Transmission flush , Air mass meter.

matrixabc · 02-17-2005, 05:08 AM

Im going to have my gearbox flushed out and new fluid replaced (£175.00), the guy said I dont need to change the filter because they flush out the whole system, unlike the dealer (£155.00) who will only drain off the oil and replace it, still leaving 40% old oil in the system ( so he says?!).
Also he told me I should change my air mass meter, as this can/will cause my gear box to fail if it causes it to start hunting? I have seen the posts on here, did the hunting eventually lead to gear box failure ??

Jkay · 02-17-2005, 05:29 AM

If it's clogged, then you're only doing half the job .

PaulW · 02-17-2005, 06:24 AM

ttuling · 02-17-2005, 11:41 AM

jwass posted last year how a bad mass air flow (MAF) sensor led to a 17114 incorrect gear ratio trouble code (usually meaning that clutches are slipping) from the transmission on his 2000 A8L, as well as multiple engine codes relating to fuel mixture. The slippage was probably caused by transmission line pressure being too low due to falsely low engine torque readings, to which the MAF sensor contributes.

Hunting -- a repeated locking and unlocking of the torque converter clutch at light throttle -- is probably not nearly as bad for the transmission as sustained slipping of other clutches, and unfortunately seems to improve only partially if at all after changing the MAF sensor.

I wouldn't think it urgent to replace the MAF sensor if there are no engine or transmission trouble codes relating to it. But that's based on the cross checking between MAF and oxygen sensor readings done in a US market car. If the self diagnostic programming is different on cars made to European emissions standards, maybe you get less or no warning before the MAF sensor starts to mislead the transmission, though I'd still hope the transmission would go into limp-home mode rather than slip egregiously.

If your mechanic has a specific reason to think your MAF sensor is bad, of course it should be replaced. But otherwise, I'd like to know how he justifies changing it as a preventive measure.

Tom

http://forums.audiworld.com/a8/msgs/59172.phtml

02-17-2005, 05:08 AM	#1
matrixabc New Member Account #: 62413 Join Date: Sep 2003 Posts: 175	Transmission flush , Air mass meter. Im going to have my gearbox flushed out and new fluid replaced (£175.00), the guy said I dont need to change the filter because they flush out the whole system, unlike the dealer (£155.00) who will only drain off the oil and replace it, still leaving 40% old oil in the system ( so he says?!). Also he told me I should change my air mass meter, as this can/will cause my gear box to fail if it causes it to start hunting? I have seen the posts on here, did the hunting eventually lead to gear box failure ??

02-17-2005, 05:29 AM	#2
Jkay Member Account #: 55364 Join Date: Apr 2003 Posts: 2,300	Yes flush is better than drain, but the filter is important too. If it's clogged, then you're only doing half the job . __________________ ------------------------------------- 18" 2006 Soft 5-Spokes - Goodyear F1s - Milltek Exhaust - Clear Sides & Corners

02-17-2005, 06:24 AM	#3
PaulW AudiWorld Super User Account #: 22012 Join Date: Jul 2001 Posts: 18,109	Agreed __________________ _________________________________ Paul Waterloo 01 S8 Black on Black Lots of Electronic Mods D2 A8/A8L/S8 FAQ Digest

02-17-2005, 11:41 AM	#4
ttuling Junior Member Account #: 11861 Join Date: Oct 2000 Posts: 950	Extremely bad MAF sensors can slip the transmission, not the same as hunting jwass posted last year how a bad mass air flow (MAF) sensor led to a 17114 incorrect gear ratio trouble code (usually meaning that clutches are slipping) from the transmission on his 2000 A8L, as well as multiple engine codes relating to fuel mixture. The slippage was probably caused by transmission line pressure being too low due to falsely low engine torque readings, to which the MAF sensor contributes. Hunting -- a repeated locking and unlocking of the torque converter clutch at light throttle -- is probably not nearly as bad for the transmission as sustained slipping of other clutches, and unfortunately seems to improve only partially if at all after changing the MAF sensor. I wouldn't think it urgent to replace the MAF sensor if there are no engine or transmission trouble codes relating to it. But that's based on the cross checking between MAF and oxygen sensor readings done in a US market car. If the self diagnostic programming is different on cars made to European emissions standards, maybe you get less or no warning before the MAF sensor starts to mislead the transmission, though I'd still hope the transmission would go into limp-home mode rather than slip egregiously. If your mechanic has a specific reason to think your MAF sensor is bad, of course it should be replaced. But otherwise, I'd like to know how he justifies changing it as a preventive measure. Tom http://forums.audiworld.com/a8/msgs/59172.phtml

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