Gas pedal to the floor, doesn’t want to downshift

[spartacus]

Both of you have my same problem. Pressing the pedal to floor doesn't change RPMs or the noise the engine should be making when you are trying to accelerate. .

There might be a dead spot on you tps if you are not getting any response from the throttle. When you are manully down shifting into 2nd, the transmission is already in 2nd and that's why you don't get a rpm spike when you move the automatic shifter from D to 2.
In my experience the TC locks, and the rpms will drop. Once you push the pedal to the floor the TC unlocks and the rpms go up. With the power loss at that altitude specially Floyd hill, Eisenhower pass there is just not enough hp in the motor. My truck down shifts to 2nd the rpms go up and doing about 60 mph even on 7% incline rpms at about 3500 to 4000rpms. That's just normal for 20 year old motors.

 

[jross20]

There might be a dead spot on you tps if you are not getting any response from the throttle. When you are manully down shifting into 2nd, the transmission is already in 2nd and that's why you don't get a rpm spike when you move the automatic shifter from D to 2.
In my experience the TC locks, and the rpms will drop. Once you push the pedal to the floor the TC unlocks and the rpms go up. With the power loss at that altitude specially Floyd hill, Eisenhower pass there is just not enough hp in the motor. My truck down shifts to 2nd the rpms go up and doing about 60 mph even on 7% incline rpms at about 3500 to 4000rpms. That's just normal for 20 year old motors.

Well but see everybody keeps saying that that's normal, it's only 180 horsepower, etc... But I'm starting to wonder if some of that is just maybe people getting used to the lower amount of power and just thinking that it's normal?

I mean I've literally been passed by another third gym pulling a big trailer uphill in the mountains, there was literally no way I could keep up with him. I mean I actually try because I was thinking well hey if he can do it I can too!

Nope. Pedal to the floor RPM's up to 4000+... Not even close, I just watched to see drove off into the distance uphill.

I mean maybe he was supercharged, but again I just have this theory that we're all actually missing a lot of horses then just don't realize. I test drove a lot of these when I was trying to find one to buy years ago and I recall noting that they all seem to have varying amounts of power. Some of them were a lot quicker than others.

I've actually been trying to find a place that could Dyno it so we could literally see the exact number of horses she still has. I feel like that would be the ultimate deciding factor.

 

[Romeo1]

Another factor here, one for sure worth discussing is do you have E load rated truck tires on? If you do what are they inflated to?

Because I have to tell you guys, I’m pretty sure my 4runner has more miles than almost all of yours, and mine still averages 19mpg with a cruise set 70 mile an hour on the eight hour haul to Moab. It will do 80, but it’s not happy at 80, it’s super happy at 70 mph.

BUT, my tires are never less than 38 psi for a road haul. At less than 35, say 28-30, the 4runner literally can’t even get to interstate speed. In fact at the nice cushy 28 to 30 for the around town stuff, it can’t hardly even crack 60 to 65 mph without straining to death.

Are your tires inflated to the proper psi for road travel? Not what’s “comfortable” but the actual needed psi? Because I’m here to tell you, with load range E tires you will absolutely slaughter the drivable speed of these machines. Go test it for yourself, find a country Road and run a low pressure and a high pressure run. Seeing is believing on that one. It feels like a difference of 50 to 100 hp.

I have a fresh set of loads C general grabbers just to go further test that one out. My theory is is that these machines absolutely don’t need an E load tire. Took a little while but I found a C rated tire with a 3ply sidewall that seems to be durable enough to survive abuse on the rocks.

Don’t discount tires on this one. My engine pulls 145 psi compression at almost 4000 feet elevation. Under inflated tires will absolutely bring her to her knees on the highway.

 

[Bad Luck]

The P0420 will kill your gas mileage and power, pretty much every Check Engine Light will. It's seeing air in the exhaust and trying to tune it out. Have a shop weld it up or replace the offending section and power should start to come back.

P0420 is for catalytic converter low efficiency. It uses the 2nd (downstream) oxygen sensor and does nothing to fuel trims at all. The first oxygen sensor (or air/fuel sensor is what the ECM uses to make changes to fuel trims.

 

[Romeo1]

There might be a dead spot on you tps if you are not getting any response from the throttle. When you are manully down shifting into 2nd, the transmission is already in 2nd and that's why you don't get a rpm spike when you move the automatic shifter from D to 2.
In my experience the TC locks, and the rpms will drop. Once you push the pedal to the floor the TC unlocks and the rpms go up. With the power loss at that altitude specially Floyd hill, Eisenhower pass there is just not enough hp in the motor. My truck down shifts to 2nd the rpms go up and doing about 60 mph even on 7% incline rpms at about 3500 to 4000rpms. That's just normal for 20 year old motors.

TPS is another possibility. Dead zones do happen. Easy to diagnose also. Plug in your flavor of OBD2 and verify.

 

[jross20]

TPS is another possibility. Dead zones do happen. Easy to diagnose also. Plug in your flavor of OBD2 and verify.

Will this work with electrics on but engine off? That would be a bit safer.. haha

 

[gamefreakgc]

P0420 is for catalytic converter low efficiency. It uses the 2nd (downstream) oxygen sensor and does nothing to fuel trims at all. The first oxygen sensor (or air/fuel sensor is what the ECM uses to make changes to fuel trims.

I confirmed with my 98 that the rear O2 sensor does adjust LTFT. I have an aftermarket wideband AFR sensor and the drive after I replaced my original rear O2 sensor the wideband was reading a full 1.0 AFR leaner than before I had changed it 30 minutes earlier. That meant my rear O2 sensor was skewing the trims rich. I too was under the impression it was just a cat sniffer but it does more than that.

 

[gamefreakgc]

Will this work with electrics on but engine off? That would be a but safer.. haha

Yes, key on but engine off. Slowly press the throttle and the percentage should move in a linear manner. Some OBD readers will say something stupid like you're at 140% throttle but just ignore the actual value and watch to see if it freezes at a certain point. Could also try to view in voltage and not percentage.

Also the throttle cable must be near tight when fully closed. A photo of where it sits right now would be super helpful in telling if it's tight enough. Some cables stretch beyond the point of adjustment - mine did that so I couldn't get it fully tight anymore.

 

[Bad Luck]

I confirmed with my 98 that the rear O2 sensor does adjust LTFT. I have an aftermarket wideband AFR sensor and the drive after I replaced my original rear O2 sensor the wideband was reading a full 1.0 AFR leaner than before I had changed it 30 minutes earlier. That meant my rear O2 sensor was skewing the trims rich. I too was under the impression it was just a cat sniffer but it does more than that.

I'll stick with what the FSM says.

 

[Romeo1]

Will this work with electrics on but engine off? That would be a bit safer.. haha

Yes. Any diagnostic tool or obs2 gauge worth its salt will provide voltage and percentage of the throttle position sensor in key on engine running or key on engine off states.

 

[jross20]

Yes. Any diagnostic tool or obs2 gauge worth its salt will provide voltage and percentage of the throttle position sensor in key on engine running or key on engine off states.

Alright that I can do. Currently my damn neck issues have flaired up so I'm limited with movent right now...