Auto gearbox problems

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i had a similar problem with my gearbox especially 1st to 2nd i replaced my fusebox and all the relays and what a transformation gearbox is smooth as silk and what is also strange is the engine has become more powerfull and responsive:)
 
6704nathan said:
i had a similar problem with my gearbox especially 1st to 2nd i replaced my fusebox and all the relays and what a transformation gearbox is smooth as silk and what is also strange is the engine has become more powerfull and responsive:)
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Thats interesting, I will pull the fuse box apart and look. Currently I'm tracing the wiring through:)
 
Well I no longer have a lot of confidence in RAVE wiring diagrams, the actual wiring on my auto box ECU is nothing like the RAVE drawings. It makes following the wiring through a slow process. If RAVE is accurate, there is no demand for torque reduction when the box shifts as the pins in the connector specified for this are not there.... Need to find more info on the Bosch EAT ECU.
 
what are your actual symptoms and what was oil like , and did it start after something like oil change or just come on, diesels do go through one way cutches which can start by not catching imeditely and slipping a bit before catching
 
jamesmartin said:
what are your actual symptoms and what was oil like , and did it start after something like oil change or just come on, diesels do go through one way cutches which can start by not catching imeditely and slipping a bit before catching
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One day it was good, next day it was not. Symptoms are a rise in engine revs on 1st to 2nd and 2nd to 3rd, 3rd to 4th is fine. Down shifts are fine. No evidence of slip when held in third. At same time I found the underside covered in diesel after a mouse ate the leak off pipes, so been looking at the wiring for damage.
I've drained the oil twice, no change. The first lot of oil came out reddish brown but with no particulates.
I have a feeling you are right about the one way clutch.
However I also suspect that there is a generic wiring fault on P38's which means there is no engine torque reduction on shifts. That would account for the higher failure rate of auto boxes on diesels.
I'm trying to source Bosch connector details for the engine ECU and EAT ECU to confirm the wiring for torque reduction demand and confirmation.
Any info welcome:)
 
300 tdi ,td5 ,the same,if it is one way clucth its located near front of box in clutch c ,can be changed by home mechanic with some instruction,oil would seem to suggest just normal old oil,sometimes oil change can bring fault on,i would be intereseted to know what you find about ecu etc
 
jamesmartin said:
300 tdi ,td5 ,the same,if it is one way clucth its located near front of box in clutch c ,can be changed by home mechanic with some instruction,oil would seem to suggest just normal old oil,sometimes oil change can bring fault on,i would be intereseted to know what you find about ecu etc
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Once I have gone through all the electrical options, if it's still U/S, I will gird my loins to change the box. I have a spare in my 96 spares dog. Going to compare the wiring between the 96 and the 00 to see if they are the same.
 
Well I finally got my head round the wiring, regretably it's all OK, even the inside of the fuse box looks like new.
I also found information about doing a stall test, the box fails.
Of all the things I expected to fail on the P38, the gearbox was way down the list, I've always thought ZF boxes were pretty reliable, I've had them on other vehicles that have topped 300K miles. I reckon that the ZF4HP22 is marginal for the P38. It's really my worst nightmare.
I've removed the PSI Power Box, that has disguised the problem, 1st to 2nd is fine with the reduced power, 2nd to 3rd over revs a little sometimes.
Maybe the power box is just too much for the gearbox torque rating.
 
Datatek said:
Well I finally got my head round the wiring, regretably it's all OK, even the inside of the fuse box looks like new.
I also found information about doing a stall test, the box fails.
Of all the things I expected to fail on the P38, the gearbox was way down the list, I've always thought ZF boxes were pretty reliable, I've had them on other vehicles that have topped 300K miles. I reckon that the ZF4HP22 is marginal for the P38. It's really my worst nightmare.
I've removed the PSI Power Box, that has disguised the problem, 1st to 2nd is fine with the reduced power, 2nd to 3rd over revs a little sometimes.
Maybe the power box is just too much for the gearbox torque rating.
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sorry to hear the box is no good,i cannot see it being the powerbox tho data as there are many p38's with this fitted and with no problems reported.
 
gemsdad said:
sorry to hear the box is no good,i cannot see it being the powerbox tho data as there are many p38's with this fitted and with no problems reported.
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I reckon the increase in torque from the power box pushes the limits of the auto box and maybe shortens it's life. It's off for the moment as the car appears useable without it:) There are quite a few threads with clutch failures.

The good news is a mate is coming to dig a service pit in my barn in 2 weeks which will make the job a lot easier. The barn is built on sloping ground so the pit will be open at ground level at one end to walk straight into from the back door, a couple of transmission jacks and I'm half way there:)
 
Datatek said:
I reckon the increase in torque from the power box pushes the limits of the auto box and maybe shortens it's life. It's off for the moment as the car appears useable without it:) There are quite a few threads with clutch failures.

The good news is a mate is coming to dig a service pit in my barn in 2 weeks which will make the job a lot easier. The barn is built on sloping ground so the pit will be open at ground level at one end to walk straight into from the back door, a couple of transmission jacks and I'm half way there:)
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glad you are having a pit dug,not only will it enable you to work on your vehicles.but when your doris gets on your nerves you can always tell her that the pit has other uses,;);)
 
jamesmartin said:
changing one way clutch isnt too hard but it is very common on diesels
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I can do without the car for a while, the plan is to take the box out of my spares dog and fit it as is after changing the oil and filter. The duff box I might have a look at on the bench but I have no expertise on auto boxes. What I will probably end up doing is taking it to Ashcroft's next time I'm in the UK for an exchange re-con unit.:(
 
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