CEL on, maybe not MAF???
05-27-2004, 08:24 AM
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me: 2015 SL400 & 2015 ML400; wife: 2022 GLC Coupe kid: 2017 GLC SUV
CEL on, maybe not MAF???
well I'm gonna post this query here due to all the fine, upstanding, knowledgeable folks subscribed. My w202 ('00 C280 Sport) cel came on. I assumed it was the maf, and my trusted independant mechanic (owner of 3 MB's and servicer of many) had one in his shop. Different numbers but looked same, came off an ML. I took the car for a spin, punched it, and it coughed, sputtered and limped back to the shop. Put the old maf back in and it was fine. I bought a maf on ebay (with a PayPal money-bak guarantee!) of the correct model number, put it in myself, did the same test drive, and got the same result. Put the old maf back in and it's fine (cel still on, however). Can I deduce anything of value from this experiment? The computer that my tech plugged in (not an MB) indicated fuel mix malf, if that helps.
06-10-2004, 07:20 PM
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LS7 powered Corvette
If it says, mixture malfunction, most likely the adaptation values are maxed out at either "idle" or "part load." For example the base point in the control unit may be 0.000 while fully enrichened due to a detected lean condition would be around 1.2 and leaned out would be -1.2.
You are probably looking at an air leak somewhere, bad injectors, clogged fuel filter, or the MAF. If you have the light on but no obvious signs of poor engine performance, I would be looking at the air leaks. Main culprits on the 112 engine, V6, tend to be the two seals on the elbow underneath the air mass. The crank vent hoses to the valve covers also become brittle, or I have even seen the purge valves for the EVAP system hang open creating a vacuum leak. Good luck!!
You are probably looking at an air leak somewhere, bad injectors, clogged fuel filter, or the MAF. If you have the light on but no obvious signs of poor engine performance, I would be looking at the air leaks. Main culprits on the 112 engine, V6, tend to be the two seals on the elbow underneath the air mass. The crank vent hoses to the valve covers also become brittle, or I have even seen the purge valves for the EVAP system hang open creating a vacuum leak. Good luck!!
