bloomwcjkl

I have an 01 LS 430 with ~130k.

No codes being thrown. I changed the Air Filter, Mass Airflow Sensor and reset the ECU.

Symptom: When driving around, occasionally the throttle/pedal will just disappear. It seems like when slowing down and turning is the most common. Or I have the cruise set, slow down for an intersection it might happen.

It didn't happen for a few hundred miles after resetting the ECU, but it is back to happening again. The car has not died, but it seems to be happening more frequently again.

I've read some threads. Does this seem like Throttle or Pedal Position or both? I also read a thread that said I could have slack in the throttle cable.

Is this a "bring it to the shop, don't mess with it" situation or a DIY scenario? Try the lower cost Throttle Position Sensor first?

Thanks in advance for a direction you would take.

Bocatrip

I Have your symptoms for many years. Took to Lexus. Unable to find anything. No codes. Drive by wire issue. All parts are expensive and there are a number of them. Can't find the culprit until total failure. Very sporadic for me. Can go a year before feeling the slowing down or can happen every other day for a week. Have learned to live with it. I too have 01 LS430 with 130,864 miles.

2013FSport

iTrader: (2)

Try this; ignition on only. Engine off.
Press accelerator down smoothly and evenly. Let up in the same fashion. Repeat 4x. Turn ignition off.

Go drive.
TBW Yodas, Chev, and Mazda all get out of sync. Sluggish and then you notice transmission shift points are erratic. This corrects it for 3 mo or so.

Doing this after ECU reset made the Mazda feel it gained 20hp...

Last bit, grab a Bluetooth OBDII elm reader and Android Torque Pro and read the TBW data. Log when it's working well and when it's messed up and compare them. The pair have like 4 different channels of data used to verify TB position is related to peddle position.
Good luck...

911LE

My '01 with 128k miles does the same thing. If I just putt around there is no issue but as soon as I get on the throttle to pass someone or when I pull out in front of someone there is nothing. It's like I haven't moved the pedal at all and sometimes if takes several seconds to respond. I guessing that the problem is with the pedal sensor itself because there are no codes set. If it was a TPS or a throttle plate motor issue there would be a code. I just bought Techstream so I can diagnose this problem without just throwing parts at it. As soon as I have some time to investigate I will post the results. Still working crazy hours but we should be slowing down soon.

bloomwcjkl

Thanks. This is what I have been doing. Just driving. I know I can deal with the occasional drop in pedal.

I'm a bit worried about someone else driving and experiencing the fade away and not dealing with it.

I will try the pedal adjust steps listed above. I don't mind spending a few dollars if something will get fixed. I could start with a $59 throttle position sensor and work up in cost. But only if I had some hope of fixing the problem.

I worry that something will fail and the car will die in a traffic scenario. Loss of pedal becomes something worse I guess.

Thanks again for the reply.

bloomwcjkl

This seems like a different issue. Maybe fuel filter or fuel pump? There are some threads about this issue.

When the pedal drops away, if I step on it, it comes back. If I am starting from a stop, I have great power and can stomp on it without hesitation. It is like it forgets where the gas pedal is positioned.

911LE

After yesterday I can now say that the problem is with the accelerator pedal sensor. My car has been getting worse with the symptoms listed above. If I wasn't slowly accelerating there was nothing there. Yesterday as I was leaving work the problem was the worst it has ever been and every time I tried to accelerate it would keep cutting out . This happened after working a 14.5 hour day in the Phoenix heat, on my way home. Due to frustration/desperation I tried the only remedy a rational person would do. I kicked the side of the accelerator pedal 5 times, hard. Since then it has performed flawlessly. It is 100% better and hasn't had a hiccup.

I have read about similar issues on other vehicles and there is some rationale as to why this worked. The pedal position sensor (PPS) is a mechanical rheostat and can succomb to carbon deposits from wear. I think my "adjustment" knocked the deposits loose and now it can function normally. I know this "fix" isn't permanent but it works for the short term until I can find another PPS.

bloomwcjkl

Thanks 911LE.

I have tried the "tap on the pedal assembly" a few times. One post said tap it 100 times with the handle of a screwdriver. :-)

Has anyone replaced their pedal position sensor assembly?

http://www.rockauto.com/en/moreinfo....57&jsn=8&jsn=8

Rock Auto has one in stock.

Johnhav430

Now I have a better picture myself,,,,on my Nissan, it's in the throttle body. And, my Nissan threw codes from time to time, and when the code was present, the rpms fluctuated, and being a physical cable linkage to it, pressing the accelerator to the floor multiple times would cure it, sometimes for 2 years. The reason I did not replace was a right angle screwdriver was needed which I do have, but the screw was frozen and stripped. If the LS430 follows the same concept, but places the TPS at the pedal, then it would almost stand to reason that if pressing on it a few times does not work, and if it's not a software glitch, then the physical device needs to be replaced. But I think on the LS430 it's like 10X the cost of the Nissan....

Bocatrip

John.....I at one time had a diagram of the numerous parts that are part of the drive by wire system for the LS430. I priced them at the time, and some were over the top expensive. I believe there were at least 4 or maybe 5 different parts. Throwing parts at this intermittent problem didn't seem cost effective to me, so I have lived with it and it has not become an overwhelming issue even at the current 130,000 mile mark.

Johnhav430

Yeah, that accelerator switch lists for over $600. On the Nissan, it was under $50, which is why I just let it go when the screw stripped and I still have the part in the box. Plus, one would think the vehicle is designed to throw a code if any of the components are defective....

911LE

The vehicle is designed to throw a code if any component in the system fails, except the PPS. The computer has no way of knowing when the PPS is bad. It only sees what signal the PPS is outputting and has to assume it is correct even if it isn't what you requested with the pedal. If the TPS or throttle plate motor start to go bad the computer can tell because the TPS signal won't match with what is requested by the PPS signal.

Galco

Having similar issues with my 2004. Since there are no codes, also suspect the peddle position sensor, but they are expensive for a trail and error approach of swapping parts until issue goes away. So, wondering if anyone tried to clean the potentiometer portion of the part show in this link from 911LE http://www.rockauto.com/en/moreinfo....57&jsn=8&jsn=8 as it looks like the cover may come off to expose the inner workings. The problem could simply be a dirty or oxidized switch that would benefit from a cleaner/lubricant like DeoxIT spray cleaner.

Has anyone tried to clean it? Or anyone willing to and report back?

bloomwcjkl

I have yet to replace anything dealing with pedal position sensor. I did work my pedal through range of motion tests. I did the steps where I turn the ignition on (car not running) and slowly push the pedal down and slowly release 3-4 times.

I also got under the dash and cleaned the parts of the pedal assembly. There is a lot of moisture and dirt that accumulates under there. I also tapped on the sensor area gently multiple times.

I guess I tried everything. I have not had a re-occurrence of the pedal dropping away from me since I did all these steps. I'm not sure if that is luck or if one/all of the steps combined helped.

I also ran a couple bottles of fuel injector cleaner through with tanks of gas. I guess if it starts to happen again, I'll redo the steps and see if it buys me some additional miles of driving.

romin88

If I am not mistaken, OBD2s can read your TPS sensors, current and learned. Get one of those cheap 2.1v OBD2 readers with good reviews ofcourse from ebay, download/buy "ELMScan Toyota" from Google Play Store, Go to Data List/Active Tests, you can get live readings from your pedal sensor and TPS sensors with engine off but ACC on, that'll put you one step closer, you can press the throttle/pedal and see if it registers on the ECU/OBD. If you do happen to have Techstream or Torque Pro, those can get readings too. Look for stuff such as.

Absolute Throttle Position – Actual position of the throttle
Relative Throttle Position – Amount of throttle opening
Accelerator Pedal Position D – The minimum opening usually about 5% above minimum.
Accelerator Pedal Position E – Similarly, the maximum position usually about 5% below maximum.

Personally I'd think it's a problem from your fuel system and running those cleaners seem to have done the trick, reason I say that is when you said while turning it does tend to happen presumably the fuel sloshes about in your tank? And as your slow down, ease off the pedal the pressure in your fuel pump, filter, lines drop hence again causing the problem to return, if it was a problem with any of the electronics your ECU will throw a code, and Lexus' are very good at that. Unfortunately for some reason older Toyotas and Lexus don't monitor fuel pressures(maybe they do but I am not sure?), while my old Nissan did, nevertheless, the app I told you about ELMScan Toyota seems to have Injector Volume controller which can increase your Injector volumes presumably causing the fuel pressure to increase/drop, try that too.