hey guys, i think ive read this around here before so sorry if its repetitive, when i start my car up it idles at about 1500, but after i ride for a bit and put it back in park it idles around 700-800, is this a cat problem? thanks for all help in advance.

 

How long does it stay at 1500k

 

i havent really waited to find out, about 5-10 minutes i think, its about a 10 minute drive to school in a 55 mph zone and by the time i get to school its back down, if that helps any lol, but it just started, or at least i just noticed yesterday and its continued to do it today

 

My car does this too. I think its to warm it up quicker. In cold weather it stays at higher revs longer.

 

i heard it could be because of the cat being clogged, because this is the first time its dont it all winter

 

When you start it is the engine cold? If it is, its supposed to idle at about 1500 until the car warms up a bit.

 

yeah the engine is cold

so this is normal then? nothing to worry about with the cat and stuff? i have been having some rough shifts too and trans fluid is fine but i have heard that clogged cats can effect the engine power output and shifting sometimes, so i just thought i would check in on it

 

I would assume it to be normal myself. But mine usually drops to 1K in like a minute of idle

 

When you first start it, and the engine is cold, it is normal for it to idle high. My 3.5L idles at about 1,300 RPM for the first min or so, then it comes down to about 1,000 for another min, and then right around the time the temp gauge starts to register on the dash, the RPM's fall to the normal 600 RPM Idle. (that is normal for my car with the 3.5L)

My mom's Bonneville when first started (cold) will idle at 1,500 RPM for the first min or so, then drops to 1,200 for about another min, then seems to idle around 900 RPM until the car is FULLY warmed up, and then drops to the normal 700 RPM idle.

So based on what I just said for "normal" cold idle times, I guess you can be the best judge of whether or not yours is normal. 10 min at 1,500 RPM does not seem normal, but if it seems to drop a little, and then a little more, kinda like I explianed, then I would say you are fine, and it is normal.

 

If you think you cat it plugged. Drive the car and get it nice and warm. then look under the car when its dark out. If you cat is glowing red, then it is plugged. Also, a plugged cat will cause you to have a lot less power, due to the exhaust restriction.