I'm currently ripping apart my l98 engine and sorting through some issues and performing some diagnostic work, and I've hit a bit of a wall. While breaking down the air intake assembly I found that there was two sensors on the lower manifold that go into the coolant passage on the manifold, as far as I know, the one on the right is the coolant temperature sensor that feeds information to the computer, but I'm a bit stumped as to what the one on the left is. I found that the sensor was unplugged, so at first I was rejoicing because I believed I found my drive-ability issue, I thought that my engine thought it was -50 degrees out all the time and that it was dumping fuel into my engine, but upon further research I realized that the sensor is not for the coolant temp. I found a connector unplugged and taped up under the upper part of the intake and i figured the two went together, but they don't fit together. I was wondering if anyone knew which sensor is located on the left side of the intake manifold and goes into the coolant passage near the thermostat and what that plugs into? Thank you!

 

The sensor on the front of the intake is a timer switch for the ninth injector.
Red one is timer switch blue is cts. If you run 89 programming or go to speed density this is not needed.

 

I came across that picture myself as well, but my sensors are in the reverse order, my engine mine is a 92, so as far as I know I have speed density. So you think I don't need this sensor? I remember scanning for codes and getting a coolant sensor malfunction code so I"ll probably go ahead and switch out the sensor while I"m in there, but as far as the other sensor goes I should be okay leaving it unplugged? Thanks!

 

Since your running as you don’t need the timer switch and can plug the hole with the switch or with a npt plug 3/8 iirc.