When my engine (just past the 50,000 mile mark on my 2009) is fully warmed up and idling (~800 rpm; everything off radio/fans/AC/etc), my MAF is reading 4.1-4.4 grams/second, and my LTFT are +12. Pretty standard symptoms of a vacuum leak (there is also an audible high pitched "chirp" that sounds like a vacuum leak as well).
So far I've cleaned the MAF (wasn't visibly dirty to begin with but what the hell) and re-set the fuel trims - no change. Cleaning the throttle body, which was slightly oily, also had no affect (curiously, calculated engine load at idle went from 30-33% to 29-31%, and the MAF readings started to hit 4.1 more often). Tried to track down any vacuum leaks myself, couldn't find any, so I took it to the dealer to get it smoke tested. The smoke test didn't turn up any leaks. I spoke with the tech at length, and he insisted that it was the P0420 being thrown by my midpipe that was adjusting the fuel trim. When I postulated how this could possibly cause the MAF to read lower than normal he provided an incoherent response in which he referred to the car's "4 cylinder" engine and rich smelling exhaust. He also said that the MAF itself shows no signs that it is faulty or has any frayed wiring.
So my question is where do I go from here? The only other "clue" is that on 3 occasions this summer on hot days, when the car was repeated shut down/restarted in rapid succession with the engine hot (such as getting gas, then going 1 mile to the pharmacy, then going 2 miles back home), I would get a P0111 as pending. On all occasions the P0111 would clear itself within a day or two and never went beyond "pending" status. Monitoring the intake temperatures revealed no abnormally high/low readings under normal driving conditions (10-15 degrees F over ambient).
Thoughts? All I can think of is to re-check the grounding for the MAF. :banghead:
UPDATE: Just made this connection - the high pitched "chirping" that I previously mentioned sounded like a vacuum leak goes away when I push the clutch in. It then returns almost exactly 3 second after the clutch pedal is released.
So far I've cleaned the MAF (wasn't visibly dirty to begin with but what the hell) and re-set the fuel trims - no change. Cleaning the throttle body, which was slightly oily, also had no affect (curiously, calculated engine load at idle went from 30-33% to 29-31%, and the MAF readings started to hit 4.1 more often). Tried to track down any vacuum leaks myself, couldn't find any, so I took it to the dealer to get it smoke tested. The smoke test didn't turn up any leaks. I spoke with the tech at length, and he insisted that it was the P0420 being thrown by my midpipe that was adjusting the fuel trim. When I postulated how this could possibly cause the MAF to read lower than normal he provided an incoherent response in which he referred to the car's "4 cylinder" engine and rich smelling exhaust. He also said that the MAF itself shows no signs that it is faulty or has any frayed wiring.
So my question is where do I go from here? The only other "clue" is that on 3 occasions this summer on hot days, when the car was repeated shut down/restarted in rapid succession with the engine hot (such as getting gas, then going 1 mile to the pharmacy, then going 2 miles back home), I would get a P0111 as pending. On all occasions the P0111 would clear itself within a day or two and never went beyond "pending" status. Monitoring the intake temperatures revealed no abnormally high/low readings under normal driving conditions (10-15 degrees F over ambient).
Thoughts? All I can think of is to re-check the grounding for the MAF. :banghead:
UPDATE: Just made this connection - the high pitched "chirping" that I previously mentioned sounded like a vacuum leak goes away when I push the clutch in. It then returns almost exactly 3 second after the clutch pedal is released.
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