I have no idea how this happened, but I reset the timing on my Z/28 (it was like 4 above TDC) and now I'm getting check engine code 25, manifold temperature sensor. I refuse to believe that the events are unrelated considering I had no trouble before. Anyone have an explanaion?

 

The MAT wiring runs right past the dizzy. You probably pulled a wire loose or something. Hopefully it's not the connection to the sensor itself...you have to pull the plenum to get to it (it's on the bottom.)

 

Its not disconnected from the plenum, but I wouldn't be suprised if a wire is lose somewhere. Its an intermittant code but the SES light is on more than its off, especially when moving.

 

There's another 2-pin connector where the MAT wiring comes out of the harness, right behind the dizzy. Check that one.

 

Right by the connection near the main harness, the insulator of both of the MAT wires was burned off leaving them exposed. I think when I was setting the timing, I moved the wire and it was resting on the head. They were either shorting each other or shorting to the head itself. Either way, I wrapped them individially in electrical tape and the problem is now fixed.

I had some other issues today as well. When I tried to start the car this morning, it would start then die. After checking electrical connections, vaccuum connections, timing, and fuel pressure, I realized that the vehicle would run if I had the throttle at anything except fully closed. I then placed a penny between the throttle and where it rests and the car would stay started. What do you think this is being caused by? I found and fixed a vaccuum leak before setting the timing so I think the idle was being controlled that way. Maybe the IAC is bad? How would I confirm this? Thanks.

 

The IAC is a very likely possibility. Pull it out and clean the pintle and seat (it probably needs to be done anyway) and see if that doesn't help. You might also want to clean the throttle bores while you're at it. I find that carb cleaner and a toothbrush work very well.