Engine 'Flaring' between gear changes.Argggh.

[ernie989]

What you are concern with the rpm is call progressive shifting. keeps the rpm so the rpm match the rotation of the wheels. Not like the old autos where you ram the gears in shifting into higher gear. if you learn to use the progressive shifting you will have a smoother ride when shifting to higher gear.

[xiaogary]

I mean the nut is blocking the throttle plate from closing completely. So after he remove his leg from throttle clutch in, plate never close completely, some air manage to go in, so explaining the flaring.

I knew it becos I purposely did this with my 285 degree camshafts to make sure engine doesnt dies when I clutch in due to low vacuum (which is a problem with high cams). It makes the engine flares when clutch in.

[byron84]

Mine intermittently does a similar thing. When I press in the clutch, the engine revs don't fall as they should. I drove a Focus which did the same thing. When I drove the Versa, the responsiveness was excellent and the revs fell immediately when the clutch was pressed in.

I don't know why it does this, but it doesn't always do it. Sometimes it's worse than other times. It definitely feels like the clutch is wearing faster than it should, and I think this might be partly why. My Lancer did the same thing and the clutch also seemed to wear faster than other cars.

I don't see any advantage to having the engine rev longer after you press the clutch in. When you shift into the next gear up, the revs will be lower, not higher... so it doesn't make any sense at all to keep the revs higher after clutch pressed in.

[Unidentifiable]

I mean the nut is blocking the throttle plate from closing completely. So after he remove his leg from throttle clutch in, plate never close completely, some air manage to go in, so explaining the flaring.

I knew it becos I purposely did this with my 285 degree camshafts to make sure engine doesnt dies when I clutch in due to low vacuum (which is a problem with high cams). It makes the engine flares when clutch in.

On EFI engines, the throttle plate does NOT control the idle of the engine. It's controlled by the IACV. Unless you max out the IACV, the throttle plate will not control anything. If you close that plate completely, it can damage both the plate and the throttle body. That screw is not there to adjust the engine's idle, (this can only be done electronically, that I know of), it's there to maintain a degree of adjust-ability while components are assembled to keep manufacturing costs lower (precision manufacturing is more expensive, and would reflect in the cost of the vehicle/replacement parts).

Your surging problem (OP) is more than likely a slow IACV or a slow throttle stepper motor. If you don't have decent mileage built up, the issue will likely cure with time. If you're over 10,000 miles by now, I'd probably check further into it.

There is never a call to replace sensors randomly - this is what service garages do - they throw your money at the problem until it's fixed. Proper diagnosis of automotive malfunction went out the window with the advent of OBD systems. Get yourself a multi-meter and the specifications to test the sensors, and be a real mechanic.