Periodic rev drop

Hi,

just came back from a ride and I noticed that the engine revs dropped periodically when waiting for traffic lights. The thing is that it only happens when the car is in D mode (I have an automatic gearbox in a Jimny from 1998). I can see the lights dimming a bit before the revs up again and the lights go brighter. This does happen every few seconds, but no discernible pattern could be found. Does someone know what the problem could be? I just had a total gearbox overhaul (which was quite costly) and wouldn't want that again...

Has it got A/C

Yup, it got A/C, but I am pretty sure it was off this afternoon.

@GeorgeC, hmmm, that is also an option

If it was on it would be that I have auto and also pop mine in to N if sitting at lights or for along time

So I checked today and the AC was definitely off.

It also feels a bit as if the car wants to jolt forward (as if the gear is engaging).

On an auto they will move forward when d is selected

I got the transmission overhauled about a month ago. I'll check the fluids today. Up until now only problems with my jimny transmission... Now the transfer case chain is slipping...

kirkynut wrote: Why not put it in Park. That's what you ought to be doing!

Kirkynut

Gives the driver behind a panic attack when you pass reverse as you stick it back into drive too.


The Renault Nissan is auto, I just leave it in D all the time and hold it on the handbrake*. If I was stationary for a while I'd turn the engine off.

*I always used to hold autos on the footbrake, but the Renault Nissan has steering so dodgy that holding the footbrake on when the discs are warm deposits a few microns of dust on the disc, and then the steering oscillates lock to lock under braking for evermore, until you buy new discs