Hi guys,

I've gotten a lot of info from this site and I think it's great. I have an interesting problem with my '01 Expy 5.4 that I need some advice about. About half a dozen times now (twice within the past week), I was sitting at a stop light after the truck is warmed up and the truck would surge forward. It's strange because the speedo jumps at the same time. It only lasts for a second then everything goes back to normal. Also because I have the speed volume set on the radio it gets louder too.

I'm assuming the tach and engine speed jump from the speedo jumping but I'm not sure. I've only got 3K left on my warranty so I need some advice before I call the dealer and they certify me nuts.

Any help would be appreciated!

Steve

 

"surge forward" Do you mean that the truck actually moves, ie: the wheels turn? If so, I would think it's a trans. problem--warranty--now! If the wheels don't turn, then I would think it was a computer problem. Do you have a chip? If so, reclean the contacts on the PCM--if not, warranty again.

Dan

 

Thanks for the comments LightninRod. To answer your questions, yes, the truck tries to move (I have to hold it with the brakes). No, the truck is all stock. When the speedo jumps the engine speed jumps too and the truck tries to move. Strange, huh?

Any additional comments are welcome

Steve

 

I've changed my mind after reading your second post and thinking about this.

Something is opening your throttle but I d/k what??? Or, the IAC is hanging up and varying the idle rpm--or the PCM is sending/sensing the wrong signal...........I think.

You've got 33,000 miles on it so the IAC could be dirty and/or worn but I haven't seen one that would cause the idle rpm to surge enough to overpower the brakes???? The dealer should be able to figure it out though.

Dan

 

Dan,

I also thought the IAC but why would the speedo jump? Do you think the speed sensor is linked to the IAC opening the throttle open part way if it thinks the truck is going 40MPH?

I'm going to make an appt. with the dealer to at least start the ball rolling. Maybe they will actually find something or if not I'll at least get the problem on record.

Thanks for your help.

Steve