Throttle Input and Lack of Power

Hello!

For years, I've noticed that my 2000 Tacoma (2.4, auto) has both been quite slow (12-13 second 0-60) and upshifts early under full throttle (~4500 1-2, <5000 2-3). I've connected an OBDII reader and noticed that it won't read more than ~80% throttle input, no matter how hard I press the accelerater petal or twist what the cable is attached to under the hood. It will rev up to 5000-5500 if I manually shift it into 1st or 2nd, so I know it's not a rev limiter issue -- The 2RZ-FE should have a max of 5500 rpm and tachs on other 2.4 models show that as the redline.

I've looked at service records and within the past 50k miles, the spark plugs and oxygen sensors have been replaced and the mass airflow sensor has been cleaned. I've had the truck for ~30k miles and 5 years, and I've noticed this the whole time. Would it be a fuel pump/filter issue, or is there something else that could be going on? Otherwise, the engine and transmission work excellently -- Plus, it's only at about 154k miles.

Thanks!

 

CE codes?

 

The only codes I've gotten since getting the truck were for an oxygen sensor, which I then replaced.

 

If you use your hand to fully open the throttle plate instead of the pedal, what's your max reading? Throttle plates never open 100% but they should report they do, to my knowledge

 

Have someone press the throttle in the cab to the floor and see if it opens the throttle fully. If that is ok there is a Throttle Valve (TV) cable that goes from the throttle body to the transmission. This cable “tells” the transmission how much throttle you are giving the motor. At the throttle body where the TV cable goes through the bracket there should be a black rubber cover where the multi-strand cable exits the housing. Pull this boot back and you will see a crimped ring on the multi strand cable. The outside of the crimped ring should be even with the end of the housing, if not, loosen the locknuts and you can extend or shorten the housing to get the adjustment. Dont get fancy with this adjustment… this is what sets/modifies the hydraulic pressures inside the transmission and sets the shift points.

 

If I remember correctly, it's something like 78% max reading. I'm not sure if it would be higher manually opening the throttle itself, but the bit under the hood that the cable connects to (it looks like there's another cable going elsewhere) only reads up to the ~78%

 

I'll take a look at this when I have a chance!

 

A new TPS might not hurt, ~$25 last I checked. But if your cable is too stretched to open it all the way that's a different issue entirely, which is why you should use your hand to see.

 

My understanding is different. Or at least that the reading you see over ODBII is not calibrated. A TPS might send (from 0-100) a range of closed (5) through open (80). The ECU knows 5 = 0 and 80 = 100, but the ODBII reader doesn't know that, and reports 80 as 80% and not 100%. I could be totally wrong though.

 

That's totally possible! I believe that the OBDII reader reads down to 0, but I'll need to check to know for sure.

 

Scan gauge II shows TPS reading as 10-70 readings assuming TPS is set properly. Not as %, at least on mine. That’s how I set the TPS up instead of doing the volt meter version. Moved TPS at idle till it read 10 and sent it.

 

You're right, I just checked and mine goes from 10-75%