My car keeps throwin out a code 33 almost every other day, and when it does, the car refuses to stay started. After about 4 times of startin her up, she finally stays started, but the SES light comes on. But for the most part, it runs fine. I looked up the code and it said the MAP sensor may be faulty. What exactly does this sensor do? How easy is it to replace? Is it as simple as removing the old, installing the new, and firing the car up? I really don't want to have to take the car somewhere and get raped if I don't have to

 

anyone??

 

TTT

i am very interested in this sensor's functions as well, as another member stated if its bad, you way loos both HP and MPG.....?

 

MAP - Manifold Absolute Pressure - Sensor

It determines the density of the air entering the engine to calculate the air/fuel mixture based on fuel tables programmed into the ecm.
I believe the ecm also takes into consideration readings from other sensors as well as the MAP before making this calculation.
If you have a TPI engine, it's located on the plenum towards the back on the passenger side.
It's about a $50-60 part and easy to replace. I think it is a testable part as well.

 

As previously mentioned, the MAP sensor reads the pressure in the intake manifold. It doesn't measure the density entering the engine, thats more what the MAF (mass airflow sensor) does. The pcm uses the MAP for fuel needs in addition to the TPS and CTS. It is essentially a vacuum gauge for the pcm. You can easily test it with a DVOM. When disconnected, measure the harness connector, key on engine off. One wire should have around 5v and another should have continuity to ground. The other wire is the feedback to the pcm, or signal wire. Typically the outer wires are the 5v (reference) and ground and the center is signal to the pcm. Plug the sensor in and apply a vacuum to the sensor while monitoring the signal wire and ground wire by back probing your DVOM leads into each ckt. With no vacuum applied you should read higher vt, probably around 4.5v. As you apply vacuum to the sensor, the vt should decrease. Watch your vacuum gauge and make sure the reading stays steady and does not fluctuate. If the sensor will not hold a vacuum, it needs to be replaced. Hope this helps.

 

where exactly is this sensor located on an LT1, maybe a pic would be very helpful, by the term "apply vaccum" do u mean me, or with some kind of a machine, becuase i dont have anything that will hold a steady vaccum that i know of?

 

if its an lt1 you might want to try the lt1 board? just a thought

 

well ****...i found this post on a search, and didnt realize it searched outside of lt1 tech...oh well peace out