Hey all, I am in desperate need of some help with my 2000 Rx300 (FWD) regarding the car suddenly accelerating on its own.

I had been driving for roughly 10 minutes at a speed of 55mph when the car jerked forward and hit about 3000 rpm on its own with my foot away from the gas pedal, the rpm started going up more as time passed until it was near redline. When it first started i had just assumed I accidentally engaged cruise control, so i toggled it on and off a few times just to be sure but that didnt stop it, I then checked to make sure there was nothing blocking the pedal and that the floor mat wasn't in the way but that wasn't it either. After looking for every possible cause and finding nothing, I pushed on the brakes as hard as i could but they acted like they weren't doing anything and slowed me down by only about 15mph fully depressed, I then engaged the emergency brake fully but that didn't slow me down at all, by this point the car was just under red line and i had reached 85mph. I finally just had to pull the key out and coast to a stop and even then the brakes were not working properly.
This had all happened within a span of about 1 minute.

The first thing I checked was the throttle cable and nothing seemed out of the ordinary, it wasn't sticking or anything. Now as soon as I crank the car it immediately shoots all the way to redline and stays there. I have no idea what could have caused this, I've had the car for nearly a year and never had any problems other than a small battery drain that kills it if it sits for a few days. Is it the throttle position sensor? Or could it be the electronic throttle control if these cars even have that? Maybe something cruise control related ?

I apologize for the rambling nature of this post, I'm still just a little shaken up. Thank you ahead of time for your help

 

I've put over 300,000 miles on various RX300 and it never happened to me, nor do I recall anybody on this message board describing it. Serious problem; if no obvious explanation appears, best to take it to a dealer or competent independent mechanic.

 

https://www.carproblemzoo.com/lexus/...n-problems.php

Im not 100% sure of the legitmacy of the statements from this site, but some of them are the exact issue i experienced.

This one in specific is nearly identical to what happened to me.

"My 2000 Lexus Rx300 had an unexplained sudden unintended acceleration where the vehicle almost killed me and my son. I was driving residental backroads by my house, accelerated slightly to get up a hill and that's when it took off. The brake pedal was unresponsive, the emergency break was unresponsive, I pulled the floor mat out for good measure, nothing worked, it kept accerating at a high rate until I finally slammed it through gears to "park" to get it to a stop. I had it towed to the Lexus dealership, where the tow truck driver even told me when it started the car to get it up on the truck, after being turned off for over 12 hours, it was still red lining the engine, and even lurched forward but because the car was in park, it didn't crash into the back of the tow truck. Lexus investigated the car and did absolutely nothing. They wouldn't tell me why it happened. I demand an explanation and a replacement vehicle - one that doesn't have a history of having sua problems. I fear for my life everytime I have to drive this vehicle."

Definitely planning on getting it to a mechanic asap, was just hoping to have a ballpark idea of what the cause might be. Thank you for the response

 

Glad that you are living and not hurt [along with no injury and loss of property of others].

Before we get into technical details, please have your vehicle towed to a reputable shop and let them diagnose or try to recreate the situation. Advice over the net is fine, but what you went through and if the problem is not rectified, life and property is at stake.

Now the panic situation is over, please accept my critique as Monday quarterbacking and hopefully readers can benefit from it too.
Brakes, gas and steering at all important.
when the engine is shut, you loose power assist on braking and steering. Engine shut off [run -> acc] should be a backup situation when the engine keeps revving up [your case]

"Pulling the key" is a bad move as it locks the steering. Manufacturers have a safety feature [push the key in RX].

First gen RX is driven by throttle cable and cruise cable. [not electronically driven]. One of the two can rev up the engine under normal conditions. Spring mechanism is there to pull back the throttle .. it can be stuck but it does not give more gas on its own.
Good working brakes on RX can overcome the power generated by the engine. Exception is when they got hot. With normal (warm) pads, they should stop the vehicle even when the gas and brake pedals are depressed. Applying brakes should disengage the cruse.

In unintended acceleration the cruise if engaged (accidentally or on its own) there needs to be some way of telling it to accelerate (like resume).

Final word:
Please do not try to fix the vehicle by doing anything. Tell the repair shop NOT to fix the problem but analyze it. I say that as per your statement the vehicle is running at WOT (wide open throttle). Right now the vehicle is in "FAIL" state and a good meaning checkup can pull it out of the fail state. Once in good hands, they can zero into the problem and then a cure.

At the end, all you may need is a throttle body cleanup [something holding the butterfly wot].

Salim

 

From your description, "...i had reached 85mph. I finally just had to pull the key out and coast to a stop...".

Given the shift interlock, how were you able to pull out the key without shifting into park first?

And wouldn't shifting into neutral have made sense?

 

Your car also lurches forward in park?? You realize your story is full of things that mechanically and historically never happen?

 

I do plan on having it looked over by a shop in the next few weeks, and you're completely right regarding it being a life at stake situation, I have no intentions of continuing to drive it even if i was able to.

Yeah, in retrospect I stopped it in just about the worst way possible but having never been in a situation like that I went right into panic mode and just intinctively went for the key. The weird thing to me though is that the steering wheel did not lock with the key removed, I didnt have power steering of course but was able to turn the wheel no problem. Another thing, is that the car was re-keyed prior to me owning it so I do not have the stock ignition key, I'm not sure if thats what allowed me to fully remove the key while still in drive or not but there was no resistance when removing it, but the ignition has definitely been tampered with.

Well since they don't have ETC that at least narrows it down for me a little bit, thank you. This really seems to me to have something to do with the cruise control since as you said the throttle could have gotten stuck but it wouldn't have given it more power like what i had experienced.

Thank you for the concern, I fully plan to follow your advice and leave it to a shop to figure out.

and, carguy07 what you're referring to is not my experience but someone elses statement i had found that was similar to mine, sorry for the confusion.

I am also planning on trying to take some videos of starting the car tomorrow, so I'll link it here when i get the chance

 

I'd also suggest a potential culprit I don't see mentioned - your floor mats. Are you using OEM floor mats? Are they secured in the lock holes in the floorboard and are they well clear of the accelerator? Do you have just one set of mats in the car or maybe rubber covers laid over carpet mats?

 

OP wrote: "I then checked to make sure there was nothing blocking the pedal and that the floor mat wasn't in the way but that wasn't it either. "

 

What he wrote was not specific enough which is why I asked what I did.

Massive recalls from Lexus and unintended acceleration lawsuits against Lexus in the early 2010's all addressed this specific issue. Owners were not locking down the floor mats with anchors, owners were putting two sets of floormats in their car, etc. Un-anchored floormats move and can jam up against the accelerator mechanism and problem is they can shift when you are driving and shift back when you get out so you don't even notice they are an obstruction.

May not be an issue at all in his situation, but OP should look for that specifically since it is a widespread and recognized problem. It's the easiest to identify and remedy.

EDIT I did just see in a subsequent post though I missed reading where he said pulled the mat out entirely, so maybe not a related issue for him.

 

You weren't referring to Post #3 by any chance, were you? That entire paragraph is (apparently) the story of another person the OP has found online with the same issue.

OP, I concur with Salimshah, that it was very fortunate no loss of life or limb occurred in what happened. I very much hope you find out what it is, as I can also say that I have never heard of an RX vehicle with sudden unintended acceleration (unless there is the throttle cable binding or sticking somewhere? I know you already said that isn't the case). I think the assessment of DaveGS4 may have merit, and it could have been the floor mat all along. Even the Owner's Manual I have specifically warns that the Driver seat floor mat poses the hazard of covering the accelerator pedal and causing unexpected acceleration if not fixed to the floor correctly using the hook.
Awaiting any news from the shop..

 

Oh yeah I was, good eye!

 

My concern for OP at this time is that no one should mess with the vehicle as the good thing for him is the vehicle is still behaving as WOT (could be half way as there is no load). On the other hand if someone bumps/taps/etc and releases the WOT condition, his issue will be chalked as "not reproducible".

On personal note: I have experienced (many years ago and not in any Lexus/toyota vehicles) a total brake failure. I almost soiled my pants and luckily I was at low speed and made it back to the shop (which did the shoddy brake repair) with throttle and steering.

Why I share the war story is .. under stress conditions the human mind behaves very differently. It goes to OPs credit that he did what he did and had no damage. Lets hope for his sake we find the underlaying problem and his confidence is restored.

Salim
PS: We all need to go through various scenarios to train ourselves. Some say that a good percentage of vehicle in water deaths happen as the occupant failed to release the safety belt.

 

Wow, several wows - especially the seat belt thing. I too had sudden brake failure almost 20 years ago to date. My wife was driving and the Man and his Son were looking out for us that day. The shop was unable to duplicate the issue and upon discussion we believed it was due to having given someone a jump start just prior to the event. We were doing 70 mph when it happened - exiting the Interstate. No brakes, NONE! She stepped on the emergency brake and we went thru the light at the top of the exit ramp. By the time we got stopped the back brakes were smoking. I never trusted that vehicle again and have NEVER jumped another car with any of my vehicles.

 

I have a 2000 Lexus Rx300 and this exact same thing happened to me. The car has 258,000 miles but had no prior transmission problems and no check engine light. It's been the best car I have ever owned

Long story short, On Saturday 9-10-2022 I pulled into my driveway and stopped. As soon as I shifted the car into park the car took off forward full throttle (it went right through my garage door). I stepped on the brake and it keep going full throttle (like I was trying to power brake it). The only thing that stopped it from continuing to go through my house was the fact I pulled the key!

I have owned this car for over a decade and am still mind blown by the experience. I was very lucky and probably ended up with 1200 in damage (garage door etc) but I won't put the key back in the ignition. The shifter is still in park but when you move it you can tell it is not shifting the gears. The light in the dash is saying it is in reverse.

Even though this costs me a bit of money and a huge headache, I feel lucky this didn't happen somewhere else. It could have easily killed someone or caused way more damage. If I wouldn't have pulled the key I can't even imagine the house damage I would have.