'97 Ltd Sudden Acceleration

steanson

steanson

Member
Well, what I've only heard and scoffed about until now, happened to me this morning in 6 O'clock traffic on LBJ Freeway (the highway loop around Dallas).
Let me preface this with...I'm not looking into a long debate about operator error, floor mats, etc...AND I'm not seeking any legal recourse. I just want to document what happened, and see if there is anyone else that has experienced this unusual and terrifying phenomenon.
First, what I got: (go away, grammar police)
-1997 Toyota 4Runner Ltd...second owner.
-221,000 miles, original motor; no record of any major engine repairs.
-Been running rough for better part of 2 years...changed the plugs a year ago, problem got better.
-Burns oil; must need rings. #3(?) Cylinder (middle driver side) plug was drenched in oil. Every so many months, Upon startup, it blows enough smoke out the pipe for about 2-5 minutes...dense white/gray smoke that looks like the set of a Whitesnake video...or Navy SEAL Team 6 dropped smoke for cover.
***all that, to me, is unrelated***
Now, what I THINK may be related:
-Brakes are BAD. Like, the light comes on intermittently, more regular/steady now than before.
FACTS:
Was driving home from a long shift at 6am. Weather change...mid 40's (opposed to 80's-90's.
-I was passing and changing lanes to exit, and had it punched.
-NO FLOOR MAT interference.
-NO Cruise Control activation at time of acceleration.
-I have a blown fusible link, so NO power plug access, SO, I had my iPhone plugged in to a "Goal Zero battery power supply". *I don't think e-interference has a part in a problem on a '97, but who knows.
-Check engine light never even blinked.
-After flooring it to pass a truck, IT TOOK OFF. LIKE, BALLS TO THE WALL. Traffic was appx 2-4 car lengths @ 55-60mph. Yeah, I know...
-As soon as it revved into upper RPMs with my foot off the gas, I first put my foot under the pedal and pulled back to see if it was stuck on something. NOPE.
-I was approaching a construction exit, one lane, detour type ramp, behind heavy braking cars...so I STOOD ON MY BRAKES. HARD. WITH EVERYTHING I HAD. NOTHING. (Bad brakes, remember? BUT they still stop perfectly under normal conditions.)
-NOTHING. I tried to flutter the accelerator, but all it did was redline.
-Now I'm in the exit, (this happened in the course of an 1/8 to 1/4 mile), and commuter noobs are freak-braking because, well, they are scared of the "chute" exit.
-Shift to NEUTRAL, Redline, Quickly KeyOff, then key back on.
-Mind you, up until this, I was standing on the brakes, AND pulling hand lever, and thinking "I'm going to smoke my brakes to FAILURE...THEN what?!?"
-It began to chug along, and started to rev again, so I tapped the cruise control (why not? what else?), and it began to roughly return to normal. Now on the Dallas North Tollway, I cautiously made my way to my exit, and at the redlight shut it down, waited a second, then started it up again. All was normal (CC off).

-No mods, except air-silencer removal, K&N, and open top airbox (poor man's deckplate mod).
-NEVER had a problem like this, and have had it since '06 with 77,000m.
*****
I had to pick my shredded leather seat out of my hiney after this incident.
So, brainstorming time...any ideas? I could scan the codes, but I'm certain the Check Engine Light never even flickered.
First off...Sell a kidney and Replace my brakes. (Sad when a paramedic district supervisor has to live paycheck to paycheck) Maybe upgrade? Tips?
Now, SOMETHING I READ A BLURP ABOUT:
Possible Vacuum issues with bad brakes...like, when brakes are bad, vacuum to
throttle body is compromised...
Thanks in advance for any ideas. I LOVE this vehicle...am never going to sell it.
 
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Sounds like your cruise control was too blame and maybe thought you were slowing down a ton and tried to compensate.
 
My first thought is that you have either have some type of electrical short or mechanical failure that led to an inadvertent/uncommanded acceleration actuation of your cruise control. If I was in your position, I would disconnect the cruise control actuator mechanical linkage from the throttle body until I find an obvious problem.
 
Well that sucks if it did truly happen.. Not saying your lieing, but I find it hard to believe on a completely unrelated vehicle WITHOUT the stupid "drive by wire system". Yours is mechanical, it is impossible for your vehicle to accelerate without stepping on the gas pedal because there is a cable connecting the pedal to the throttle, NO electrical wires/sensors to control the throttle valve.

So if this did happen, that sucks and I have no idea or how that could possibly happen. Unless cruise control to blame.

But what I do know is its almost impossible to stop a vehicle under full throttle using the brakes because the "brake booster" uses engine vacuum to assist you in stopping. When you are full throttle, that engine vacuum is dramatically reduced to the brake booster. Hence why you couldn't stop.
 
I'd check to see if you can get the throttle to stick again while in park at idle revving it. It's most likely you have a sticking throttle plate or cable.

As for your brakes.... The engine produces its most vacuum at idle/low rpm and your system is vacuum assisted like most. This works well under normal conditions because you are typically off the throttle when braking but in your scenario the throttle was open reducing brake assist.

Its a simple system and all the Toyota sudden acceleration issues you are referring to are entirely different. That being said I've seen fraying cables and dirty throttle bodies cause this on number of vehicles of various makes including Toyota.
 
5vzT4R said:
Well that sucks if it did truly happen.. Not saying your lieing, but I find it hard to believe on a completely unrelated vehicle WITHOUT the stupid "drive by wire system". Yours is mechanical, it is impossible for your vehicle to accelerate without stepping on the gas pedal because there is a cable connecting the pedal to the throttle, NO electrical wires/sensors to control the throttle valve.

So if this did happen, that sucks and I have no idea or how that could possibly happen. Unless cruise control to blame.

But what I do know is its almost impossible to stop a vehicle under full throttle using the brakes because the "brake booster" uses engine vacuum to assist you in stopping. When you are full throttle, that engine vacuum is dramatically reduced to the brake booster. Hence why you couldn't stop.
Click to expand...

The cruise control actuator connects directly to the throttle valve. It is entirely plausable that there is a short somewhere in the "accel" command circuit. I would disconnect the cruise control cable asap.
 
5vzT4R said:
But what I do know is its almost impossible to stop a vehicle under full throttle using the brakes because the "brake booster" uses engine vacuum to assist you in stopping. When you are full throttle, that engine vacuum is dramatically reduced to the brake booster. Hence why you couldn't stop.
Click to expand...

This makes sense...like I said, I was mashing the brakes through the floorboard, and it felt like I was on a rollercoaster...it just kept accelerating.
Worst part was looking for an "out"...traffic was moving at appx 60mph, and in the construction, not even a shoulder to pull off on.

I mark it up to Karma...there was a 4 car fender bender 10 miles back in the left lane, and the fools were standing around jawing back and forth rather than removing their vehicles to the exit...so I rolled down my window and kindly asked them to get their a**es off the highway.
 
p5150 said:
The cruise control actuator connects directly to the throttle valve. It is entirely plausable that there is a short somewhere in the "accel" command circuit. I would disconnect the cruise control cable asap.
Click to expand...

I'm not sure. Just read somewhere when I got home. My understanding was, if I've got bad vacuum, and my brakes are already crap, ...oh, Hell, I don't know what I'm talking about. Electrical and vacuum troubleshooting baffles me....another reason I dumped my 90 Mercedes SL. It was all electrical and vacuum, and whenever I tried to work on it...I would raise the hood or remove interior panels and just stare at it like a village idiot.
 
Going to look into disconnecting the cruise control...I don't think I've ever used it...even driving back and forth to the coast. (long drive).

Although, there is a SICK, DEMENTED part of me that wants to replicate the problem...albeit not in 6am rush hour traffic. Maybe I should quit driving pedal to the metal...I'd probably get more than 13 MPG.
 
Well you said it continued to redline when taken out of gear. That means that the throttle body was open. Only two things can force the throttle open: your foot and the cruise control actuator.

You should either disconnect the electrical connector on the actuator or cable from the throttle body before you get in a serious wreck.

I'm a certified ASE mechanic and have an FAA A&P license also. I fix airplanes and cars. If that happened to me I wouldn't drive it again until I knew for sure that the cruise control actuator was disabled.
 
And if a mechanic cant help you find an obvious problem with it after inspecting the wire bundle and buttons, I would at the very least put a new cruise control actuator in it before I attempted to use cruise again.
 
Make sure your throttle cable isn't starting to fray a bit. It's funny you made this post, I work for Infiniti and have an older QX4 in here, which is a small 4runner sized suv, with a throttle sticking due to a frayed throttle cable. The QX4 setup is VERY similar to our 4Runners as well.
 
how clean is your motor? im gonna bet you have a bad return spring or a corroded axis on the return spring or in the shaft to the throttle plate. take some type of penetrating oil and spray your throttle linkage and cables. what you described was not sudden acceleration but the lack of deceleration once you let off the gas, this tells me your throttle stuck open. i have had this happen on a couple vehicles. one was my old malibu, and that was scary, it was a strait line car and had no problem of laying 50+' or rubber, and when that car stuck wide open i was along for the ride. it was none stop fishtailing till about 60mph and then i was able to shut if off after i got it back under control... it was an interesting experience

this was the beast;

lingenfelter wagon by isaacyocum, on Flickr

snapon wagon burn out by isaacyocum, on Flickr

IMG_1109 by isaacyocum, on Flickr

IMG_1107 by isaacyocum, on Flickr

the other one was an pontiac grand am, that one i blew the motor on -no loss, besides not my car lol
 
the kid said:
how clean is your motor? Im gonna bet you have a bad return spring or a corroded axis on the return spring or in the shaft to the throttle plate. Take some type of penetrating oil and spray your throttle linkage and cables. What you described was not sudden acceleration but the lack of deceleration once you let off the gas, this tells me your throttle stuck open. I have had this happen on a couple vehicles. One was my old malibu, and that was scary, it was a strait line car and had no problem of laying 50+' or rubber, and when that car stuck wide open i was along for the ride. It was none stop fishtailing till about 60mph and then i was able to shut if off after i got it back under control... It was an interesting experience

this was the beast;

lingenfelter wagon by isaacyocum, on flickr
Click to expand...

jump it!
 
the kid said:
how clean is your motor? im gonna bet you have a bad return spring or a corroded axis on the return spring or in the shaft to the throttle plate. take some type of penetrating oil and spray your throttle linkage and cables. what you described was not sudden acceleration but the lack of deceleration once you let off the gas, this tells me your throttle stuck open.
Click to expand...
agreed,

I would take a close look at the cables, and cam. to make sure there isn't a frayed cable, or maybe even that the cable didnt snag on something after the WOT pass.
 
Thanks in advance for any ideas. I LOVE this vehicle...am never going to sell it!""

Wow! I'd sat get rid of that thing, if my 97 limited put me in that situation and u couldn't trust it whether I found the prob or not. If your neighbor or friend was living with you and pulled a gun on you unexpectedly putting you or family at rusk, would you get rid of them or try to understand why they did it and have them checked out? I know what I'd do!
 
Last edited:
On a smaller note, as for your brake light flashing intermittently on you, check your fluid level in the master I bet your just low (probably due to those thin pads..so change em out!)
 
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