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When my son first got his 1994 Camaro RS, there were two incidents where his engine stayed in WOT and he lost control of the car. The first time it happened, the car thankfully stalled in a deep patch of sand off the road. I investigated and thought perhaps because his small carpet seemed wedged pretty far forward and wound up under the gas pedal that this is what happened. But I found nothing definitive and chalked it up to that circumstance as being the cause of problem.
The second time it happened many months later. But this time he was in heavy traffic and somehow, after his brakes faded and failed, he managed to run completely off the road, plowing up a row of bushes instead of cars and people, badly damaging his front bumper, hood, and the drive shaft cross member which I replaced.
Thankfully, neither he, nor anyone else was harmed. But this time though, I did a better job of investigating and finding the actual cause of the problem. It was such a simple thing, but it could have been disastrous. Here is what I discovered:
(1) Checked under the dash above the gas/brake and found no carpet/cables binding.
(2) Followed the dual cables from the firewall to the throttle body (no binding).
(3) Unbolted and removed the plastic shroud around the cable hook-ups on the TB and cycled the double spring mechanism time and again, I could find nothing wrong.
(4) Removed the throttle body and serviced it from top to bottom, with two new sensors installed.
(5) Upon re-installation of the TB and cables, I was slipping the air handler hose around the inlet of the TB when I spied what actually went wrong...
(6) Whoever had last serviced the unit prior to the Camaro changing hands had REVERSED THE STAINLESS STEEL CLAMP on the air tube from being positioned outboard (left side of TB when facing the engine) and opposite from the area of the double spring actuated, dual cable bell crank on the right side of the TB, facing the engine!
(7) When improperly reversed, the hex-head of the S/S clamp is moved into a position that allows a right angle piece of the bell-crank mechanism to move up over the hex-head and get stuck on top of the bolt head. So whenever the gas pedal is pressed nearly to the floor, even with the strong dual springs working properly while trying to return the throttle to the neutral/idle position, it simply stays at the WOT position. When this happens, the cables go completely slack and the S/S clamp screw holds the throttle in a WOT position until physically jarred loose or pulled free by hand.
(When this occurs under normal driving conditions, nothing short of turning off the ignition key (if even possible) can be done to stop a 'Runaway" condition from happening.)
Whoever had serviced the car must have completely removed the clamp which is normally held in place with the hex-bolt on the left side by a pointed rubber rivet poking through a small hole in the bottom of the S/S band. Some Yo-Yo had actually slid the entire clamp off of the air tube ...and put it on backasswards with the rubber rivet stuck back through the hole in the bottom of the S/S band! The oval top hole in the clamp where the air pipe fits in gives no indication if it is turned around backwards.
Fortunately...this is one of those things that can be seen as soon as the hood is raised. So those of you owning the 3.4L Vin "S" engines, it might be worth your while to take a quick glance, just to make sure that the S/S clamp screw is on the Left Side of your Throttle Body...and not the Right Side! As for the miserable performance of the stock, hybrid disc/drum brakes in the car, I have since done a complete LS1 brake conversion and the car now stops very nicely with four new, large steel platters!
Bob
The second time it happened many months later. But this time he was in heavy traffic and somehow, after his brakes faded and failed, he managed to run completely off the road, plowing up a row of bushes instead of cars and people, badly damaging his front bumper, hood, and the drive shaft cross member which I replaced.
Thankfully, neither he, nor anyone else was harmed. But this time though, I did a better job of investigating and finding the actual cause of the problem. It was such a simple thing, but it could have been disastrous. Here is what I discovered:
(1) Checked under the dash above the gas/brake and found no carpet/cables binding.
(2) Followed the dual cables from the firewall to the throttle body (no binding).
(3) Unbolted and removed the plastic shroud around the cable hook-ups on the TB and cycled the double spring mechanism time and again, I could find nothing wrong.
(4) Removed the throttle body and serviced it from top to bottom, with two new sensors installed.
(5) Upon re-installation of the TB and cables, I was slipping the air handler hose around the inlet of the TB when I spied what actually went wrong...
(6) Whoever had last serviced the unit prior to the Camaro changing hands had REVERSED THE STAINLESS STEEL CLAMP on the air tube from being positioned outboard (left side of TB when facing the engine) and opposite from the area of the double spring actuated, dual cable bell crank on the right side of the TB, facing the engine!
(7) When improperly reversed, the hex-head of the S/S clamp is moved into a position that allows a right angle piece of the bell-crank mechanism to move up over the hex-head and get stuck on top of the bolt head. So whenever the gas pedal is pressed nearly to the floor, even with the strong dual springs working properly while trying to return the throttle to the neutral/idle position, it simply stays at the WOT position. When this happens, the cables go completely slack and the S/S clamp screw holds the throttle in a WOT position until physically jarred loose or pulled free by hand.
(When this occurs under normal driving conditions, nothing short of turning off the ignition key (if even possible) can be done to stop a 'Runaway" condition from happening.)
Whoever had serviced the car must have completely removed the clamp which is normally held in place with the hex-bolt on the left side by a pointed rubber rivet poking through a small hole in the bottom of the S/S band. Some Yo-Yo had actually slid the entire clamp off of the air tube ...and put it on backasswards with the rubber rivet stuck back through the hole in the bottom of the S/S band! The oval top hole in the clamp where the air pipe fits in gives no indication if it is turned around backwards.
Fortunately...this is one of those things that can be seen as soon as the hood is raised. So those of you owning the 3.4L Vin "S" engines, it might be worth your while to take a quick glance, just to make sure that the S/S clamp screw is on the Left Side of your Throttle Body...and not the Right Side! As for the miserable performance of the stock, hybrid disc/drum brakes in the car, I have since done a complete LS1 brake conversion and the car now stops very nicely with four new, large steel platters!
Bob
Attached Files
luckily I had the sense to throw it into neutral and shut it off.
), but that shows the fact that many drivers may never even go WOT and therefore never experience the problem if the risk is there.
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