Automatic Gearbox Operation 2.5KV6
 

Hi everyone, I need some advice on the operation of my Auto box;

When the car is idling, selecting Drive, or particularly noticeably when selecting Reverse, the car immediately starts moving. It's as though I have the engine idling too fast (but don't)

To keep the car from moving off I have to have a firm brake pedal press and / or the handbrake applied at it's fullest extent.

Otherwise gearchanges are normal when driving the car.

For background info:

Engine idling speed is measured at 775rpm.

The gearbox fluid has all been replaced with no change in the above issue.
I have replaced the entire (8L) contents and re-set the level via the level plug (5mm allen key bolt) under the gearbox using the methods and instructions found on this forum, plus reference to the Haynes and Rover manuals. Also we measured amounts out and back in and they matched very closely. I am 99.9% certain that fluid level is correct.

New Trans Fluid has the correct compatability.

I have replaced the lower gearbox mounting (a job that took hours due to one bolt clashing with exhaust sensor position !! - Not as easy as the manual or posts on the forum suggest) the original rubber was completely split.

Gearchange is now much less "notchy" when selecting Drive or Reverse, but certainly not silky smooth.

My Autel OBD2 reader communicates with the car fine, and there are no error codes present.

Is this a problem others have had ? I have not yet found reference to this issue in any other posts.

Thanks, Martin.

:beer2:

Hello Martin,

As your idle speed is correct I can't see this being anything other than the normal "creeping" condition for which a brake application is necessary.

If you feel that your handbrake requires excessive travel, adjustment is recommended.

Simon

Hi Simon,
It is not an issue with lack of brakes. I have adjusted handbrake twice now (new discs and pads were fitted all round a few weeks ago), but I have just rechecked the handbrake this afternoon and re-set once again per book instructions to be certain. No issues there.

I can also tell you that what I am experiencing is definitely not "normal" creeping. Car is pulling off strongly as soon as brakes are released (foot and / or handbrake) it feels rather like the gearbox would with an engine revving at 1000 to 1200 rpm, but engine is ticking over normally.

I have also just re-checked that the ATF fluid I used is 402N compatible and it is.

I'm presently reading various threads on reverse piston replacement and solenoid replacements. and wondering if those and the reverse clutch could be damaged / worn as Beinet1 experienced.

But I don't have much Auto Box experience so would anyone with specific Auto Transmission knowledge have ideas ?

When we dropped my wife's friend off after they had finished a shiift together she lived down a cul-de-sac, this was on the slightest decline as you entered the street. this obviously means it is an incline to reverse out.
So, the point being, select reverse in my 2.5 kv6 auto and the car would quite happily set off and reach around walking speed with no interaction with any of the pedals. Hope this helps

Hello Martin,

I don't blame you if you feel less than impressed with my last, admittedly rather basic, advice! :} By way of reassurance I have repaired three automatic gearboxes over the years. I fitted a replacement gear train unit and relined brake bands to our AP transmission fitted to the BMC/BL A series engine. This later needed an exchange torque converter which I also fitted.
I've also replaced a leaking converter-to-housing seal on my SD1 (which required dropping the gearbox) and the fluid pressure sensor and solenoid valves on my Citroën. So I can claim some experience on diagnosis and successful repair of automatic transmissions.

But Martin the description of your problem has baffled me! :D Could you confirm the engine speeds please in both neutral and after you've engaged drive and reverse with the brakes still applied of course. This will be most meaningful when the engine is at normal running temperature so that any fast idle setting is not present.

Many thanks.

Simon

i had this problem years ago . it was after my first self transmission fluid change. i slightly overfilled the box , even though i followed the manufacturers instructions. my error was that i did not use a spirit level to ensure a reasonable flat area to park the front wheels on. my roadside parking was on a gradient with quite a bit of camber , so this threw me out somewhat when setting the plug level. i now start from a flat even base with wedges under the front wheels accordingly to get a horizontal level. i must say that even though i did not add that much fluid over the required exact amount, the pull at normal tickover was barely stoppable with my foot firmly placed upon the brake pedal.all been fine ever since .. !!

OK, I have made progress, and will cover that in the next reply to xsport's post, but meantime engine speeds at idle using OBD2 reader were as follows:

All readings are fluctuating slightly according to my device, so these are approx figures, but not much difference between them.

750 to 760 rpm in P, R, N or D. Possibly slightly lower when in N than the other 3 positions, but a marginal difference - 10 rpm max.

As I moved the selector into each of those positions, the revs changed for a couple of seconds:
increased to 790 - 800 rpm for a couple of seconds in P, R or N, and then levelled back out at 750 - 760 rpm
When D was selected, revs dropped slightly to 725 - 735 rpm and then again, settled back up to 750 - 760 rpm.

I assume that is normal behaviour. All at normal engine running temperature.

Thanks for this advice Xsport. I too have a driveway with falls in a couple of directions, and though I thought we had set the car level, I re-checked it again today using a spirit level across and down the car length.
Worth doing, thanks.
Firstly I found the fluid was slightly under level, 0.2L approx. :duh:

Next we drained out 4L of the fluid we had put in the previous day (after approx 100Km of test driving) and it was now dark brown whereas it was a nice red colour going in (and we had changed all of the fluid not just half of it, so the colour was a bit of a surprise).

I decided to re-drain and fill again but could not get the same fluid this time, and have ended up using Nulon Full Synthetic SYNATF-4. (Nulon state it replaces the N402 and I believe other people have used it successfully. We have not got the same choices of ATF here in Australia that you have in the UK or Europe, so Ravenol etc are very hard to come by and very expensive)
Nulon SYNATF-4 is the same red colour but nice and clean ;)
This time I'm 100% certain level is correct and fluid temperature was 39 degrees when checking the level.:D

I also checked all of the solenoid and sensor resistances through the plug pins, in case I had a fault in there. To my surprise all of them gave readings within spec (other than the Lock Up solenoid which read at 13.4 Ohms when spec says max 13.2 Ohms and I think I'll live with that one at present), so unless any solenoids are sticking, they seem electrically to be Ok.

But I DID find that there was water inside the electrical connector when I twisted it open. That may have been causing some gremlins ? I have dried out thoroughly now.

So - results.
An improvement in the "running away" situation on tickover. Not what I'd call perfect but better.
Selecting the forward gears and P or N going up / down, all changes seem to be smooth.
But Reverse gear selection is now quite clonky, worse than it was when I bought the car, unfortunately - and I have installed the new bottom engine tie since. This will need more investigation / work.

On the short test drive it seemed to perform well - possibly slightly cleaner gear changes in both normal and sport modes, but only a few Km's covered so I need to let it bed in and see how it performs over some days, and if the reverse selection improves.

Thanks again.

Costs nothing to try the potentiometer as this cured a similar problem for John Aston who attends our Nano meets

put the ignition on II

without starting the car press the accelerator 10 times to the floor

1.8 engines only.
 

Hi Rob,

According to RAVE, that technique applies only to the MEMS engine management on 1.8 litre cars. It's performed five times within a ten second period, then waiting twenty seconds before switching off the ignition for a further twenty seconds.

The Siemens engine management fitted to Martin's KV6 doesn't need the closed position of the throttle position sensor to be set.

Simon :}