My Lightning Lunges foward aswell. all it means it is ready to go

 

...seems a lot of the Lightnings do this (mine included). Since all of them are 4R100s, maybe it's just related to THAT tranny. Mine only does it after it sits overnight or for a few days. I think it's just the drained-back fluid whipping around in the trans; it's a big sucker!

 

Just for your info, I had a 97, 99, and now 2000 that all did that. It's most noticable in my garage since I have "stuff" all aroud it and park close to the stuff.

When you start it it "edges" forward maybe an inch or less. I put my foot on the brake to prevent this.

I don't consider it a problem at all. I believe everyones does it to some degree but it just goes un-noticed.

Bob

 

I wonder what is causing this. Mine just started doing it last week. It's an '01 with the 4R100. The best way I can discribe it is the feeling you get if you were in a manual car at idle and pop the clutch to only have the vehicle go nowhere and stall but it doesn't stall. I say it's a pretty big jerking motion but like others, it doesn't happen all the time, only sometimes after it's been sitting for atleast 6 hours. I think I need to file something with the NHTSA.

- Dae

 

I went ahead and filed with the NHTSA. If you choose to do the same, make sure you have your VIN number. My complaint number is 10008507, but I'm not sure if anyone can do a search with it.

- Dae

 

I don't see it as a problem. It rocks, not rolls. (I didn't plan that, it just came out that way. )

 

Familyride,

Your right, it's not really a problem but still a problem. The reason I say it's still a problem is because of a few things. One is that I don't know if it may cause and long term damage. 2, If I got to sell it and someone starts it and he jumps, they're going to be asking what might be wrong with it. And 3rd, if for whatever reason a child is in front of the vehicle (sitting or leaning on the bumper) and I or anyone chooses to start the vehicle to just listen to the radio, and it jumps, it could knock a child or even an adult to the ground.

- Dae

 

Could this also happen when in gear? Sometimes my '01 EB does this at stop lights and at other times when I come to a stop and leave my foot on the brake. The first time it happened I was in a drive thru, I thought the guy behind me rear ended me. A yelling match ensued...

 

What we're talking about is when it's started after sitting and primarily in the cold weather. Speculation is the ATF in the TC as it spins up at first and the ATF is cold.

You'll notice it more if you crank it up in confined quarters like in a garage where you're close to other things so it is more noticable.

 

Ya, I know... I was wondering if anyone else had experienced the "lurching" effect after normal driving and if the two MIGHT be related. After start-up in your driveway is one thing, but when this happens in traffic it's more than a little disconcerting. It happens to me a couple times a week regardless of outside temp. I asked the dealer to look into it and all they did was inspect my brakes.

 

My Expedition sits outside in the driveway all winter. It has NEVER done anything remotely resembling what you people are talking about. And it has been quite cold in Northern Virginia this winter.

 

Since this post first started, I've noticed mine does a jig, but it seems to be more of an engine torque related issue pushing the vehicle sideways rather than forward. I'm sure my Expy has always done it, but just hadn't paid too close attention.

Bridge, does you idle speed increase when you feel the "lurch?" These engines are notorious for having an idle problem. Common fixes include a new IAC valve, clean MAF, check TPS, etc.

 

jimmsimm,
It does for a second...Although I can't say how much. When it happens the engine revs and the car jumps forward a foot or so. It's sudden and unexpected so I haven't had a chance to look at the RPMs when it happens. I'll look into the fixes you suggested, thanks for the ideas.

 

I cannot believe that your truck "jumps forward a foot or so" if it is in park with your foot on the brake.

 

Blue,
My first post to this thread (see above) asked about a similar problem while in traffic; for example coming to a stop at a light, in gear with foot on brake. My problem does not happen in park, so I think that Jim was suggesting an idle problem which I guess could over-power a light brake pedal.