air mass sensor problems

[keithg]

I have just replaced the mass air sensor on advice from vw garage at service myself on my 99 Golf TDI 90.

It has clearly improved the acceleration and power especially in lower gears but as soon as you hit 3rd it feels like it did before and the same problem in 4th and 5th. the engine also feels quite lumpy with flat spots now.

I have read some of the feeds about disconnecting the battery for 10 mins etc to reset the original ecu codes etc.

Any other suggestions ??

Thanks, keith

[Boardboy]

Hi Keith
I think you should leave the battery disconnected at least half an hour.
There are quite a few threads about it and how long the ECU takes to re learn everything. Is it a genuine MAF (Bosch or Pierburg) and not an E-bay special?
Regards Boardboy

[adamss24]

You may have a sticky VNT mechanism(the vanes jam due to carbon build up inside the turbocharger) . Will need taking the turbo off the car and open the exhaust side and clean with a soft paint brush. DO NOT use any abrasive or wire brush. Leave the exhaust side of the turbo to soak overnigt in a container with carb cleaner. Do a search on the forum as its been answered before. Another thing to check is the Charge control pressure solenoid -it controls the vane mechanism. Follow the small hose that goes from the turbocharger to the electric 3way valve. Replace with a known good one or have someone check if operating normally with a vag-com. Hope this helps.