I drive a 2011 Chevy Malibu LT (4 cyl, 2.4L, 6 spd. automatic) and have been experiencing this problem for the past year and a half. Basically, whenver its
hot (90f+) and humid out, my car exhibits loss of engine power between 2100 and 2500 RPM. Its a very strange problem that is hard to reproduce so I haven't taken it to a mechanic, I'd like to tackle it.
If I'm gently accelerating, I'll hit somewhere between 2100 and 2500 RPM and the RPMs will drop to 2100 and bounce back up to 2500, repeatedly, as if I'm tapping the gas in ~1 second intervals. If I continuously but gently apply more throttle, it seems to have no effect until the point where the car actually downshifts to accellerate hard. Once the vehicle downshifts, I'm up above 2500 RPM and running fine. Once I hit that same RPM range again, the problem reoccurs.
Another thing to note, my average MPG reads 21.5 on a vehicle that should get 26/33 MPG. Then again, I drive pretty hard.
- This only occurs between 2100 and 2500 RPM
It must be over 90 degrees f. outside
- It must be humid
- It occurs in all gears
- No apparent sputtering
- RPMs bounce from 2100 to 2500 as if I'm tapping the gas
- No check engine light
- This problem never shows up in the winter
I think the first thing Im going to do is clean my MAF. I also think some other possible causes may be my O2 sensor and ECM.
What do you guys think? Has anyone encountered a problem like this?
Update: Cleaned MAF sensor, issue still persists.
Update 2: Today it was raining and 80 degrees and the problem happened again. I saw that my long-term fuel trim was actually at about -12 at idle and between -10 and -20 while driving. Normally my LTFT stays between -5 and 5. Any insights?
Update 3: Problem reoccurred today, it was only 64 degrees and had recently rained.
Update 4: I forgot to update this 3 years ago, but I sold the vehicle to a dealership and got a truck about a month after this post.