Silly_me

I was driving home yesterday, approaching my favorite 90 degree right hand turn that leads to the bypass that will take me home, I make the turn with a brisk pace and a little left foot brake, the tires protest but the corner is made in proper style as I swung the four thousand pounds of my V8q deftly about.

The road straightened out and it was all acceleration now. I reach 50mph when I come up to traffic. I let go of the accelerator while my left foot covers the brake.....but the car kept going **eek**

I tapped the brake. Still going. I apply ? brake, but I'm fighting the engine still. I flip the cruise control switch on and off....NOTHING! I do it again, over extending the switch on the stalk. I slip my foot under the accelerator, but there is nothing hanging it up. I'm just about to switch to neutral and kill the engine when I tap on the gas. The unintended acceleration stops.

I can't get this scenario to repeat, but I wanted to know if anyone had any ideas as to what could have caused this? I'm thinking a fubar in the cruise control system, that is the only thing that makes sense. Before the incident, before I entered the surface streets home I spent my typical 50+ miles on the highway with the CC set on at my typical 80mph..... Thoughts? TIA

Quattrotrac

Take a look at the cruise control linkage under the hood. Chances are the holder bushing has worn out, the rod slipped out of place and is sitting on the throttle keeping it open. Playing with the accelerator pedal like you did, may have cause the rod to retract, towards the firewall, allowing for the throttle to come back down or just shifted it out of place.

The only other thing that comes to mind is a seizing throttle cable. Both are common issues on the V8, but I think the latter is probably what you'll find to be the problem. Either fix the linkage or dump the rod (no CC).

boxerfan

If you follow the throttle cable to the back of the motor near the firewall you will see the rod that connects it to the TB. Here's the goofy part... follow that rod to the FRONT of the motor. This is where it gets exposed to the elements and starts to bind up. If you reach in with your finger you can move the throttle rod. Pull it fully open and then let it close slowly. Once it has returned to what should be the stop position test that by pushing on it a little. You will probably find that it has not returned to the stop and has not activated the idle switch. This was your erroneous cruise condition.

So, now you know what and where. How to correct it. Just squirt some lube at the front and rear of the rod? Nope. The linkage is getting hung up behind the TB at the front of the motor. You need to remove a few things to get at the mechanism. You might want a can of compressed air to keep everything clean. Then you can lube it. You might as well take the air plenum cover off and lube the rear stuff as well. Then, while you have them exposed, check out the fuel lines that run back and forth between the fuel rails at the rear of the intake manifold. They tend to start leaking. HTH.

boxerfan

I just tried this the other day and it worked great. I totally forgot you were having this issue until just now.

I wonder if the throttle cables have been OK all along? Perhaps they do start to have more friction over so many years and the added speed of return allows the TB to close properly. If you flick the throttle at the front of the block it will return to idle position. Do it slowly and it won't. Either way, give the lube a chance first prior to doing the throttle cable.

SteveAngry

I'd look at the throttle rod assembly or make sure your carpet isn't jammed under the gas pedal.