What does the MAF actually do?

Well if they think the vanos is sticking, the first thing they should be doing is cleaning the vanos solenoids. Quick, simple and cheap.
 
Yeah I agree. However I have renewed both vanos solenoids so again not convinced. In my mind I'm thinking something is causing the knock sensors to fault code, these faults then cause the car to alter its timing slightly which causes the lumpy acceleration. So maybe shiity oil or poor fuel delivery could be the root cause creating the "knock". Willing to give the flush a good go despite the garage I bought it from claiming they serviced it before I picked it up. Was hoping this performance garage could see more definitely from their hi tec diagnostics equipment what area was at fault. Anyway, driven 50miles in it today with the engine flush in and I've just recorded the best mpg since I've owned it (30.7mpg), this is a commute journey which previously the best was 28.5mpg, so maybe something is shifting?
 
Naylz said:
Yeah I agree. However I have renewed both vanos solenoids so again not convinced. In my mind I'm thinking something is causing the knock sensors to fault code, these faults then cause the car to alter its timing slightly which causes the lumpy acceleration. So maybe shiity oil or poor fuel delivery could be the root cause creating the "knock". Willing to give the flush a good go despite the garage I bought it from claiming they serviced it before I picked it up. Was hoping this performance garage could see more definitely from their hi tec diagnostics equipment what area was at fault. Anyway, driven 50miles in it today with the engine flush in and I've just recorded the best mpg since I've owned it (30.7mpg), this is a commute journey which previously the best was 28.5mpg, so maybe something is shifting?
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Hi Naylz, did you ever get this issue sorted? Similar issues with mine and I'd love to know if you found a solution :)

Cheers!
 
Some more diagnostics required on this, with engine running view the fuel trims, if they are high then suspect the Maf or air leaks in the vaccum system rubbers and pipes, check for splits. If its seeing a mismatch between the Maf and what the exhaust sensors are picking up it will think its running lean and demand more fuel at the injectors, disconnecting the Maf connector will cause the engine management to run on default settings, if the car runs better thats another clue to the Maf being bad. Cleaning the Maf sensor with Maf Cleaning Spray could fix the issue but if its duff thats not going to fix it. Do not buy cheap ebay replacements always go for oem brands Bosch or Seimens were oem brands.
 
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