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High revving downhill (A629) Ainley Top to Halifax

Posted: Fri Aug 02, 2024 11:31 am
by simonc
Hi fellas. Yes, I'm probably flapping like a wet hen, but there's a particular road I travel on pretty frequently on the way back into Halifax from Leeds after getting off the M62, which is causing some grief. I must admit it's a pretty steep gradient (I have looked but cannot seem to find out what it is) and it has two speed cameras along it to enforce its posted 50mph limit.
So what's getting me all-a-dither is that even though I'm sticking to the speed limit when I'm going down the hill, it seems through my engine is revving big-time, keeping the automatic box in a low gear, seemingly incapable of letting the car 'run' a bit freer down the hill letting me control the speed on the brakes.
(It's taken quite a few goes to write that sentence and hope it make sense).
Is this normal in an auto-box car? Does it decide to keep it in low gear or is there a technique I'm missing to enable the box to 'run' thus eliminate the high revs, letting me slow the car on its brakes?
Your thoughts would be much appreciated. Ta.

High revving downhill (A629) Ainley Top to Halifax

Posted: Fri Aug 02, 2024 5:47 pm
by Scott560
I have no idea about old boxes, but newer gearboxes do have inclination sensors. The wifes 2017 civic does this and it's by far the most useful thing the CVT gearbox does. It will hold a lower ratio when you encounter an incline, but tends not to do it so much down hill (as the car has 0 engine braking anyway).

Another 4th gen auto owner should be able to comment more helpfully.

Are you in sport mode at all? Using cruise control?

High revving downhill (A629) Ainley Top to Halifax

Posted: Fri Aug 02, 2024 8:05 pm
by simonc
Hi Scott and thanks. To answer, I'm not in sport mode and my car doesn't have the cruise function.

High revving downhill (A629) Ainley Top to Halifax

Posted: Sat Aug 03, 2024 10:13 am
by wurlycorner
4th gens don't have any inclinometers or anything like that. They're a very basic autobox (compared to modern times).
Generally it's a good thing to have engine braking (keeping it in a low gear) rather than running on the brakes, so tbh it sounds like the box/engine combo is well matched?

I haven't ever studied the autobox section of the service manual, but I expect there might be some description and maybe even some graphs showing how the box should behave depending on speed/engine rpm.

High revving downhill (A629) Ainley Top to Halifax

Posted: Mon Aug 05, 2024 8:33 am
by simonc
Morning, Iain and thanks for that.