[dogtanion]

Hi

My 2008 335i changes gears cleanly and quickly until i change from 4th to 5th on WOT in Manual mode (sport).

4th to 5th on WOT causes a lag with some revving and then a lurch as the gear engages. I have had it throw a transmission error on one occasion:

4F8A0 Gear Ratio Monitoring Shift 4->5
Unknown error
Fault would not trigger MIL
Fault present and saved
Checksum Error.

The engine warning on the dash clears after the car is switched off and on (this has happened several times but only once have I had the error code above).

This is read from XHP (but the poor change up was happening prior to tune from 4th to 5th). XHP is Stage 2. Car is running MHD Stage 1+.

Any ideas of whether this would be fixed by new soleniods/transmission oil or whether it's more serious?

1st to 2nd, 2nd to 3rd and 3rd to 4th are all fast and instantaneous. Down shifts are also fine.

The other weird one is that sometimes putting my foot down in 5th in Manual at fairly low revs causes the car to still show Manual 5, but it's switched to automatic and I have to move the gear lever across to drive and back again to take control.

Thanks

Karl.

[Hawaiian340i]

Originally Posted by dogtanion

Hi

My 2008 335i changes gears cleanly and quickly until i change from 4th to 5th on WOT in Manual mode (sport).

4th to 5th on WOT causes a lag with some revving and then a lurch as the gear engages. I have had it throw a transmission error on one occasion:

4F8A0 Gear Ratio Monitoring Shift 4->5
Unknown error
Fault would not trigger MIL
Fault present and saved
Checksum Error.

The engine warning on the dash clears after the car is switched off and on (this has happened several times but only once have I had the error code above).

This is read from XHP (but the poor change up was happening prior to tune from 4th to 5th). XHP is Stage 2. Car is running MHD Stage 1+.

Any ideas of whether this would be fixed by new soleniods/transmission oil or whether it's more serious?

1st to 2nd, 2nd to 3rd and 3rd to 4th are all fast and instantaneous. Down shifts are also fine.

The other weird one is that sometimes putting my foot down in 5th in Manual at fairly low revs causes the car to still show Manual 5, but it's switched to automatic and I have to move the gear lever across to drive and back again to take control.

Thanks

Karl.

It could be your TCU. Try doing the transmission oil change along with new seals. I did my oil and seals change before i did XHP.
I don't think it's that serious if the rest of the gear change is working.

[Hawaiian340i]

Originally Posted by Hawaiian 335i

It could be your TCU. Try doing the transmission oil change along with new seals. I did my oil and seals change before i did XHP.
I don't think it's that serious if the rest of the gear change is working.

Try this

[Bimmer_Engineer]

How often could you possibly have an opportunity to do a 4-5 upshift at WOT? Please post an alert when you’re planning to be out on the road...

[dogtanion]

Thanks for the replies! Good video on refurbishing the mechatronics.

Found a potential replacement working gearbox from a breakers from a 2007 335i for a very reasonable price, which might be easier.

Spoke to my local 'stealer' who said I can not use any gearbox from any other car on my car and I have to buy a new mechatronics unit from BMW for £900.

Can anyone confirm that this is b*llocks ?

I've got the 'ProTool'. If I swap the transmission, what do I need to do to make it work with my car ?

Are there any known issues with swapping a 2007 auto transmission from a 335i into a 2008 ?

I can see the HW versions are different.

Thanks.

[MyN52willBEATyou]

Did you resolve this issue without a transmission swap?

My 2006 330i is doing this same exact thing except it hasn't thrown any codes because I rarely push on the car harder than needed.

I've only experienced this very badly when accelerating onto the freeway at 75-100% throttle but it's bad enough for me to know there is an issue.

[Asreegan]

Originally Posted by MyN52willBEATyou

Did you resolve this issue without a transmission swap?

My 2006 330i is doing this same exact thing except it hasn't thrown any codes because I rarely push on the car harder than needed.

I've only experienced this very badly when accelerating onto the freeway at 75-100% throttle but it's bad enough for me to know there is an issue.

Originally Posted by MyN52willBEATyou

Did you resolve this issue without a transmission swap?

My 2006 330i is doing this same exact thing except it hasn't thrown any codes because I rarely push on the car harder than needed.

I've only experienced this very badly when accelerating onto the freeway at 75-100% throttle but it's bad enough for me to know there is an issue.

Managed to resolve? Having the same issue but mines a N54 motor

[ThatRWD]

Having similar issues w/ an 07 335i auto. Running XHP Stage 3+ and MHD stage 2+. 133k miles.

Car makes what sounds like a hissing sound when shifting from 3rd to 4th when doing normal cruising/driving. If I go WOT and the car has to shift into 4 then it will do so but then it jumps to 3rd or 5th and then 4th and then throws a transmission error and stays stuck in what it claims to be 4th but feels more like 3rd. If I put the car into manual it's less likely to happen.

[pagnifeli]

Did anyone solve this problem?? I have same problem in wot on my 325i 2006

[tryingtobebest]

Same as above, anybody have any updates on this? Links would work for me!

[e90330ikid]

Since no one is updating this I will be in he next couple weeks, having the same problem with my 4th gear on my 09 335i so im gonna replace the seals and do a filter and fluid change to see if that fixes it if not, then I’ll do the shift solenoids and update y’all

[Capt_T83]

Hi everyone,
I have exactly same issue with my 2009 330i e93, feels slipping between gears 4 and 5 only and mainly under load…
Took the car this morning to a garage who only specialise in auto gearboxes and he’s saying that I’d need a total refurb and quoting £3200+VAT.
His reports shows codes 4F85 (EGS: Ration monitoring, clutch E) and code 4F8A (EGS: Ration monitoring, gearshift 4-5).
Not sure what you guys think…is he taking me for a ride and this is loads of BS or is he genuine???
Appreciate any feedback you can give on this.
Thanks

Tarek

[Yeahbuddy]

Originally Posted by e90330ikid

Since no one is updating this I will be in he next couple weeks, having the same problem with my 4th gear on my 09 335i so im gonna replace the seals and do a filter and fluid change to see if that fixes it if not, then I’ll do the shift solenoids and update y’all

Any news mate?

[ulissestoga]

Originally Posted by e90330ikid

Since no one is updating this I will be in he next couple weeks, having the same problem with my 4th gear on my 09 335i so im gonna replace the seals and do a filter and fluid change to see if that fixes it if not, then I’ll do the shift solenoids and update y’all

My 135i N54 ZF 6hp21 transmission had error 4F84 (Gear Ratio Monitoring Shift 3-4). Always when changing from 3rd to 4th the transmission went into emergency and locked in 3rd gear.
The oil, filter, seals, clutches and valve body with solenoids were changed. I bought a new TCU, but it was defective, so today I use the car's original TCU.

Now the car changes all gears normally if it goes slowly, but if it requires a little, the transmission goes into emergency, most of the time showing only the error 4F8A (Gear Ratio Monitoring Shift 4-5), and sometimes only the error 4F85 (Gear Ratio Monitoring Clutch E), these errors never appear together.

I've studied a lot about this exchange rate, but I still need help.

What hypotheses do I suspect are causing the problem:
- Low oil level (I don't know if the mechanic completed it according to the ZF/BMW manual)
- A problem with a solenoid
- TCU with problem

Any idea?