A Case of Unintended Acceleration; Why Some Drivers Panic

Ronnie Schreiber
by Ronnie Schreiber

I recently did something stupid that put me in a dangerous situation, but it taught me a lot.

Ever since the days of the Audi 5000’s unintended acceleration issue (yes, grasshopper, Toyota wasn’t the first automaker to face the matter), I’ve wondered something.

Even if the problem really is a mechanical or electronic defect causing the acceleration (I’m in the skeptics’ camp on that, the component between the seat and the steering wheel is likely the defective one), why didn’t the drivers just shift into neutral and use the brakes to slow and then stop the car?

The braking system on every car sold in North America for the past 40 years has been capable of slowing and ultimately stopping the car under full throttle. That’s how I managed to recently safely stop my Saturn sedan when the engine started to rev uncontrollably. The situation gave me insight into what’s going through a driver’s mind when that happens, and perhaps some understanding why folks end up getting into accidents when it does.

Not far from my home in suburban Detroit, I was driving south on Southfield Road, where the road becomes the onramp to the northern end of the southbound Southfield Freeway. As I accelerated from the last stoplight, I felt something unusual from the gas pedal. By the time I was on the ramp I realized something was keeping the throttle open. I fiddled around with my foot to make sure it wasn’t a water bottle or something else on the floor jamming the gas pedal as I considered that I was going too fast for the heavy traffic, too heavy to try to stop completely and, in any case, there wasn’t a shoulder there for me to stop.

The tachometer was right around 4,100 rpm. The SOHC Saturn 1.9 liter motor isn’t exactly gutless, but you really have to keep it above 3,000 rpm if you want to accelerate briskly —4,100 is certainly in the sweet spot in the power band.

I tapped the brakes and while they kept the car from accelerating, the pedal felt unusually hard. That’s probably because I’ve never braked under heavy throttle before. That’s when I realized it was pretty serious; no panic, but things definitely weren’t cool. I rode the brakes, figuring it was confusing the driver behind me since I wasn’t slowing much. Then I shifted into neutral, which at least kept the car from accelerating more and kept the brakes from fading. By then I had to make a decision, stay on the freeway or pull off at the first exit, which meant getting over in a hurry as it was approaching quickly.

With the transmission in neutral, the engine started to oscillate up and down a couple hundred revs, almost like it was hitting a rev limiter, which this engine doesn’t have and in any case, that’s way below the redline so I wasn’t worried about throwing a rod or some serious damage. Still, something was not right and I had to get the car safely stopped. As soon as I got up the ramp, I turned down the first side street, and with the car still in neutral I stopped it, shut off the ignition and then shifted the transmission into park. Dropping it into park at 4,100 rpm probably would not have been good for the transmission’s parking pawl, or the transmission mounts.

Looking down into the footwell, I could tell that there was nothing obstructing the gas pedal, so I got out to check under the hood. I caught a whiff of hot metal — likely the brake rotors — as I walked to the front of the car. When I opened the hood I discovered that I had done something stupid the day before which caused the problem.

This summer I did something that I never thought I’d ever do. I fixed an automatic transmission. I’ve done a fair amount of wrenching on cars, up to and including rebuilding engines, but as far as I’m concerned ATs are a mix of planetary gears (which I don’t quite understand) and voodoo.

However, according to a variety of Saturn enthusiast sources and YouTube instructional videos, the problem my Saturn was having — slamming into reverse and most forward gears — was almost certainly due to a worn valve body, and the valve body sat right on top of the transmission, making the repair a fairly straightforward remove-and-replace job once you get the battery box and air intake out of the way. The rebuilt valve body was a couple hundred dollars, but I figured doing it myself had to save at least that much. Automatic transmission work is never cheap when you have to pay for it.

Post repair, the transmission was working fine and shifting smoothly, but I noticed a fluid leak and some gearbox noise from the low fluid level. My first thought was that I shouldn’t have reused the valve body cover gasket like all the online instructions told me to do. Then, I noticed the leak was from the general vicinity of the spin on transmission filter. As mentioned, I’m no novice as a shade tree mechanic. I have a pretty good idea off how hand tight a spin-on filter like that should be, but I guess I didn’t have it on there tight enough because it had walked itself back about a full turn. I retightened it, gave it another quarter turn just to be sure, and added the half quart of fluid I had in the car. That fixed the leak and reduced the noise.

This past Sunday, prior to driving down to the time warp that is Powell, Ohio for the mitzvah of visiting the injured, I added another half quart of Dex III/Merc ATF, to top off the transmission. That quieted things down back to normal.

After my little episode of unintended acceleration, once I got the car safely stopped, I discovered that when I went to put away the funnel I was using to get the fluid into the dipstick/filler tube, I had forgotten to put the dipstick back. I don’t know how it stayed where it was on top of the engine for almost 400 miles of driving, but by the time I was entering the Southfield expressway, the plastic pull-ring on the end of the dipstick had managed to work itself around part of the linkage for the fuel injection throttle body, preventing it from returning to the idle position.

I disentangled the ring from the linkage, put the dipstick back in the tube, wiped the grease from my hands, restarted the car and went on my merry way. Looking back, though, I can understand how some drivers might panic, no matter the cause of the unintended acceleration. I’m relatively knowledgeable about cars, but it took me about a quarter mile to figure out that the engine was racing. If not completely out of control, the engine was running at a high enough rate to be going too fast for conditions. Then, when I used the brakes, they felt very hard — almost failed-master-cylinder hard. I’m sure that would disconcert most drivers and possibly cause panic.

Additionally, since the Toyota UI issue arose, I’ve reviewed a few cars that have push-button keyless start, or unusual shifter controls. I’ve given some thought to how to find neutral and shut off the ignition if needed in every car I’ve driven for the past couple of years. Shifting into neutral when the Saturn started to run away was natural for me, but I’m not sure how many drivers in an unfamiliar emergency would think of it. As it happened, steering a car at highway speeds in neutral felt kind of weird. We’re not used to freewheeling.

Outside of insight into driver psychology, this incident has reinforced a lot of what I’ve previously believed about unintended acceleration. It’s not very likely to happen, but when it does, it’s probably the result of a traceable mechanical or electronic issue. When it does happen, shifting into neutral and using your brakes will undoubtedly slow the car and keep you safe.

This unintended acceleration incident has also reminded me of the first rule of repair: Make sure you put all the parts back in. I’m not likely to forget about a dipstick like that again.

Ronnie Schreiber edits Cars In Depth, a realistic perspective on cars & car culture and the original 3D car site. If you found this post worthwhile, you can get a parallax view at Cars In Depth. If the 3D thing freaks you out, don’t worry, all the photo and video players in use at the site have mono options. Thanks for reading – RJS

Ronnie Schreiber
Ronnie Schreiber

Ronnie Schreiber edits Cars In Depth, the original 3D car site.

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  • Mechaman Mechaman on Oct 23, 2015

    I owned one of the mythological Audi 5000's awhile back: the car was , by that time, a beater, albeit a reliable one (favorite memory, starting other people's car with that huge battery under the seat). One thing I noticed was that the car tended to 'jump' a bit forward when it started - I took that to be the age and wear on the car. But the pedal arrangement did make it too easy to step on the gas when you thought you were on the brake...

    • See 1 previous
    • RideHeight RideHeight on Oct 24, 2015

      @sgeffe I'm sure we would all be forgiving if you accidentally hit us or ours in the interest of cleaner air. It's our duty to Gaia.

  • MWolf MWolf on Oct 30, 2015

    I had unintentional acceleration occur twice in two separate vehicles. In my 1990 Deville, I simply kicked the throttle and it unstuck itself (just needed lubrication). The other was a 94 Explorer. A stupid floot mat ended up on top of the accelerator. I mamaged to reposition it with my heel, pull over and throw that damn mat to the back seat. Both were unsettling, but not enough to cause me to wreck. I generally understand when something doesn't feel right with a car before it reaches the point of an accident.

  • FreedMike Off topic, but folks, this site is not working well for me from a technical standpoint, and it doesn't matter if I'm using my phone, or my computer (on two different browsers). It locks up and makes it impossible to type anything in after a certain point. Anyone else having these issues?
  • Syke Kinda liked the '57, hated the '58. Then again, I hated the entire '58 GM line except for the Chevrolet. Which I liked better than the '57's. Still remember dad's '58 Impala hardtop, in the silver blue that was used as the main advertising color.
  • Dartdude The bottom line is that in the new America coming the elites don't want you and me to own cars. They are going to make building cars so expensive that the will only be for the very rich and connected. You will eat bugs and ride the bus and live in a 500sq-ft. apartment and like it. HUD wants to quit giving federal for any development for single family homes and don't be surprised that FHA aren't going to give loans for single family homes in the very near future.
  • Ravenuer The rear view of the Eldo coupe makes it look fat!
  • FreedMike This is before Cadillac styling went full scale nutty...and not particularly attractive, in my opinion.
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