Throttle Stuck Wide Open!

[Kai SRT10]

I was at the track today.
During my third track session, I was driving down the front straight at over 150mph with the pedal mashed to the floor. I lifted off of the throttle to begin slowing down for the turn at the end of the straight, and the car kept accelerating. The gas pedal was "floppy" and stayed on the floor instead of returning like it is supposed to. I put the car in neutral, and the engine began bouncing off of the rev limiter repeatedly until I turned off the ignition.

When I got the car to a safe spot, I popped the hood, and found that the throttle was stuck open. I initially thought that perhaps the cable had become stuck, but this was not the case. The throttle cable was loose, and the black thing in the picture (with the arrow) was stuck in the direction that the arrow is pointing. I wiggled it, and it returned to the closed position.

I was more than a little freaked out. I messed with the spring and worked the pedal a bunch of times, and it appeared to be working. I drove the car back to the pits, looked at it some more, and it still appeared to be working.

So, I took the car out for another session. Everything was going ok, but then, on my 3rd lap, when I was mashing the pedal on the front straight, it got stuck again. Same thing.

I looked at the throttle mechanism and can't see any damage. The spring seems to be in good repair, with plenty of tension. I took off the filter and looked at the throttle body blade to see if it is sticking. It appears to be ok.

If I had found something broken, I would feel a lot better. However, I can't see anything wrong with the mechanism, and the car seems to be working fine now (but I've been careful not to drive at wide open throttle.)

Anyone have any ideas as to what is going on? Anyone ever experienced a stuck throttle like this? It really put a damper on my day at the track (which up to that point had been going really well.)

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[Hostile]

Looks like the shaft is missing a throttle plate screw
allowing it to move some,note the scars on the
plate.


Skeeter

 

[Kai SRT10]

Looks like the shaft is missing a throttle plate screw
allowing it to move some,note the scars on the
plate.


Skeeter

If I understand you, there is supposed to be a screw where this arrow is pointing, right?

I wonder what happened to the screw. I hope it isn't bouncing around inside my engine.

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[ROCKET62]

Just went and took a look at my throttle body since my SRT is all apart and it defintely appears that you are missing a screw right where you have the arrow drawn. If you open the trottle with your hand, does the throttle plate move? Good catch BTW skeeter!

 

[Hostile]

That's what I'm talking about.If the screw
left with the engine running you might find
it in the bottom of the intake, one of your cats,
or stuck in the top of a piston(worst case)
The scars on the plate show it has moved at
some time.

Skeeter

 

[Kai SRT10]

This forum simply rocks!

Thanks 1,000,000 Hostile. I had not even noticed that the screw was not there.

 

[Bolt]

Great post!!!!!

I'm glad you did not get hurt.

Bolt

 

[Warfang]

Kai... give yourself a pat on the back. At 150 and stuck at WOT... u were calm enough to get yourself to safety. Had a friend that killed his car doing the wrong things in the same situation. Fortunately, at least he was ok.

Hope you get to the bottom of this.

 

[KEast]

Let us know what you find Kai.

One odd thing to me though. I agree 100% the throttle plate has moved, but did you all notice the area that appears to have been under the rectangular metal tab does not have a screw hole? Does anyone have a picture of the inside and outside of the throttle plate? It would be really good to this to confirm exactly how that plate is attached.



Kevin East

 

[Mopar488]

Now that is a scary thought, a Viper stuck wide open. A guy told me that he had a friend with a 96 B/W GTS stuck wide open and ran it under the back of a truck. I guess it happens, but I would hate to do it in a Viper.

 

[Viper Specialty]

Let us know what you find Kai.

One odd thing to me though. I agree 100% the throttle plate has moved, but did you all notice the area that appears to have been under the rectangular metal tab does not have a screw hole? Does anyone have a picture of the inside and outside of the throttle plate? It would be really good to this to confirm exactly how that plate is attached.



Kevin East

There are two screw holes in the plate. The plate slides into a cut in the bar, and the screws run through the hole and "pinch" the plate between them. Since it is missing a screw, the plate was able to swivel under WOT, and then did not allow the linkage to close again. EXTREME care must be taken with these screws. They should not only be loctited, but "destructively" prevented from moving- IE, punch the ends of the threads with a sharp metal punch so they cannot come out without effectively re-threading the screws on the way out.

Kai- I would highly advise treating this situation carefully. At a minimum, check the intake for the screw with a borescope, and run a compression/leakdown test. In addition, I would also advise using a borescope on each cylinder and checking for piston top damage, and pulling the cats to check for the screw. If ANYTHING looks amiss, pull the head and inspect further. If you find the screw, check it for signs of being pinched in a valve or smacked between a piston and head. If there is anything that points you in the direction of the screw getting pinched, get that head off ASAP and see if there is any damage. Much cheaper, faster and easier to put in a new piston, valve seat, valve or do a little maching now than deal with more damage later if a ring is now pinched, the screw is still lodged or a valve is bent...

 

[LittleFish]

Kai - very scary situation. Thanks for the story as one to file in the oh **** folder when it happens to us. Glad you are ok.