If I leave my truck parked for a few days without running it, or if I just start it to move it out of the garage and later again to bring it back in...without driving it...and do this a few times...it will sometimes run rough. It's almost as though it's dropping a cylinder...but not that strong of a miss. All I have to do is drive it for half a block, and it smoothes-out and runs perfectly. Also, if I let it idle for more than five minutes, it will smooth-out. Of course it doesn't do this every time it's parked for days...just sometimes. I'm wondering if there's some unburned vapors in the cats that's sending a false signal to the computer?

Whadda you think?

BTW...It's got almost 36K miles on it.

Thanks.

 

I own a 2002 Screw, a 99 Miata and a 90 Linclon and they all do that. I think the sensors like the ones in the exhaust have to get good and hot to work right. I'd like to know otherwise though.

BE

 

Pretty much all injected cars will behave that way, if run only a few mins, and then shut down without being allowed to warm up. My guess is the injectors load up with raw fuel, which takes a bit of running to clear. Everything, multiple brands of cars and trucks, I have owned that are injected act exactly that way.

 

My guess is that the gas went "bad" and gets mixed up when you move. I thought my trucks engine was going bad when I picked it up. The dealer left me with about 1/4 tank. That 1/4 tank probably sat in there since the guy traded it in until I picked it up. It ran smooth when I drove it normally, but it ran really rough when I put the pedal through the floor boards.

I haven't noticed anything since, except that the SES light came on (getting fixed as I type). I'm hoping that they don't say the intake I put on set the code, I put it on AFTER the SES light came on!

 

Thanks guys. It's good to know that I'm not alone and that there probably isn't anything to worry about.

 

a number of things happen to cause the rough running.

for the first approx 5 min of a cold engine running the primary by-product of gassoline combustion is water! so when you start the truck for less than 5 min a huge amount of water soaks your o2 sensors and your temp sensor has not come on line yet. then you start it later and a ton more water is produced so the computer is doing everything it can to keep the engine running until the water is cleared. (there is also a small amount of water in the cylinders)

That is why there are weep holes in mufflers so that if you don't run the engine long enough the water has a way to drain out. It is also another reason why short trips are so bad for your engine.