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I have a 6.0 from a 2002 denali, swapped into a 1977 camaro with T10 4 speed. when scanning I see my MAP reading is 15.1 lbs 104 KPA. This never changes under any load and my motor seems to flood itself out. when about 2 minutes into a drive, my O2 sensors go off the chart and the motor has no power.
New to the LS world.... Any tips would be appreciated.
Follow the vacuum line from the intake manifold to the map sensor.
This line is the most important line on the car.
Map sensor needs a dedicated vacuum line, NO T's
It should run to a trusted intake manifold source. I usually have a map barb fitting welded on the back of the intake manifold.
You can check the vacuum signal with a gauge, a vacuum gauge or boost gauge (Which reads in Inches of Hg) to make sure the map is seeing vacuum.
In the computer the map sensor signal on a running engine will fluctuate constantly. Don't run the engine until this is solved.
For example mild cammed V8 will pull 15" Hg at idle. That is about 50KPA on the map sensor.
Quote:
Originally Posted by kingtal0n
The motor has the original truck manifold on it and the map sensor is plugged into a pigtail. The only vacuum lines are the brake booster to manifold and PVC valve cover to manifold. I could not find a leak. I also double checked the manifold and found no leaks. In looking at the scanner, it shows vacuum at only 7 to 8 psi.
I did purchase a new map sensor and when I plugged it in, the motor was racing at 2200 rpm and would not settle back down. The strange part was, the kpa never changed. Still maxed at 104.
Okay I am trying to explain the map behavior to you, it should follow intake manifold vacuum.
You see 7 or 8 psi of vacuum that is approx 14 to 16" Hg of vacuum. That would result with a map reading of 40-60KPA, not 100.
If you see vacuum then the map should also see vacuum.
Engine idle is controlled by AIR leaking. So if your engine idles high then it has a vacuum leak. A Throttle body is just a controlled leak.
You should perform a pressure test to find leaks. Here is pressure test video
https://www.youtube.com/watch?v=rYZmZqn3-x0
To be clear you seem to have 2 major issues first,
1. MAP sensor should register engine vacuum (possible bad map, poor map configuration, wrong map wiring, etc..)
2. Engine RPM too high (find all vacuum leaks and fix them)