MAP Sensor Troubles

For around the last week or so I’ve been having some troubles with the bird occasionally having somewhat violent misses in the motor.  I spent a few days trying to track down any vacuum leaks or other issues that I might have caused when I recently put the gauge pod back in.  After a few days it then began to throw a code for low circuit on the MAP sensor.  While it was plausible that I had done something during all the electrical work to bork up the sensor wires but I was doubting that.  My money was on the fact that when I replaced all the top end sensors in March of last year while doing a lot of cleanup and de-greasing, I had poorly chosen to use a cheaper unit instead of authentic AC Delco or GM pieces.  And here is something to back up that belief.

First of all I hate how you have to pull the entire intake off just to get at the MAP sensor on these cars.  It really shouldn’t take an hour and a half just to swap a sensor.  After pulling the intake I tried to pop the existing MAP out and while trying to pull it out of the intake it simply came apart.  The top and bottom pieces separated so I was left staring at the guts of the sensor.  Then as I tried to pull the plug out of the intake it just started breaking into pieces.  This is what I was left with.

Broken MAP

Fortunately I had recently picked up a complete motor from a truck that I plan on rebuilding and it still had it’s MAP sensor.  Now the truck sensor is a bit different physically than the car version and in it’s stock form would not fit on the LS6 intake.  On the left is the LS1/LS6 style with the truck version on the right.

MAP Sensor Comparison

So I took some snips and cut off the retaining clips on one side and then filed it down to the sensor body.

Truck MAP Modified

Afterwards it popped right into place.  After getting everything else re-installed I went cruising around to put some miles on it and after about 50 miles in various traffic conditions it gave me not a single problem.  And that is why from this point on I won’t be using anything other than official sensor parts.  On a side note I had my scan tool hooked up while driving around and noticed that my LTFT on both banks are reading around +20 – +22 so the system is just dumping fuel and in all likelihood destroying my O2 sensors.  I’ll have to tend to that in the very near future unless I want to replace even more expensive sensors soon.

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