Hesitation and mushy gas pedal help

[Golfinz]

I've noticed this past weekend that the T4R is acting funny while on the highway. I've included a video of the rpm gauge to illustrate what I'm seeing/whats happening - it happens at the :16 and :21 second mark.


https://www.youtube.com/watch?v=7dYRTCdqh0k

The typical scenario is this: I'm cruising on the highway, holding the car at a constant speed (ie: not accelerating or not decelerating) and the rpms will start to dip and bounce like it does in the video at the 16 and 21 second mark. When this happens, the car will slow down as the rpms dip and if I try to accelerate, the gas pedal feels mushy/like I'm trying to push the pedal through peanut butter (ie: I can press it down but it is very hard to do so). While this is happening, the car does not react to the additional pressing of the accelerator. After a few seconds, it will 'kick in' and the rpms will jump up and the car will start accelerating again as I gain control over the gas pedal. This typically happens right at the 1800-2200 rpm mark and does not happen when I am accelerating or below/above this rpm range.

The check engine light is not on nor is it so bad that it truly interferes with the trucks ability to drive; hell, I drove 1200 miles this weekend alone without missing a beat. I would like to try to figure this out before anything serious happens. Its a 2002 limited, 4wd with 171k miles on it

 

[Golfinz]

Bump! I was thinking that since the pedal changes "feel" that it wouldn't be a clogged injector or bad plug. Those would just cause the car to miss. Could this be a tps issue? I have a 2002, which based on what I've read on the forums, I can't just replaced the tps but would have to replace the entire tb

 

[1da4]

my girlfriend had a similar problem with her rav4, turned out to be a bad catalytic converter.

 

[Golfinz]

Would be surprised if it was a cat. Someone on yotatech recommended that I clean my tb and maf - probably going to start there

 

[Neil_R]

Would be surprised if it was a cat. Someone on yotatech recommended that I clean my tb and maf - probably going to start there

Pedal feel really shouldnt change at all on these trucks. I'd suggest removing the TB and giving it and the TPS/IACV a good cleaning. That should rule that out.

Is it throwing any codes?

 

[TheeMikeB]

Sounds like fuel delivery issue. Def check the basics especially the MAF, TB, and air filter. I recently had a 'dead spot' in mine in 3rd around 2500RPM and wasn't throwing codes but turned out to be dirty MAF. Use the proper MAF cleaner and give it a shot.

Not sure about the pedal feel... maybe it just feels dead because it's not accelerating?

 

[Golfinz]

Pedal feel really shouldnt change at all on these trucks. I'd suggest removing the TB and giving it and the TPS/IACV a good cleaning. That should rule that out.

Is it throwing any codes?

Ill try removing the TB and cleaning it. There isn't a check engine light on, but unsure if its throwing a code. Now that I think about it, my z06 will throw codes and not kick on a SES light. I'll run by autozone and have them check for any codes.

Sounds like fuel delivery issue. Def check the basics especially the MAF, TB, and air filter. I recently had a 'dead spot' in mine in 3rd around 2500RPM and wasn't throwing codes but turned out to be dirty MAF. Use the proper MAF cleaner and give it a shot.

Not sure about the pedal feel... maybe it just feels dead because it's not accelerating?

Fuel delivery is what I originally thought but since it doesn't happen more often/at varying rpm's, I initially ruled it out in my head. I don't have any injectors at the house, but I could throw some injector cleaner in my next tank of gas

As for the pedal feel, that's the "weirdest" part about this whole thing. When the rpm's dip/bounce like in the video, if I press on the pedal, it feels like there is a mattress behind the pedal (ie: it moves but is stiff). It's only after a few seconds that the car reacts and the easiest way to make the car react is to slow down and take my foot off the pedal

Thanks for the replies! Keep them coming!

 

[TheeMikeB]

Ill try removing the TB and cleaning it. There isn't a check engine light on, but unsure if its throwing a code. Now that I think about it, my z06 will throw codes and not kick on a SES light. I'll run by autozone and have them check for any codes.



Fuel delivery is what I originally thought but since it doesn't happen more often/at varying rpm's, I initially ruled it out in my head. I don't have any injectors at the house, but I could throw some injector cleaner in my next tank of gas

As for the pedal feel, that's the "weirdest" part about this whole thing. When the rpm's dip/bounce like in the video, if I press on the pedal, it feels like there is a mattress behind the pedal (ie: it moves but is stiff). It's only after a few seconds that the car reacts and the easiest way to make the car react is to slow down and take my foot off the pedal

Thanks for the replies! Keep them coming!

Make sure you just don't 'shotgun' approach it, start with one thing and do one at a time. The Air Filter and MAF is simplest.quickest, then TB cleaning and injectors. Although not sure if a bottle of injector cleaner would do it, if it's that bad and it is the injectors you would probably need to have them serviced professionally. http://www.cruzinperformance.com/fuelinj.html

 

[Golfinz]

Good idea. I went by Autozone to have the codes pulled and a P0420 came up. Can this code come up without a SES, because I don't have an SES light on.

I did replace my rear 02 sensor in January because of this code but at that time, I did have the SES light on. When I replaced the sensor, the light went away and it hasn't come back on since.

 

[Golfinz]

I also cleaned my maf and TB last night. Will report back if it helped

 

[infamousRNR]

Maf & tps

3x on that MAF...

No codes??? No CEL??

Tps replacement. Someone was selling them on here for cheap..
And potentially cleaning your throttle body..


Make sure you clean both sides of the amber bulb and inside the MAF...

 

[Golfinz]

3x on that MAF...

No codes??? No CEL??

Tps replacement. Someone was selling them on here for cheap..
And potentially cleaning your throttle body..


Make sure you clean both sides of the amber bulb and inside the MAF...

I cleaned my maf and throttle body last night. Will report back if that helped - my commute to/from work doesn't require me to get on the hwy so I will drive around late tonight.

Since my t4r is an 02, I didn't think I could just replace the tps. I thought the 01 and 02's were integrated.

I do not have a CEL but do have a P0420 code per the reader from autozone

 

[jgue467]

P0420 (Catalyst System Efficiency Below
Threshold (Bank 1)) per our beloved FSM says to look/check on:
1. Gas leakage on exhaust system

2. A/F sensor (bank 1 sensor 1)

3. Heated oxygen sensor (bank 1 sensor 2) and/or

4. Three-way catalytic converter

The ECM is comparing the 2 02 sensors (one before and one after the cat) and is not finding enough of a difference which is caused by one or more of the 4 above. This usually doesn't cause driveability issues so perhaps there is more to your story. So study the FSM and its test procedures, its what a toyo tech would do. Check/make changes in that order as the price increase with the number. Luck.