MAF related nightmare?

jamiemaitland

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Hello chaps, awesome forum by the way, I have always been floating around finding solid advice and never felt the need to post until now!
I own a w202 c200 automatic after catching the bug from a brief stint in a 190 a few years back and despite this car not being on the level of the 190 it has still been faultless until recently.
A few months back I discovered an issue with not revving past 4000rpm then misfiring afterwards along with codes being flagged which due to advice from this website I rooted down the MAF. After getting an extorionate price from the dealers and not being too fond of buying second hand I bought a cheap unit off ebay. The fault was cured and the car ran like a swiss watch once again. However after a few weeks I started noticing a warm start fault along with a slight but noticeable drop in power, so I read the codes and it gave me po100 which pointed toward the cheap MAF. So I bought another one believing it was a one off that just the one was faulty. I fitted it last night, took it for a small run and all seemed well. However this morning the car started stuttering, then lost all power and ended up on the hard shoulder after no more than 5 miles. I had it dragged back to my house, dug the old one out of the bin, yet all it does is start, run for a second then die with either sensor installed. There are no other faults stored on the car. All the wiring seems OK and I'm getting voltage at the connector. I can't see any splits or hear any leaks and theres no offending noises. I'm jus wondering if anyone here has any similar drama with cheap MAFs or if its just a bad coincidence and something else has reared its ugly head?
Thanks in advance,
Jamie
 
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television

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Hello and welcome, sadly Ebay cheap MAFs will only last a few weeks, you have no choice but to get a refund and buy a Bosch do ask ECP for a price.
 

LostKiwi

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Not sure on your engine but on many cars disconnecting the MAF will prove if thats the problem or not.
If it runs badly with the MAF but ok without then the MAF is the culprit.
 
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jamiemaitland

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Thanks guys, lostkiwi I tried running it without the MAF back in june and it would not run at all but it would even with the original defective one in place. I just rechecked the wiring and I'm getting battery voltage at the sensor and the earths are OK. I cracked off some sort of pressure relief valve on the injector rail and started it up and all OK there's pressure at the injectors also. Thanks malc, I'll source one and get back to you!
 

EdGasket

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I just cleaned my original MAF with contact cleaner (£4 from hellfrauds); made the world of difference; no more pinking and pulls much better in the higher numbered gears (I have a manual box). You do have to remove the MAF by undoing the 'security' torx bolts so you can get at the thing.
 
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jamiemaitland

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Little update, I managed to source a second hand bosch sensor and hey presto the car ran and the faults cleared! I took it for a little run and all seemed well, however when I left it to idle every thirty seconds or so the idle will plummet and almost stall then picks up to normal. There are no fault codes showing but when I was checking the live data the fuel sys1 shows 'FUEL OL' when this stutter occurs. Does anyone know what this could be? Or is it just a case of possibly the engine and ECU adapting to the new MAF as I read somewhere?
 

Uncle Benz

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It is customary to perform a "bootstrap" when replacing the maf on these models. Basically resets the ecu's adaptation to the old unit. Driving the car will also perform the same function, but it will take time. Give it a while and see what happens.
 

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