1-2 Minutes truck loses some power 3rd Gen :hunter:

[DirtyDoctor]

2002 3rd GEN 255K
I drive the truck from 1-2 minutes and it loses some power (in all gears). There is also a slight hesitation at higher speeds (RPMs). It almost feels like a fuel filter but not as extreme of a bog down. This issue has gone on for over a year. I have read just about every forum post on this issue and tried most everything that was a “fix”. The truck is very drivable there is just no get up and go like in the first 1-2 minutes of driving.
When I am higher speeds (40-70mph) the engine’s RPMs goes up but truck does not seem to accelerate much. I ruled out a transmission bc it goes fast for the first 1-2 minutes. I could let the truck sit for 10min(even when driven up to temperature) then get back in and same 1-2 minutes of great pedal response then sluggish.

:laser:Here is a list of what I have done to date (in order):
Changed Fuel Filter
Cleaned MAF sensor (Might need to change it I am not sure). Cleaned with MAF cleaner
Cleaned throttle body but did not take it apart.
Coils, plugs, wires all denso or Toyota OEM (plugs are single pronged)
Front O2 sensor replaced (Denso)
Front Catalytic converter replaced (Universal)
Rear Catalytic converter removed (deleted)
TPS throttle position sensor
Changed Coolant temp Sensor
Took it to a local mechanic and he could not find the issue. He said he did a fuel pressure check when I asked but I did not ask if it was done after driving for 5 minutes.

ANY HELP MUCH APPRECIATED

 

[Bad Luck]

Sounds like a torque converter issue to me

 

[DirtyDoctor]

Sounds like a torque converter issue to me

Is there anyway to check if a TQ Conv is bad?

 

[19963.4lsr5]

Is there anyway to check if a TQ Conv is bad?

You said at higher speeds the rpm’s will go up but you don’t go any faster…..

It possible TC is not locking up.


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[_Ace_]

Sounds like a possible fuel delivery issue like a filter, pump , regulator or maybe a clogged pickup screen in the tank.

You might try a full can of Seafoam into a tank of fresh, alcohol free premium fuel.

 

[DirtyDoctor]

You said at higher speeds the rpm’s will go up but you don’t go any faster…..

It possible TC is not locking up.


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It does not accelerate much, but it does accelerate. As in on flat land it will drop gear and then it will go from 60 to 70mph in a slow amount of time. But if I am on a grade(hill) it will drop 2 gears and the rpms go up to 4 or 5 and accelerates extremely slow. I do not allow the car to drop down into the 3rd gear because the rpms are so high. I can maintain speed most of the time on small to medium grades just by dropping to 4th gear (it is an automatic btw).
Thanks for the time and info (everyone)

 

[DirtyDoctor]

Sounds like a possible fuel delivery issue like a filter, pump , regulator or maybe a clogged pickup screen in the tank.

You might try a full can of Seafoam into a tank of fresh, alcohol free premium fuel.

This was my thought and still a possibility. I am going to try this, cannot hurt! Thank you

 

[Bad Luck]

Is there anyway to check if a TQ Conv is bad?

Not what you probably want to hear, but you should take it to a reputable transmission shop if you want the torque converter diagnosed. So maybe eliminate some other things that other people are suggesting before going that route.

 

[jross20]

Sounds like what I've had for a long time. I JUST found out that I have an exhaust leak. I mistakenly took the noise and smell as a product of "not having an oem" cat. A good mechanic I started using about 6 months ago for things I don't have the time/tools/space for, did a couple of smoke tests and we found that the new cat was defective. It doesn't mount flush, though the gap is tiny.

At first my cat was clogged, but then with the new one I've had an exhaust leak this whole time. I feel like an idiot but love and learn I guess.

You replaced your cat's, did you experience any change in sound? If so a smoke test might not hurt. My understanding is that a leak can confuse the computer and reduce power. I "think".

 

[DirtyDoctor]

I would imagine it is possible... I am sure I have a leak down stream past both O2 sensors. I changed the MAF sensor today (Denso) there was a change in power but same issue creeped up.

 

[DirtyDoctor]

This was my thought and still a possibility. I am going to try this, cannot hurt! Thank you

I did do this with 2 tanks of gas...no love

 

[19963.4lsr5]

It seems that when it goes closed loop you loose power.


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[skippyenthalpy]

proabably tq

 

[DirtyDoctor]

It seems that when it goes closed loop you loose power.


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\
What does that mean? Up to temp?

 

[Devbot]

Are you talking about the first few minutes after a dead cold start before everything is up to temp? That's very normal if so. I have maybe half the power until my needle breaks the line, and maybe 75% until it hits the middle - then from there it's golden. If so, you also probably noticed you hang revs and are hesitant to change gears during this time as well. All of which are to bring the trans fluid up to temp quicker; how well it works I'm not sure because it's clearly based off engine temp rather than trans temp, but that's the idea behind it.

 

[19963.4lsr5]

\
What does that mean? Up to temp?

At cold start the engine uses adaptive and fixed parameters to start the engine and then keep it running. (Adaptive being things like IAC position for given engine and air inlet temp for a desired rpm) (fixed being things like fuel and spark maps).

As soon as the ECU sees a valid input from the front O2 sensor (voltage creeps up to around .85vdc) it goes closed loop and starts the enrichment warmup process where you will see the O2 voltage cycling high low. Starting around 10:1af and slowly going up to 14.7:1.

Until the engine hits around 130-140 it’s running 13:1 or less and that makes more power.


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