A week ago I was driving on a three laneinterstate at approximantely 70 mph. When I went to slow downby taking my foot off the gas pedal I realized it was locked in at 70mph. I thought the cruise control was on, but it wasn't. I put my foot on the brake, but the brake wouldn't go completely down;it just helped me slow downsome.When the mechanics looked at the motor they realized it was a mechanicalflaw.Has anyone had this happen to them, or know of any other cases?? If so please let me know.

 

Okay, without just a little bit more explanation, this means nothing. Surely they did not just let the explanation go at that? If they did, you need different mechanics. Can you elaborate on the problem?

 

Underneath the plastic air shroud (?) there is a throddle body with a large approximately 3-4 inch diameter circular butterfly valve that opens and shuts (like a choke) to let more air in the throttle body. On the leading edge of that circular valve is aproxiamately 1/4 inch wide half moon shape piece of metal that is welded on to the circular valve at the leading edge towards the radiator. I don't know what the function that piece of metal is, but apparently one side of the weld had broken off sometime back and it was attached only by the other side and apparently not flush with the circular valve anymore; therefore compromising the weld on the other side. Apparently the still attached but ****-eyed half moon piece of 1/4 metal was dangling far enough to hit a metal hose projecting into the bottom visible part of the trottle body and hadworn an inch long shinny groove in the hose. It appears as though hitting that metal hose finally cause the metal fatigue in the remaining weld and the half moon piece of metal broke off and got sucked into the intake runners and logged somewhere near the block, but did not sucked through the valve or damage the rotating asembly in anyway. By design that piece of half moon piece of metal should never touch anything and I can't conceive of any scenario that it should ever break. There is no stress on it at all in normal every day functioning. I'm just searching for answers.

 

lololol hubadewa, im sorry but what choke can you possibly be talking about? This is a Fuel Injected Motor, The Only thing next to the air shroud is the extension on the air intake. The only thing that opens and closes is the throttle plate itself, i own a 1997 S10 2 Door Blazer. Idk what your talking about or maybe were all missing something

 

It sounds like hes doing the best he can to explain what the mechanics told him. And from his description, its kinda easy to get what hes saying.

Lemme see if I can paraphrase

The diffuser on the backside of the butterfly valve in the throttle body got knocked partially loose, wearing into a hose or line inside the manifold. Then the diffuser ultimately let go, jamming the throttle fairly close to WOT. Luckily the diffuser got lodged somewhere inside the manifold before making its way to the valve train or cylinder heads.

So...sounds like he needs a new throttle body butterfly valve, and probably a fuel line or two inside the intake.

Pretty lucky nothing worse happened! I dunno how that sucker came loose though...I guess ALOT of carbon buildup?

 

I'm not a mechanic, just a single mother who had an almost death experience on the interstate. I have been sick since it happen realizing I could have hit those around me on the interstate, and or lost my own life. When it happen I saw a sign there was a wayside 1 mile ahead of me. I was riding my brake as far down as I could get it to go. I got off going 60 mph or so, all I could see were cars parked everwhere on the wayside. The break wouldn't go all the way down so I shifted it into neutral, the rpms went all the way up, and than I reached up and I shut the key off.

I was told todayby the mechanic itwas metal fatigue and they found the piece laying down by the valve.

 

Good thinking shutting off the engine!!! is the mechanic fixing it? Before you let him do anything, ask him for a list of parts replacing, cost, etc and post it here. Dont add getting ripped off at the shop to your list[:@]

 

I am glad you made it out ok. This is not a usual failure. I would have your mechanic get you another throttle body from the junkyard and then repair/replace what was worn inside the plenum. I do not recall there being fuel lines close to the throttle body inside, but there is the stand pipe for the EGR outlet into the intake. If this is what got worn into, I would not fuss over it at all.

 

Also glad your ok. You did everything correctly. Good job.

I also understood your explaination of hte problem.

I cut that piece of metal off my butterfly a long time ago. Best as I can tell its only purpose is to reduce engine noise. Appartently people would complain about the noise the air was making as it rushed pass the butterfly. They wanted a quieter engine.

 

To everyone who reply to my post thank you so much for your input. As you rightly said, the diffuser on the backside of the butterfly valve had a faint punch mark that you could see fatigued and tore the metal partically which showed up as an OLD tear in opposed to the smaller new shiny tear when it finally let loose and got sucked down onto the hose in the bottom of the trottle body keeping it open and explaining my run away vehicle. On upon the next start at the wayside, it than got sucked into the intake runner, and that is why we couldn't see it in the bottom of the trottle body. The diffuser is fairly stout metal and it took a prettystout wack to tear it.

To my knowledge this isn't something normally looked at in tampering cases and it is also something that never fails on its own. Hanr3 had to physically cut it offto remove it. Having an ex who is over six figures behind in child support and was sent to federal prison for income tax evasionin which I was the prime whitness, apparently inspire this clever tampering scheme which would be impossible for the police to place him at the scene of any future accidents. As a certified disel mechanic, his expertise crossed into gas engines or possibly his time in prison allowed him to learn from others like him.

I pray that forums like this keep that in mind for other unexplained run away vehicles because it truly is agenious way to ridone self of child support problems.

This creep who did this to my vehicle had died unexpectly at a fairly young age. And, "old good hearted" me was pressing the town detectives to find a cause for his death since none was listed on his autospy. This rings like a great mystery tale, but sometimes reality can be larger than life. Take care and God bless you all from "GMGAL"