Recently I've been noticing intermittent, large (+10 to+15%) jumps in short term fuel trims on throttle tip-in which return to ~0% immediately after. Previous smoke tests have failed to find any vacuum leaks, but using isopropyl alcohol I was able to find, and fix, a small leak in the upper intake manifold.
While looking around under the hood while waiting for the oil to drain, I found a second vacuum leak, this time in in VFAD hose, which I subsequently fixed. Initially, there was a modest improvement in MAF readings (average of 4.7 grams/sec, compared to 4.4 grams/sec previously - fully warmed up engine at idle). After another 5-10 minutes of driving the short term fuel trims shot from ~0% to +25% and stayed there. When I got home, I let the car idle in the drive way and watched the MAF reading. The MAF was wildly inconsistent, starting out around 5.0 grams/sec, and then dropping to 4.7 g/sec for awhile before taking a dive down to 3.7 g/sec (engine RPM 820-850). After shutting the car down I checked for any pending codes and found a P2097 pending.
I'm starting to question if the MAF may need to be replaced, as cleaning it did not result in any change. [Side note - can I use a series 1 MAF to see if it rectified the issue in my series 2 car? I'm not aware of any local series 2 owners, only Series 1.]
Ideas, suggestions, and comments are greatly appreciated. I'm game to try and double check anything before taking the car to Mazda, since the last time all they did was give me was a big bill and couldn't do anything to solve the issue. :confused:
While looking around under the hood while waiting for the oil to drain, I found a second vacuum leak, this time in in VFAD hose, which I subsequently fixed. Initially, there was a modest improvement in MAF readings (average of 4.7 grams/sec, compared to 4.4 grams/sec previously - fully warmed up engine at idle). After another 5-10 minutes of driving the short term fuel trims shot from ~0% to +25% and stayed there. When I got home, I let the car idle in the drive way and watched the MAF reading. The MAF was wildly inconsistent, starting out around 5.0 grams/sec, and then dropping to 4.7 g/sec for awhile before taking a dive down to 3.7 g/sec (engine RPM 820-850). After shutting the car down I checked for any pending codes and found a P2097 pending.
I'm starting to question if the MAF may need to be replaced, as cleaning it did not result in any change. [Side note - can I use a series 1 MAF to see if it rectified the issue in my series 2 car? I'm not aware of any local series 2 owners, only Series 1.]
Ideas, suggestions, and comments are greatly appreciated. I'm game to try and double check anything before taking the car to Mazda, since the last time all they did was give me was a big bill and couldn't do anything to solve the issue. :confused:
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