Edward

OK, depends on the engine temp, but I swear it is not my imagination. At a stoplight, in neutral, I look at the tach. Clutch in to engage first, and some of the time (yes the engine is warmed up) the RPMs climb ...just a hair, I mean minute, but noticible. Can't figure it out. What gives?

Edward

Auto_Werks 3.6

If it is near the beginning of your drive, the thick gear oil in the transmission could still be warming up, even though the engine is at temperature. When you depress the clutch and the tranny stops it takes some of the load off the engine. Thats the same reason why some people insist on starting the engine with the clutch depressed even though there is no interlock on our cars. I'm not surprised by your finding, and I certainly wouldnt be worried about it.

Edward

Naw, it is not at the beginning of my drive. I know that the car has to be "very" warm ...especially since the WUR has everything to do with idle speed. But for the life of me, I can't figure out why there seems to be this odd correlation of clutch in=slight bump in idle speed. And not even "every" time at that. The car drives better now than it has ever before, now with a fresh clutch, plugs, oil in engine and tranny. So no complaints ...just really odd and I can't figure it out

Edward

Peter Zimmermann

Edward: The last thing that I want to be is negative, but I think that we should consider that major work has just been done. Let's think about what happens when you depress the clutch pedal; (1) the clutch arm moves forward, and pulls on the cable, (2) the cable moves inside the tunnel, (3) the cable pulls tight inside the bowden tube, and (4) the cable interacts with the assortment of arms and springs under the differential housing. That means:
1. The cable can somehow be interfering with the throttle connection at the pedal cluster(this is unlikely unless you also had a new cable installed).
2. No interference possible...
3. The possibility exists that the bowden tube is not located correctly, or is adjusted wrong to compensate for the cable not being set up correctly. In this case the bowden tube might be touching the throttle lever (bell crank) on the side of the transmission, moving it just enough to change your rpm. Visually check your bowden tube and make sure that it is routed over the throttle lever, and is not touching it.
4. No interference possible...

In addition, if something was left loose during R&I, when the clutch cable pulls on the release mechanism it's possible that the throttle linkage at the throttle body is changing position slightly due to the engine moving in the chassis - highly unlikely.

Mike Murphy

I think what you are describing is normal. If you're talking about just a "hair," then I think it's normal. What's happening is that when you are neutral, all the gears in your transmission are spinning. When you push in the clutch, all the gears in the transmission are stopped. So, basically - it's takes horsepower to run all those gears - and circulate that oil - even if you are not going anywhere.

I have seen this with other cars.

Edward

Thanks, guys. OK Pete, will check out the tube/linkage at the bell crank this weekend. All feels tight, vibration free, and smooth, so I'm sure the engine is in there snug. As always, I appreciate your expertise and the specifics!!

Edward