My '92 Lumina 3.1 with 163K miles has an intermittant "Service Engine Soon" light that comes on and off every few minutes while driving. The codes come up MAP sensor and knock sensor...what gives?
Before I start replacing expensive sensors, I'd like tp know why my Lumina idiot light comes on and after a few minutes turns off while driving. It feels like for the few minutes it is on the engine does run rougher but then goes back to normal when the light goes off.
Also, the engine drips oil and leaves stains everywhere I park it...is there any effective aftermarket stuff I can add to the motot oil to at least slow down the drips? I thiink it's the rear main seal that's worn.
Ideally you should locate the source of the drip. If you have a leaky gasket somewhere then you should remove it, clean the surface, verify that the metal has not been scored or warped, place a new gasket and sealant, and torque to specifications. If the leak is around the valve covers or the oil pan then the repair is fairly easy. If the leak is around the heads or manifold then the work is a bit more tedious and more gaskets are needed. You can easily test a knock sensor using an ohm meter. You should verify that the vacuum line on the MAP does not have a pin hole or leak anywhere. You can test the MAP with an ohm meter as well. If the vacuum line is in question then you can rent a small pump to apply pressure at the vacuum hose connection for testing purposes.
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