Im looking for help. I bought an 04 Dodge Dakota Sport, 5-speed manual about 8 months ago, had it checked out by mechanics and they said it was OK. However, when I start sometimes the engine noises will be very loud, almost as if it is over-reving, but the RPMs are normal. The one thing I have noticed is that the RPMs will increase by about 2-300 after I have taken my foot off of the gas and completely depressed the clutch. Is this something to be concerned about?
You sound like you’re talking about the fan clutch. It will produce a “whooshing” like noise at start up. Nothing to worry about there.
I’m unsure of the blip at idle speed changes. It’s possible the IAC (idle air controller) is gummed up and over shooting its set point It would also tend to do it in the other direction too, but not always. Clean the throttle body and, while running, squirt some cleaner in the air bypass port (this is what is controlled to set your idle). Don’t stall the engine, just squirt (stumble-recover) squirt (stumble-recover) squirt (stumble-recover). It may produce a miss fire code, but just unhook the battery for a bit. If that improves it (if this is indeed the problem) but doesn’t cure it completely, a disassembling of the unit may be required. It’s pretty simple, but may have ancillary complications with getting to the task. They like to make nothing simple.
I didn’t state it originally but the two issues are connected. The RPMs will only increase by 2-300 when the truck is making the loud noises (which then makes the noises louder). After the noise has stopped, the shifting will become normal again.