Autobox - Jerky change 4 to 5

[andydckent]

Hello,

There are a few threads on this already but thought would post also.

Basically the shifts between 4 and 5 are jerky (also noticed once between 2 and 3). This seems to occur when I'm using a bit more power but in particular when the car shifts down into 4 having been cruising in 5. It's not the down shift but when it tries to shift back up it jerks a few times before it manages. The car has obviously been off the road for a couple of months and the ecu will have reset. Just wonder if this is normal and how long it might last as I have never experienced such behavior on previous resets?

I have checked to atf level and happy to report that it is full and red.

Should I also consider resetting the ecu again as I guess it's first real run would have been for MOT check?

Thanks

Andy

[Ghost_2008]

It will settle down as it learns the biting points/shift patterns and it can take a while... However I understand that mismatched ecu's, as in engine and gearbox ecu's Can cause some minor issues...

I reset my gearbox recently and I had similar behaviour but it's much better after a few miles....

[bungle]

Ive had/am having this issue myself. Doesnt seem quite as severe as youve described it though but it does jolt quite badly into 5th gear between 40 and 75ish mph. The issue has reocurred due to having an ecu reset after atf fluid replacement last week. A good way Ive found to combat it is to lift your foot off the gas as you push the gear stick up then straight back on the gas as smoothly as you can. After doing this for a while I found I eventually I didnt need to bother and the gear change was smooth through all gears with my foot down.

[Davezj]

i am with the guys above, after a battery disconnect the auto box gear shifts will probably be jerky from 2-3 and 4-5.
it will settle down, but some gear boxes take longer than others, anywhere between 50 and 300 miles in my experience of driving the 3 autobox i have had it does vary quite a bit.

[Nick Mann]

Also, no offence intended if you already know, but did you check the fluid level after a short drive with the engine running on level ground and the gearbox in neutral?

[andydckent]

Was checked after drive on flat ground but without engine running or gearbox in neutral. Didn't realise this was a requirement. Will check again.

Andy

[Davezj]

This is how I always check it.

Level ground

Engine running,
hot ATF,
cycle through gears (P R N D 1 2 1 D N R N D 1 2 1 D N) ,
check the fluid level on HOT part of dip stick.

Remember lots of auto box dip sticks are damaged and broken on the plastic collar, there is a 'V' groove in the plastic collar which lines up with the pin on the side of the dip stick tube this guberns how far the dip stick goes into the tube . If you dip stick plastic collar is damaged you might not have the 'V' groove in the plastic collar and you might be pushing the dip stick to far into the tube and getting a false high reading on the level.

[andydckent]

OK so it seems that this problem was in fact fuel cut. For some inexplicable reason the mechanical boost controller seems to have become stuck closed. When I removed it the problem was gone. I took it apart and cleaned it and the ball seemed to be stuck at the top. Reassembled and refitted and it worked again without any problems boosting to 0.8 bar. However, this morning the problem is back so either the ball is stuck again or the colder air is causing the problem, I'm not sure, I suspect the first one as I actually slightly decreased the setting on the controller.

It's a Dawes Devices one. Has anyone else experienced the same?

[Nick Mann]

Cold days highlight fuel cut. Colder air = denser air = higher air flow.