Can't Figure out P0108 Problem
 

Hey, I'm new to the forum, and I'm looking for some tips and help for my issue I'm having with my Fit. It's a 2007 1.5L automatic sport.

Problem: After I did a valve adjustment, I put everything back together and started the car. It surged up and down- to 3000 rpm and back down, I turned it off. I started it again and then it stalled out after a few seconds of the same thing. It threw code P0108 - MAP Sensor High Voltage. Also, I should mention there were no engine problems beforehand.

Now I did some diagnosing. With live data from a scan tool and key on engine off, the map sensor read about 56 in. Hg. I unplugged the sensor and it still read this same number. Because of this, I believe its an electrical short in the MAP circuit.

Here's what I then found out with some more diagnosing:
-MAP Power wire (multi meter black probe on metal ground and red probe in connector port to the power wire): 5V
-MAP Ground wire (black probe on wire, red probe on battery positive, battery was a little low on juice): 10V
[also, the battery was charged when I started the car after the valve adjustment]
-MAP Signal wire (red probe on wire, black on metal ground, key on engine off): 5V
-MAP Signal wire (same thing, but I checked at the PCM): 5V

As far as I know, these results seem to indicate that the system is working right electronically. I don't think its the PCM, because that had no issues before the valve adjustment. I would be so grateful for any help. I can provide more details if needed. This leaves me totally stuck at the moment.

Before you go on a wild goose chase, I'd go through and look at all the hoses around where you were working, checking for cracks or disconnections. A surging idle sounds like a vacuum leak. If you can't find anything, re-check your valve clearances. It's very suspicious that this appeared immediately after a valve adjustment. I'd closely follow along with a video like this one (turn on closed captioning to see the instructions):

Should use scanner wit live data and look at the MP reading
Typical reading at warmed up idle should be 26 to 27 KPa; higher number = low vacuum messed up valve adjustment, misplaced plenum gaskets or disconnected brake booster line