My Disco has parked for 3 months or so while I try regain the motiviation to work on it..

When it was parked it ran tip top (apart from driveline vibe). I took it for a spin around the block maybe a month ago, all good.

Yesterday the battery finally died. Wouldn't fire. So I boosted it and she fired up. Now the thing likes to drive itself. It's currently on jackstands and as soon as I put it in Drive it accelerated itself upto 60km.

Also if I rev it in neutral it will come back down then rev to 2000rpm'ish for 5 or so seconds before returning to a normal idle.

Absolutely nothing has changed other than the battery dying. Anyone ever heard of this?

 

Could be a sticky throttle or bad TPS. I'd check the linkage real well and then use a scanner like the UltraGauge than can read live TPS data. If you let off the gas but the TPS still reads 20%, well there you go.

 

And the same scanner/ultra gauge could look at other sensors, like coolant temp, to see if they are way off, like -40F for a bad coolant temp, which dumps fmore fuel to compensate. And of course cleaning the IACV, which controls idle air and thus idle rpm.

 

I am going to say your ECU lost its memory on the adaptive engine controls.
How long was the battery dead for do you know?
While it should not have lost its memory, it can happen.

 

It lost its load or its mind.

 

This makes the most sense.. While it is possible it is TPS related or some of the other suggestions, this truck has always run tops. While definititely possible, it'd be a bit odd to be parked running, then problems a month later.

What does this mean as far as resolution goes? Dealer only re-programming or something I can do myself?

I'd venture to guess to was dead for maybe 2-3 weeks. I'm not entirely sure though.

 

It will adapt as you drive for a number days, (perhaps not safe) or crank and let run in place each day. This simulates a "drive cycle". But I still believe that you exceed the default performance, so taking the IACV off and cleaning it is a cheap way to speed this process along. Can't hurt anything.

 

Perfect thanks mate. I've heard of cars losing their adapted fuel trims etc when the battery is left dead for a period of time, never heard of one losing its memory to the point of driving itself though. Sounds pretty unsafe.

All over discoweb guys swear that yanking the battery terminal can NOT reset the adaptive learning.. I guess like everything so far, my truck is an exception to the rule.

 

There was a guy on here a while ago who left his truck sit for over a year with no battery, when he installed a new battery, truck was fine when parked, his alarm went off.
The ECU and alarm had lost their sync, he had to have it towed to the dealer to have them matched back up.

 

Is there much involved in removing and cleaning the IACV? Is it the little square piece with the 4 small torx head fasteners?