V6 Autobox Replacement Problem

[mattux]

I recently had my autobox reconditioned for my 1996 V6 Galaxy

 

After this the range indicated by the trip computer (which is consistent with the mileasge covered) was reduced to 260 miles which I think approximates to 16 mpg (?) compared to an average of 350 before replacement

 

The box and the torque convertor were replaced. the only issue noted was that a wire had been pulled out which stopped the speedo working and this had to be 'shorted across' the connector block on the back of the engine due to inaccessibility

 

Does anyone have a view on the likely cause please ?

[Ivor_E_Tower]

If the gearbox ECU isn't getting the correct speed info, it may be changing up too late hence the extra fuel use. Could also be increased internal friction in the recon box, which may reduce over the next few thousand miles (but unlikely to be this).

[GSMGuy]

Did they recon your OWN box or fit one off the shelf? As there is the possibility for instance that they may have fitted one from say a 2.0 which will have a lower final drive - or even put the wrong final drive back in your box... Does the engine seem to be revving faster for a given speed? Maybe another V6 owner could post what revs/speed they are getting for comparison??

 

Mike

[mattux]

Thank you for your prompt replies

 

l don't know about the ECU input data but they certainly had an issue with the speedo connection.

 

It was my gearbox that was reconditioned apparently. It does seem to accelerate faster but then it was fairly rough before. On this point I can confirm that low fluid levels will cause a late and hard change.

 

I have had comment that it could have been assembled wrongly such that it did not change up early enough but I think this would need to be benchmarked objectively to prove this in different conditions.

 

Average ranges from other comparative vehicles would be useful here - maybe the problem was before rather than after ?

[Denis]

As far as revs go, 70mph = 3000 rpm on mine.

[GSMGuy]

As far as revs go, 70mph = 3000 rpm on mine.

Jeez, no wonder they drink the juice lol... about 2250'ish on mine :lol:

 

Mike

[Dally]

As far as revs go, 70mph = 3000 rpm on mine.

That's about right for me too!

[johnb80]

Whilst not knowing the full system on the V6 Gal, without the correct speed pulse it's very likely that the torque converter won't lock up in 3rd and 4th gear which would result in a much higher thirst and higher revs.

#

Regards - JB

[mattux]

Mine appears to be at about 3250 at 70 but I am on a 4 speed box

 

Interesting point on the speedo sender

[mattux]

I've checked the milometer reading and it appears to be spot on. I cannot detect any slippage i.e. movement in tacho vs speedo in 4th gear.

 

Does anyone have any further thoughts as the drop in mpg is very large without it would appear any explanation ?

[Ivor_E_Tower]

Newly rebuilt box has higher internal friction than "worn" old box, so more energy required to overcome resistance to movement, hence worse fuel consumption. However, if it is as drastic as you suggest, maybe something is not right?