I just replaced all 4 O2 sensors today (which wasn't much fun), and when I started the truck ('99 Discovery Series I), it revs right up to over 3000 RMPs! It won't kick down, so I let it run for a couple minutes, and it still was running at over 3000. I tried that two different times. What is the deal!?!?

I bought the O2 sensors from Atlantic British, and the guy told me that since my truck is a '99, that it "definitely" has AEL (I think that's what it's called). There were two kinds of O2 sensors: for trucks with AEL, and for trucks without AEL. Could THAT possibly have anything to do with it? I'm afraid to put the thing in gear!

Thanks!

P.S. The Check Engine light is still on, but I assume that's b/c the computer hasn't yet adjusted to the new sensors.

 

The new 02's have nothing to do with your idle. Either your throttle cable is stuck, you have a really dirty t/body or your IAC, idle control valve, is carboned up or has failed.
Do not drive it that way and don't think letting it idle will make it go away.

 

A vanced
E vaporitve
L oss

You have a vacuum leak or a stuck throttle cable.
Make sure that you didnt remove any vacuum lines and mess with anything else.
And no, the CEL will NOT go off on its own, you must use a OBDII scanner to reset the light.

 

Mike is right....check the throttle cable. It's probably stuck on something. Happens to me all the time when I work on the intake and makes the truck rev about 3-4k rpm. Look near the intake and I'll bet it's stuck on a bracket or something.

 

Thanks guys! This has never happened before, so I HAVE to believe it's something *I* did. Where is the throttle cable located?

 

It is on the throttle body, it is the only cable on the engine.

 

Yep! That was it: popped the hood and could immediately tell I knocked the cable out of the housing. Runs fine now. Thank you all for your help!