My car is a 1999 Bonneville SE....
I'm starting to transition slowly from a "check the fluids and change the oil" type of DIY'er to someone who, hopefully, can save a few more bucks by doing the next set of maintenance jobs myself (e.g. flush the coolant, check PCV, etc.). When getting ready to clean the throttle body this evening, however, I noticed that the air intake tube between the air box / filter and the throttle body had a dime-sized hole in it (pre-fab hole, not like someone stuck a screw-driver through it). Upon further investigation, it certainly looks like the exact position as the IAT in the photo this this thread (Intake Air Temp (IAT) sensor replace
). My car has been getting considerably worse gas mileage recently (26-27 mpg almost 100% highway with cruise 60-70 mph vs. 30-32 mpg I got year ago), but I attributed that to new tires.
My SES light came on a year ago, and the tech at the repair place said it was a code thrown for the vapor/evaporation system. He checked out the obvious places, but couldn't find anything, and I didn't want to pay for him to continue to hunt down a small hole somewhere. As such, for the past 12-14 months, my SES has stayed on. I've had the car in for some other work in that time (most recently about 3-4 months ago as a result of misfiring that required new plugs and wires, replacing ones that had ~80k miles on them), and the techs, when they've pulled the codes, haven't said anything about an IAT sensor error being thrown. Can they IAT sensor really be missing? Again, I can stick my pinky finger into the hole in the tube (located just beyond the air box and that metal screw tightener deal). I looked around that area for any dangling wires that would tell me that the sensor fell out and got ripped apart, but I didn't find anything.
FWIW, I started to look into doing some DIY maintenance because my idle the past month or two has been rough, particularly right after starting the car. After I start the car, the engine will idle around 1500-1600 RPM until I rev it or drive away. If I drive it immediately after starting it, the car "jerk"/hesitate a bit, though that usually goes away after 20-30 seconds. At any rate, all of this got me to start looking at cleaning the throttle body, which got me to notice the issue addressed in this post. Thanks!