there for about 60 miles so I guess I will be getting passed up a lot lol.

obviously i wont be able to go passing up any slow tractors on the 40 mph roads either lol.


according to "the bible" speedytech7 linked to this is my rating:

The 2.4L I4 (available only in the 5 lug 2wd (non pre-runner) trucks)
142 hp @ 5,000 rpm
160 lb.-ft. @ 4,000 rpm
Max. Towing capacity 3,500 lbs.
Max. Tongue weight 350 lbs.

so based on that im only towing 1/3rd of the rating (1000 lbs. 100 lbs. tongue weight) and it struggles, i just thought it would be able to tow a flatboat at 70 mph is all.

 

Don't forget. Towing captivity depends a lot on what you can stop too. I could get lots of stuff going in my truck but the real question is could I stop it? The truck is also 15 years old too. Don't forget to factor that in!

 

well a trailer that I can easily push around in my driveway with one hand seams like that shouldn't act any different when connected to the truck. I just have a hard time understanding how it actually creates that much of a load to be pulled but obviously it does.

yes I understand stopping takes twice the effort as getting it going

I still have to find the cause of my hesitation issue because I think that is robbing me of a lot of my towing power too. the stumble or hesitation would be just the part being operated by the cruise control because its when your just barely increasing speeds.

 

Personally I would never use cruise control while towing anything.

 

3000 rpms isn't that much. My first several cars were four speeds and they all turned that or more going down the freeway. Even my 5 speed Honda CRX probably turned almost 3000 in 5th gear.

 

I recently bought a four-cylinder Tacoma that I will be towing with. I haven't towed with it yet but I have towed with other four-cylinder compact trucks. It's hard to know what you're feeling, but I agree with you that 1000 pounds shouldn't annihilate the truck's performance, so that hesitation might be having an impact on what you're feeling. If it feels like the engine just falls flat when you accelerate I would be thinking electrical; if the hesitation is milder I would lean toward fuel.

In the meantime definitely stay out of overdrive when towing, and consider taking roads where you can go slower. I like 55-60 mph when towing with a smaller and/or less powerful vehicle. The manual of my truck echoes this advice to avoid overdrive when towing, and Toyota says to stay at 65 mph or below.

 

I think the big factor here is the automatic trans. I have a '96 with the 2.4 and a spd manual and i have no problem towing 2000 lbs at 70. keep it around 60 mph and out of OD and you should be OK.

 

Or just trade the truck in for one with a better tow ability. The taco can do the job but its not the best tool for that particular job. I had 31s on a taco i just sold, has the same effect on axle ratio but in the bad direction. I put factory rubber on before i sold it, felt like it had 2 extra cylinders.

 

thanks for the help guys.

I like how the truck is the way it is. I bought it for the great gas mileage and will just have to adjust my driving to fit its ability, its just that im so shocked at how neutered it got with what I consider relatively no load at all.

If I had a regular boat going around 2500 lbs I don't know if the truck could even pull something like that the way it is acting now.

without the boat it has no problem doing 70-80 mph on freeways and it isn't winding up high rpms so it must be due to that hesitation thing it has but im at a loss to find it. as far as I know alternators don't engage and disengage a load on the engine so maybe I just have a weak battery or alternator that needs replacing.

I tried new plugs and wires, cleaned and then replaced the MAF sensor, throttle body and duct work to it was visually clean so I didn't take it off to clean it but I don't think cleaning it would change anything.

as for electrical, I don't have any CEL but I do notice when I turn on my headlights or hit the brakes, the idle slows a little but I assume its normal for these little trucks.

I guess I better replace the fuel filter but its a HUGE PITA to get to. if that doesn't solve it i'll pull the throttle body and strip it down to clean it.

I think I saw something about a faulty TPS can cause stumble on acceleration but I lost where it was and cant find it again, does anyone know if that's true or not?

I am on a fixed budget, money is VERY tight so i cant afford to be replacing parts that aren't bad.

 

Why replace the fuel pump? The problem is expectations of driving 70-80 in OD while towing.

 

sorry, it was a typo, I meant the fuel filter (I fixed it)

I don't expect to tow at 80mph in OD, I rarely if ever go over 70mph. I was saying I expected that with what I consider to be no load at all, I would have thought it wouldn't or shouldn't have been any different then normal driving where I can do 70-80 in OD. now I wasn't thinking about the wind resistance but I don't see a reason that a low profile flatboat with no flat areas that are blocking the wind, should produce all that much drag but I guess it does

 

Does anyone ever consider the aerodynamic drag of a trailer? Based on what I know from cycling, it could easily be the one factor that limits the top speed to 65 mph.

Once you hook up the trailer, you are putting a large mass out behind the slipstream of the vehicle towing it. And the faster you go, aerodynamic drag becomes a much bigger factor.

Sure, Toyota says my truck can pull 3500 pounds. However, it does not take into consideration that actual size mass of what I'm towing.

 

not saying I disagree with you, I drive a motorcycle so I know how bad wind resistance can be, it was just a shock how weak the 4 banger is, that is all.

I think most people wrongly assume whats in front (the truck) blocks the wind and makes a big hole in the air that the trailer rides in but the truck actually funnels and redirects the air force down and directly into it more then if it were going down the road on its own without a truck in front of it.