Maintenance continued; low power when warm

[jross20]

Alright so I'm updating this original post with the solutions that have nearly fixed my issues.

The original issues were that my girl just had this bad lack of power, it seemed to be related to cold/warm conditions. More power when cold. Etc. I also had a cruise control issue, it jerked a lot and I was not aware that this was a problem until I changed the throttle position sensor.

Fixes so far:
-Replaced throttle position sensor (OEM)
-Replaced accelerator cable assembly (OEM)

So far my truck is running MUCH better now and has power again. I can pass and also merge into traffic more safely now. Fuel economy has jumped from 18.5 average to about 19.5 but more fill up are required to confirm. Never the less, she drives much better now

I'm still going to replace the 02 sensors to see if there is any additional power I can bring back and also see if the cat is hindering the exhaust just to be on the safe side.

Hope this helps anyone who thinks they are missing some HP.

2000, SR5, V6, 138K miles

 

[LittleCaesar]

How do your short and long fuel trims look once warmed up? Possibly a vacuum leak.

 

[plcfcng]

something to consider is a clogged CAT I had that problem 6 months ago. You can test by using a vac gauge or take the front O-2 sensor out and drive it and see if this improves performance.:noidea:

 

[gamefreakgc]

It's not the knock sensor, it does not affect power or timing until over 3000 RPM's. Crank position is an all or nothing sensor, either it work great or doesn't and your 4Runner won't even start. TPS is a possibility though.

The most important sensor in regards to power and fuel control is the MAF. I'd start there if you suspect any issues. A good cleaning of the delicate wires is a great place to start.

A comment on power though, you will make more power when the engine is cold than warm. Warm engines heat up the intake charge and cause it to lose power. Even a 10 degree difference is enough to start affecting the power output, that's why performance builds chase after "cold air intakes". Really does make a difference.

 

[Thebeastlives]

Not really understanding the issue because a 3rd gen forerunner never had power even 25 years ago when new it was a turd compared to my other vehicles. My Jeep 2001 Cherokee was much faster than my 96 3rd gen 4 runner. Damn my 92 Cherokee limited had much more power than this thing. It is slow but reliable n built to last..lol

 

[jross20]

How do your short and long fuel trims look once warmed up? Possibly a vacuum leak.

I'll have to try to record it and see. Another issue I have is that in torque pro, the values just randomly jump up and down sometimes. Like, graphs or scales will max out or go negative for a moment... I still don't know of this is normal.

something to consider is a clogged CAT I had that problem 6 months ago. You can test by using a vac gauge or take the front O-2 sensor out and drive it and see if this improves performance.:noidea:

I started thinking about that, but would that fluctuate while driving ever see all? I guess it wouldn't hurt to try it. Do you just unplug the sensor and set it in the garage or something? Will the exhaust gases hurt anything or is is in a safe area?

It's not the knock sensor, it does not affect power or timing until over 3000 RPM's. Crank position is an all or nothing sensor, either it work great or doesn't and your 4Runner won't even start. TPS is a possibility though.

The most important sensor in regards to power and fuel control is the MAF. I'd start there if you suspect any issues. A good cleaning of the delicate wires is a great place to start.

A comment on power though, you will make more power when the engine is cold than warm. Warm engines heat up the intake charge and cause it to lose power. Even a 10 degree difference is enough to start affecting the power output, that's why performance builds chase after "cold air intakes". Really does make a difference.

I did replace the MAF which... Maybe base a difference? Not sure really. Haha. I see what you say about heat on the intake... But this feels like a considerable amount of ponies, at least to me.

I went ahead and ordered the TPS, had some Amazon points and figured what the hell. We will see if it helps.

What about the 02 sensors?

Not really understanding the issue because a 3rd gen forerunner never had power even 25 years ago when new it was a turd compared to my other vehicles. My Jeep 2001 Cherokee was much faster than my 96 3rd gen 4 runner. Damn my 92 Cherokee limited had much more power than this thing. It is slow but reliable n built to last..lol

When things are working as they should the v6 feels great to me. 0-60 isn't great, but the 0-15 mph, 0-30 mph are fast to me. It isn't always about 0-60, haha.

 

[Thebeastlives]

I'll have to try to record it and see. Another issue I have is that in torque pro, the values just randomly jump up and down sometimes. Like, graphs or scales will max out or go negative for a moment... I still don't know of this is normal.



I started thinking about that, but would that fluctuate while driving ever see all? I guess it wouldn't hurt to try it. Do you just unplug the sensor and set it in the garage or something? Will the exhaust gases hurt anything or is is in a safe area?



I did replace the MAF which... Maybe base a difference? Not sure really. Haha. I see what you say about heat on the intake... But this feels like a considerable amount of ponies, at least to me.

I went ahead and ordered the TPS, had some Amazon points and figured what the hell. We will see if it helps.

What about the 02 sensors?



When things are working as they should the v6 feels great to me. 0-60 isn't great, but the 0-15 mph, 0-30 mph are fast to me. It isn't always about 0-60, haha.

What? 0 to 15 , 0 to 30, damn 0 to 5 is damn slow. It is a under 200 hp 25 year old motor and transmission. This thing could not beat a modern non turbo utv. Just deal with that it is a old suv with super reliability but terrible performance for our 2020 world.

 

[LittleCaesar]

Then if TP is throwing you garbage for data you need to find another live data scanner. If you have a big enough vacuum leak the money light would be tripped, but this doesn’t sound like the case, yet you can’t rule such out.

 

[plcfcng]

just unbolt the sensor there are just 2 nuts or bolts. Just wire it off to the side and drive it a short distance see if the power improves. A muffler shop can do a test on a cat for about 25 dollars they drill a small hole and do a gas analysis. A Vac gauge plugged in to a Vacuum port port and just read gauge if vac is low most likely a clogged cat. This problem is for me never threw a code but I chased for a couple of weeks. I did not think I had a cat problem because it would throttle cleanly when in park but was a slug going down the road.:wacko:

 

[jross20]

What? 0 to 15 , 0 to 30, damn 0 to 5 is damn slow. It is a under 200 hp 25 year old motor and transmission. This thing could not beat a modern non turbo utv. Just deal with that it is a old suv with super reliability but terrible performance for our 2020 world.

I think you're being a bit overdramatic my friend. I don't think the performance is terrible at all. Sure it isn't super fast, but they are nimble in my opinion. That's why I said it isn't always about 0-60.

Plus this has to do with power, bogging, not purely acceleration.

Then if TP is throwing you garbage for data you need to find another live data scanner. If you have a big enough vacuum leak the money light would be tripped, but this doesn’t sound like the case, yet you can’t rule such out.

When you say TP are you referring to the throttle position sensor? Or do you mean my obd2 scanner? that does give me the idea to try the scanner in a different vehicle and see if it's weird.

just unbolt the sensor there are just 2 nuts or bolts. Just wire it off to the side and drive it a short distance see if the power improves. A muffler shop can do a test on a cat for about 25 dollars they drill a small hole and do a gas analysis. A Vac gauge plugged in to a Vacuum port port and just read gauge if vac is low most likely a clogged cat. This problem is for me never threw a code but I chased for a couple of weeks. I did not think I had a cat problem because it would throttle cleanly when in park but was a slug going down the road.:wacko:

Gotcha, that doesn't sound too bad. Gosh I didn't think it would be okay to drill a hole in the cat. How do they plug it up after? Haha.

I think I have an old vac gauge, the little hand held one with the gauge reading right? What's a good hookup point?

Oh whoa, I just had a thought. Would a vacuum leak also cause issues when shifting into 4wd? Mine has always been really slow and delayed, I think that's vacuum operated isn't it?

 

[LittleCaesar]

No, torque pro. I am all for opening up the parts cannon (OEM for this 4Runner) if one has deep pockets. But try and get some good data first to try and discern what the problem could be if the money light isn’t lit.

 

[plcfcng]

As far as a muffler shop doing a test i'm sure they just weld up the hole. For the vac gauge I don't recall what i used a mainifold vac port is the best but I think a ported opening would be ok too. Mainline you could use the pressure regulator, ported egr is easy to get to. Put the gauge in start it open the throttle if the gauge says low vac it is most likelly clogged CAT. If gauge reads normal than this rules out a restricted exhaust and you need to look some where else.

 

[Dieselchessy]

Would a clogged cat exhibit good power when cold but poor power when warm?
Hard to wrap my mind around that.

Throttle position reading should be smooth and linear and track with pedal position. If it’s jumpy replace it.

You said you replaced the MAF. Did you say what with?

How is your fuel mileage?
When was the last time you replaced the front O2 sensor, and with what?

 

[Thebeastlives]

I think you're being a bit overdramatic my friend. I don't think the performance is terrible at all. Sure it isn't super fast, but they are nimble in my opinion. That's why I said it isn't always about 0-60.

/QUOTE]

Overdramatic? Lol Look I've owned my 96 3rd gen 4 runner for about 15 years now. It was my oldest son's first car. It was slow for him then. It is the slowest vehicle I've owned in 30 years. It has never beat a car from light to light even my old Yamaha Rhino (760 Motor 1) was faster. My 4th gen and 5th gen 4 runners are not very quick either but the power in those vehicles far exceed the 3rd gen. Try climbing a mtn pass and keep up with anything? At 5000 lbs + and 183 hp and 217 lbs of torque it was NEVER nimble and I've never met anyone who described a 3rd gen non boost vehicle as nimble, quick, etc. It is slow and after 15 years of ownership it is the oldest, slowest, and longest vehicle I've ever owned and truly 1 of the most reliable. The only time it was slower than it is now is when the cat went bad and spark plugs needed replacing. I know speed and performance can be very subjective to many but when I tune a performance vehicle of mine I take out the "feel" of speed out the equation and always record my times. It is super simple to do and that way you know if you are going in the right direction or you have issues. Toyota 0-60 Times | Toyota | SuperCars.net
The 3rd gen 4 runner is turd when you look at the stock numbers of 9.5 0 to 60 and over 15 secs to 1/4 mile. The 4th gen and 5th gen have more acceptable numbers for a non sport SUV but they have more modern transmission and motors compared to the 3rd. It is a Turd of a SUV but try finding a more reliable SUV.

 

[Dieselchessy]

All my 22r trucks, 2.5 liter wrangler, 3 liter 4-runner, ect... are slower and much more noticeable when you add a passenger or two.
The 3.4 liter 4runner has never seemed like a dog to me. Not a race car, but plenty of power to get around.
Never had issues going the speed limit anywhere I’ve been.

 

[phattyduck]

I did replace the MAF which... Maybe base a difference? Not sure really. Haha. I see what you say about heat on the intake... But this feels like a considerable amount of ponies, at least to me.

I went ahead and ordered the TPS, had some Amazon points and figured what the hell. We will see if it helps.

What about the 02 sensors?

Whoa, whoa, whoa... car parts off Amazon? That might be your problem right there. Amazon and eBay are full of crap parts, even ones sold as OEM are often knock-offs.

A bad MAF sensor would cause major issues.

-Charlie

 

[jross20]

Would a clogged cat exhibit good power when cold but poor power when warm?
Hard to wrap my mind around that.

Throttle position reading should be smooth and linear and track with pedal position. If it’s jumpy replace it.

You said you replaced the MAF. Did you say what with?

How is your fuel mileage?
When was the last time you replaced the front O2 sensor, and with what?

See that's what I don't get. I'm hoping to test it this weekend and find rule the cat out.

I went ahead and ordered a TPS as I had some Amazon points, was one of those "ah what the hell why not" moments.

I replaced the MAF with an oem from Mcgeorge totoya.

See mileage...is odd. If I drive "normally/conservatively" I average 16-17. If I drive spirited, accelerate pretty quickly all the time, I average high 18-19s. My weekly commute is identical and rarely deviations. I never use drive thru's or do any other idling unless it is at a stop light. These averages are from 6 months of doing the math at the pump.

The wide variance and the increased in economy from driving faster just make no sense to me. That is one of the reasons why I thought the engine was bogging, like maybe when I give her more gas she doesn't bog and thus works more efficiently.

I've noticed that on some hills on my commute that sometimes she struggles and has to drop to what feels like 2nd and the rpm's get close to 4,000 or so, but other times it just feels like a gentle drop to 3rd and she powers right up without the slightest hint of issue. I recall the power from test driving other 3rd gens as being exceptional when you just convinced the transmission to unlock or drop to 3rd, never did I need to revv past like 3500 to speed up or go up a hill. I mean unless I was going nuts haha.

I specifically remember being impressed and really enjoying driving them during the test drives.
And I'm pretty sure that not a single one of them were supercharged or something lol.

Anyway. I'm going to run some seafoam as well to see if that helps. Also going to get a vacuum gauge for testing, I had no idea how useful they could be and I feel like I should just have one regardless.

 

[jross20]

Whoa, whoa, whoa... car parts off Amazon? That might be your problem right there. Amazon and eBay are full of crap parts, even ones sold as OEM are often knock-offs.

A bad MAF sensor would cause major issues.

-Charlie

Oh don't worry, after learning a while back I don't just blindly order. I pretty much read every comment and ask questions to make sure it is legit. I check the seller, all that. But generally I order from mcgeorge Toyota.

The new MAF I have is from mcgeorge.

 

[spartacus]

you can look at vendor information on the seller. Lots of dealers sell items through amazon. check the return address on the package if suspicious.

 

[Dieselchessy]

Maybe you have tranny issues. Maybe it runs out good with cool thick fluid, but then slips when heated up.
Maybe driving spirited helps it lock up the TC and Driving miss Daisy has the TC slipping?

I’m stretching here.

What’s the service history on the tranny?