Auto Box, Is This Normal?

[mike99]

I thought recently that the auto box in my car was slipping, in second gear it revs but the engine and gearbox don't seem to lock up also it does it in third sometimes. It does drive ok and pulls ok. If while its doing this i push it into tiptronic it bites the gear and goes fine, I thought maybe it does this in auto for a smoother ride???

[Guest MATT jr]

mmmmmmmmmmm, if it is slipping, its gonna cost you (

[mike99]

mmmmmmmmmmm, if it is slipping, its gonna cost you (

[Scorpiorefugee]

Maybe a glimmer of hope or perhaps a waste of time but, these are very similar symptoms caused by MAF problems on the old Scorpios and, I believe, other makes as well - even BMWs.

 

On the Scorpio at least, disconnecting the MAF would often cure the symptoms.

 

Faced with a

[MrT]

I recently bought a duff new MAF and when it went out of spec (fault = implausible reading) it somehow locked up the autobox in 4th(after knocking into 4th from 5th at speed) and giving an autobox out of torque specifications alarm. The box would not work again properly until I reset the fault code with VAG-COM. I also got an EPS alarm at the same time, again due to the MAF. Not sure how the MAF did this, but it was repeatable.

[Guest MATT jr]

when our maf kicked the bucket, it did make it seem that more rev was required to "go".

 

but mike said it drive ok and pulls ok, so would this discount the maf?

 

MJR

[Scorpiorefugee]

My old Scorpio used to do all sorts of strange things but the symptoms were mainly associated with an inability to hold any gear without slipping, especially after a few miles. It didn't have any means of manually controlling the gears but I would imagine that the tiptronic (I once drove a BMW version) overides the bulk of the 'Auto' control system which is now electronic and uses lots of sensor feedback to control gears etc. The MAF provides a useful indication of the load and driving style and if this is out of range it is not inconceivable that the control system gets confused and becomes incapable of making sensible decisions.

 

I found that disconnecting the MAF gave very positive and reliable changes when leaving it connected made it virtually impossible to drive without a great deal of slipping drive.

 

Sadly, I was too stubborn to accept that the MAF was causing this and eventually blew the head gasket because of over revving before I got around to replacing the damned thing. It is, however, a well documented standard fault.

 

I hope your Gal does not meet the same fate as my Scorpio.

 

Ron.

[mike99]

Thanks for the help with this, I have just come back from the scottish highlands after a week and 1400 miles. The car has coped fine the whole time but still slips(i think) in 2 & 3. I will try disconnecting the maf, but not sure if theres anything wrong as I've averaged 40 mpg on the journey. I remember reading somewhere about disconnecting the battery too, not sure where though but I might give that a try also.

[Dave-G]

I have today tried swapping my MAF with a friends auto galaxy - I still get my occasional gear slip' too.

 

I notice EVERY time it occurs - the engine temperature is between 85 and 90 degrees :lol:

 

Would this be the case with yours mike?

 

It performs faultlessly above and below this temp.

 

Bear with me here because I have no scientic facts to explain the following apart from it being temp related, and something I discovered in a previous trial and error post. (part of the t-map sensing is engine temp)

 

I found that trying the car with the t-map sensor unplugged causes gears to change with a pronounced slam, rather than the gentle, progressive and subtle change.

 

Mine currently slips a bit then thumps into the required gear. Given that this occurs at the stated engine temperature range. Does anyone know if there is a route to the gear selection/requirement depending on engine temperature? I have also swapped my new t-map sensor with my frien to rule that out.

[mike99]

Mine doesn't seem to be any different at different temperatures. but like yours it seems to slip them snatch into gear.

If I put it into tiptronic mode it snatches into gear straight away, making me think its something else. I really haven't had time to try anything yet though like disconnecting maf or battery.

 

If I put it in tip mode then drive hard, 4000rpm in first, change to second then same again into third it bites the gear straight away without slipping, I would have thought this would be the time when its most likely to slip. I find it slips mostly below 2500 rpm and It seems to do it all the time in second and most of the time in third.

[lazyb5]

Hi guys

my gal does the same had it for about a year

i find i can keep the revs about 2.5 to 3 thou and it slips through the first 2 gears and bites on the 3rd.

If i boot it ,it catches 1st,2nd and 3rd without slip and it takes off like a scalded cat

Since i`m getting 40mpg out of it on a run and 30-35 around town i havnt bothered with it.

[Dave-G]

Auto box specialist had the side off it today. As they suspected (they spoke very knowledgeably about the box) a piston had started to crack around a welded head, allowing fluid to leak past.

 

They had shown me one off a landy (jatco box is also used on rover 75's and jags apparently) that looked a bit like a can with teeth around its edge. It was maybe 5" wide and nearly 3" deep.

 

They now have to remove the box -