Loosing Power

[elkyss81]

I need some advise... I have a 99 doolie with a 6 spd, only mods are a k&n filter and the guy I bought it from says it has a chip (never seen it but it does blow some black smoke when i get on it). I am getting a terrible hissing on fast idle, or when im feathering the throttle at hwy speed. I have taken the belt off and run it and it still makes the noise. However, it only does it when it is about 45 degrees or cooler outside! i pulling my hair out!

That's your exhaust back pressure valve working. It's supposed to do that.

 

[DaveBen]

I would get rid of the K&N filter. It does not filter very well. Many other filter kits are available that work. You will trash your turbo with the K&N. Others will comment on the hissing, I don't know about the '99 models.

Dave

 

[BIG JOE]

That's your exhaust back pressure valve working. It's supposed to do that.

X2.

It'l do that 'til the Oil, Block, Heads and Coolant sensors tell the PCM.. We're "Good To Go", Temp wize. Best thing to do is.. let it warm up some.. before you drive off.