ambient air temperature sensor problems

mctator · Wed Jun 22, 2016 3:12 am

my 2010 2.4L automatic is having a malfunction with the ambient air temperature reading on the instrument panel display. When I first start the car the temperature reading is accurate, then after a few minutes of driving the reading is typically 12 degrees F above actual outside air temp. Stopping and restarting the car resets the temperature to the accurate value. I had this problem with my 99' grand prix and it was the infrared thermometer on the dashboard.
Is there a separate temp sensor for the ambient air than there is for the intake air temperature? if so, where is it located?
using my obdII scanner the intake air temperature reading is consistent with the actual temperature.

On a possibly related issue, I was driving to Colorado this last weekend and had issues with throttle response and cruise control. We were driving hard, running the ac, and the outside temp was 90 F+, barometric pressure at 13.8 psia. I was using the cruise control and it was running fine. I turned it off to slow down, and it would not work when i tried to set the speed. My throttle response severely dropped off as well. with the pedal all the way to the floor the car would not go faster than 60 mph. Also, the car would not let me 'manually' shift below 6th gear. I had my scanner plugged in so I checked the live data. Everything seemed inline except the throttle position would not go above 50% with the pedal all the way down. MAF was in range and so was AFR commanded and measured. Intake air temperature was in range as well. There were no DTC's set. We were low on fuel so we pulled off to top off. While we were waiting I checked the oil and transmission fluid levels and there were right on. After we were done fueling we drove the car around the town a bit. The throttle response returned to normal and I had full control of the transmission.

My first impression was that the air temperature sensor was having difficulty due to the high under-hood temperature. We got back on the highway, reduced speed, and turned the AC off. The car ran fine the rest of the trip there. On the way back to Missouri we drove at high speed and ran the AC hard. We did not have any trouble on the return journey. My other thought is that the throttle plate could be dirty and combined with some thermal expansion could cause the plate to jam in position which could have caused the throttle response issue. I've inspected the throttle plate and it does not appear dirty, but I still intend on cleaning it with throttle body cleaner, and cleaning the MAF sensor with MAF sensor cleaner.

All in all I'm wondering where to go from here that doesn't involve a dealership. I really appreciate all of your knowledge and help. Thanks guys

Wed Jun 22, 2016 1:40 pm

Hello and welcome. What condition is your battery in? Lots-o-weird crap goes on when batteries in these cars start to head south.

mctator · Wed Jun 22, 2016 1:58 pm

did a simple load test with my multimeter and everything seemed fine. Hadn't had any problems starting before but I'll take it out and give it a proper load test at my lps.

LPSISRL · Wed Jun 22, 2016 4:46 pm

My first thought is a faulty throttle position sensor. Especially since the data says that it wasn't going past 50% when you knew it was.

mctator · Wed Jun 22, 2016 4:58 pm

The readout for the pedal position was accurate, but there was not an equal throttle command. after I got home I did the Suzuki service manual tests and everything came back alright. It also never set a code the whole time which was odd to me. The relative throttle position was close to the top of it's range but I'm not sure what that value really means. Another odd observation was that as soon as I exited the highway the throttle response returned to normal. It makes sense to me that the tps sensor and motor could be faulty but typically those set codes.

Wed Jun 22, 2016 6:40 pm

The ambient temperature sensor is located at the front of the car. I've seen it a few times before when the front bumper was off. Maybe it needs a cleaning?

As for the other issues, I'd try disconnecting the battery for while and then reconnecting to see if that resets things to make the odd issues go away. If they reoccur, it's then time to investigate further.