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Hard Starting, High Raving, Smoking And Wet Plugs.




Guest Pesin

My 2009 Corolla S has been doing hard starting. Now, when u start and and even while running, it raves high that the rpm is over 2. When u off it while the rpm is very high, it gets very hard to start and in most cases will not start atall. The plugs gets soaked in smelly fuel mixed with black smoke. If it starts, it smokes and smell so bad.

It does not smoke when running, only @ starting. I was advised to always press down the gas pedal completely while starting but that does not help!

Please help.

Sounds like it could be a number of things. Definitely looks like the plugs are either misfiring or you are not getting enough bypass air around the throttlebody to effectively start the car. The smoke on startup and hard to restart are mainly due to not enough air, wrong engine timing, or most likely - completely fouled plugs. Sounds like you are getting more than enough fuel - have to address the other aspects of the SFI system.

Depressing the accelerator when starting is a bad idea for most fuel injected systems and especially the DBW systems, unless you are trying to recalibrate them or to clear a fuel flooded engine. Sounds like the calibration is off on the DBW solenoid - depending on the level of offset - might have to bring it into a dealership to verify operation. Also double check the spark plugs - even though they are the long life iridiums - usually a good idea to pull them from time to time to assess condition and check plug gap.

Any CEL associated with the hard starting? When did this hard to start happen, or when did it suddenly get worse?

Guest Pesin

A recent scan detected weak maf sensor and oxygen sensor and misfiring in 2 cylinders. How do u think that can be resolved?

Did they provide the actual OBD-II codes by chance? Did they run a real-time out or capture any frame data when the car was running?

This car uses an air fuel ratio sensor instead of an O2 sensor - sort of like a high resolution/high performance O2 sensor. The MAF malfunction and faulty O2 sensor can cause much of the issues you are seeing, though for a 2009 model year, unless the engine was modded or otherwise played with or has an enormous amount of mileage on it - they should not have died this soon. Misfiring could be a symptom of the other two malfunctions. These also point to a possible ECM malfunction - though hard to say without some realtime data captured during operation or even a snapshot of an operational frame.

As for other possible culprits - there are number of them, from an ignition timing error, problem with the chassis grounds, faulty fuel delivery system or consistently bad tanks of gas, clogged or fouled injectors, etc.

ntermittent behavior like this is hard to diagnose, especially by a shop that doesn't have experience with this particular engine - Toyota dealers are usually your best shot, unless that particular shop is incompetent. If it was only the misfire, or MAF, or AFR sensor alone - that would make it easier to diagnose over the web - but all three makes it much more difficult, as they point to a number of possible culprits.

Definitely a time to take it to a competent shop. Car should still be under warranty - unless you ran over the 5yr/60K mile powertrain mileage portion. That case, it could be argued that the MAF and AFR sensor are essential for emissions requirements - as those are covered under the 8yr/80K mile warranty period. Definitely need to get this to a dealership to start a papertrail on it. I



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