Also, made an error on a previous post. Pin 1 to pin 3 with connector off map sensor registered 4.6v with key on run, engine off.

Reconnected connector to map sensor and got 5.19 from dg/rd (+) to br/y (-)

 

At warm idle when (+) is connected to dg/rd and (-) is connected to br/y, I get 1.7v at idle and it drops to about 1.1 at light load, and less than 1v at a heavier load. Does not sit at 1.3v.

Sorry for all the separate posts, I'm going through all the steps again to make sure I'm not missing something.

 

Now Im getting new codes. P0107 is gone, now I get a p0108 - manifold absolute pressure/baro sensor high input, and also a p1296 - no 5 volts to map sensor. Wtf?


Also, after the short drive to O'reillys for the code scan, when I connect the voltometer while engine is running and warm(er) I'm getting 1.51v when the (+) lead is on DG/RD and (-) lead is on BR/Y.

 

You said: "At warm idle when (+) is connected to dg/rd and (-) is connected to br/y, I get 1.7v at idle and it drops to about 1.1 at light load, and less than 1v at a heavier load. Does not sit at 1.3v."

What "Load" are you referring to? If the Jeep is sitting still as you open the throttle there is little load on the engine and the vacuum should decrease only slightly. When driving the Jeep there is a load on the engine and the vacuum should decrease (voltage increase) as the throttle is opened, especially when the throttle is suddenly opened or when you are climbing a hill. In cruise the load evens out pretty much. If you had a vacuum gauge hooked up to your intake manifold and drove the Jeep around you could see what I mean.

No load=high vacuum=low voltage

High load=low vacuum=high voltage

Reassemble everything. Go to O'reilly and rent a scanner (you should get your deposit back when you return it) that can read live data, check for pending codes, delete all codes....

With the scanner plugged in to the DLC and key to RUN/engine off, look at MAP KPA (or Hg), this is the ambient barometric pressure sensed by the MAP sensor and signaled to the PCM. Start the engine and look at the MAP reading, as the engine warms up to operating temp the MAP readout will drop and settle down. This is the no load vacuum sensed by the MAP and signaled to the PCM. Drive the Jeep and watch the MAP readout and see what it does when you punch it - MAP will decrease as the engine load increases. All this if the MAP sensor is working properly and signaling the PCM properly.

If a CEL pops up while watching the live data on the scanner you will know what happened, and when....if you can catch it.

If there is no MAP reading on the scanner with key RUN/engine off and with engine running, try wiggling the MAP wire harness (all the way back to the wire harness manifold above the fuel injectors) and see if the reading changes. You'll see where the MAP harness crosses over the intake manifold-there could be chaffing in this area.

 

By "load" I just meant not moving, but giving it some gas.

I think I did move those pins when I probed the sensor connector. I "bent" them back and the light went off. Idles real bad and still the heavy hesitation. What are the chances I bought a dead MAP sensor?

 

If you suspect that you damaged the MAP sensor maybe you should replace it, but get a reliable one from the dealer or NAPA - at minimum, get a BWD sensor.

Did you inspect the harness where it passes over the intake manifold?

Have you attemptd to get a scanner and check it out using the live data feature....and check for pending codes?

 

I haven't had time to run more tests yet. Work gets in the way, and by the time I get home, get to the gym, have dinner, and am ready to look at it, I'm ready for a beer or 6.

I have already replaced the MAP sensor when all of this started with a BWD sensor from O'reillys. I'll get the live scanner and inspect the wires hopefully tonight. I'll report back with what I find.

 

Didn't have time to play with it last night... Hopefully I get to it over the weekend.

 

For some closure, I'm fairly certain this turned out to be a wiring harness issue. I haven't found the exact wire yet, but the bend that the cluster of wires takes into injector rail had caused chaffing over time, and one of the wires in that cluster is "loose". I jiggled that cluster of wires around, and the Jeep runs normal now with no issues. Now I just need to find the wire... It has to be the 5v signal wire right?

 

The fix:

https://www.cherokeeforum.com/f2/eng...1/#post1984446

If anyone has this issue, read that thread, and the thread linked in that other thread. That solved my issue.

 

I'm having the same issues as you with my XJ! I have the same P0107 and I have 5V at the sensor. I have replaced the sensor and no change. I tried to wiggle the harness where you said and I can't get it to go away or drive normally on the highway. The link you provided no longer works and I'm really curious as to what you did for the fix. Did you replace the harness or run a new wire front the ECM to the map sensor? Please let me know! Thank you!