I was cruising along at 55 or so when I had to brake for an upcoming stoplight intersection. I had to floor the brake pedal to slow down and was afraid I wouldn't be able to stop in time. I saw my tach climbing despite the fact that I was braking and had my foot off the gas, so I immediately shifted into N. My engine promptly revved up to 5-6000 before I could kill the car. I waited a minute and pumped my gas pedal a couple times (thinking maybe it was a stuck throttle) and re-started it. In P, the engine raced up to almost 6 grand again before I could kill it - it sputtered to a stop. I took off my air cleaner and played with the throttle. No way it was stuck - it glided back and forth just fine.

I did notice was some thin white smoke slipping up through the margins of my throttle blades (a result of over-revving my hot engine or part of the original problem??). More came up when I opened the throttle.

I let the engine cool for a few minutes (it was up close to 200* b/c I had just jump-started a friend's car and it was hot out) and decided to give it one last shot. This time, it worked fine and has worked for three days.

I'm a bit scared to drive it like this - any ideas on what happened? The only other way I can see air getting into the TBI besides the throttle is the IAC valve. Is this a likely culprit?

 

hmm, could be thge IAC, but sounds more like a TPS problem to me. I'd wait fer someone with more experience to answer though...

 

Same thing happened to me once, the throttle spring got kinked, that was some scary $hit.

 

i really dont belive the iac could allow enough air to go threw to get to 6k and the tps only controls the throttle position telling how much fuel to put in but still it comes to the factor of not having enough air to get to 6k.

 

Same thing happened to me on the LG4, turned out the secondaries would stick wide open at random moments. I know this won't help you at all with your car being EFI, but it does happen in all types of engines.

 

I hope someone has an answer to this.the same thing happened to my buddies 91 tbi 305 car.He said it wound up over 6k before he could shut it down and it was not the throttle cable or throttle blade getting stuck.Only happened once though.

 

it isn't the IAC, I had a bad one and wide open it reved to about 2500rpm. nowhere close to 6000rpm, check your TPS though/and or wiring to it.

 

The only thing that could let in enough air to do that, even under no load, would be stuck throttle, or the brake vacuum line since that is what you pressed to start the whole scenario.

 

The TPS couldnt have that much of an affect on the engine... even if the TPS thinks the throttle is at full, the blades arent open anywhere near enough to support 6k.

 

it happened to me to but in my el camino. i was pullin into her driveway which is gravel and let of the gas to apply the brake only the gas pedal was still on the floor. i was spinin and shootin gravel all over the place and was caught like a deer in headlights and didnt know what to do. i almost ran into there garage after leavin a hole in the driveway that i had to fill cuz her pa had a fit. that was some really scary ****

 

this may sound dumb but do you have front floor mats? I've had this same thing happen to me and it turned out to be my floor mat moving down some and the gas pedal wedged completely floored. the engine revved way past 6000 before i could get it shut off. thats my 2 cents...

Eric

 

We had the same thing happen with my moms astro van. It ended up being the floor mat. She said it made all kinds of noise when she put it in neutral and coasted to the side of the road. Got to diggin around and the thing doesn't have a rev limiter so it was wfo for about 45 seconds. Still ran like a charm.

 

same thing has happened to me twice, the first time it was the cable and the second time the floor mat...with the floor mat i figured it out before i ended up in trouble cause i was on the highway accelerating to get on and it got stuck so i had time to think.....i don't see how that could happen without one of the things that people have mentioned being the culprit

 

That sort of thing heppened to me once. It was raining and this moron in a truck pulled out in front of me so I had to slam on the brakes, well then I hammered it to pass him and the throttle stuck at WOT. Well since it was raining, I started sliding all over the road. I had to hold the brakes almost to the floor and then kill the engine and roll into a parking lot. The secondary lockout tang on teh carb was messed up and causing the throttle linkage to get stuck. I removed the lockout tang and problem solved.

 

I really don't think it's my floor mat, although I obviously can't say I'm 100% sure, but I remember pumping the gas to feel if the throttle felt stuck and it came out freely... it's kinda scary, driving around like this.

Anybody have a guess as to what the white smoke whisping out of my TBI was? Just a result of over-revving the engine? Thanks for the replies!

 

That same damn thing happened to me!!! I came to a stop sign, pressed on the brakes- and the engine kept pushing the car forward... I slammed on the brakes, and sat there, wondering what to do... then I looked down and my floor mat was really far forward. I pulled it backwards, and the engine stopped rev'ing up. Geez.

On my dad's old Oldsmobile, with the 2.8 MultiPort front wheel drive motor, the bushing for the throttle linkage (on the TB) wore out. His gas pedal got stuck because the butterfly valve was cocking sideways, and the return spring wasn't strong enough to return the TB to a closed position. The mechanic "re bushed" the bushing, but it failed again a few months later. A $30 TB out of a junkyard 2.8 MPFI fixed that.

 

This happened to me last night. I was driving my transam and was at a light.. after shifting into first it was fine...... when i shifted into second it took off like a bat out of hell (but was VERY smooth) car never took off like this and sort of left me in surprise ... then I realized the tach was quickly climbing at approx. 5800 RPMS ( in neutral ) without me pressing the gas pedal. I felt the gas pedal and it wasn't depressed.. so i hit the clutch pedal in and out and it stopped the revving...... any ideas why/how this could have happened would be appreciated thanks was pretty scary to say the least.

 

I had same thing happen, on the way home from work one day in bumper to bumper traffic at about 5pm, not a fun predicament, haven't had driver's side floor mats since . It's not fun standing on the brakes at wot in a 350 at 60miles an hour in rush hour traffic. Put her in neutral saw it rev up was like oh sh*t and then finally realized what was goin on and turned the car off and pulled off to the shoulder. Felt like it took 5 minutes but was only a couple seconds. Quite a nerve wracking experience. WOT is only fun when you want it to happen.

 

I thought this only happened to me!!

I had the floormat thing happen too..

also I found if I wear boots or bigger shoes.. One time I
was driving with boots, and I went to hit the brakes and my foot
got stuck and I couldnt get it unstuck, I had to use my left
foot to hit the brake... scared the **** out of me!

 

Don't forget to check out the power brake booster - a massive vacuum leak. I'm guessing it is pedal/linkage related, though. An IAC shouldn't pass enough air to hold much more than 3,000 at best, and not even that in gear.

 

Probably fuel vapors