What are the symptoms of a bad MAP sensor

[GWS]

Lately, my truck stumbles at low rpm/low boost and belches a large plume of black smoke. High boost performance is ok, but generally, more black smoke than usual is produced if the peddle is tromped. The check engine light came on, so I took it to the dealer who discovered a DTC code saying MAP sensor voltage input too low?. Do these symptoms sound consistent with a faulty MAP sensor? Could it be the Power Edge?

 

[DHatfield]

I had that same code on my trucks computer when I had my PE on my truck as well.

 

[GWS]

I checked all the map sensor connections and the power edge harness and everything seems ok. The smoke problem occurs regardless of the edge being turned on or off. My Edge is not supposed to give added fuel at low boost anyway. I d/c'd the VA as well but this did not help the symptoms any. I will change the fuel filter, but since the smoke is black, I don't believe the problem to be a lack of fuel but rather too much fuel at low boost.

I will check the re-0880 k/n filter but it was serviced not too long ago, and I don't think the problem is a lack of air, since my peak boost numbers are very good (30 lbs with moderate acceleration, and 42 lbs with wot). Next I will pull and clean this IAT sensor everyone's been talking about. I will also attempt to clean the map sensor if possible, since DC WILL NOT COVER IT UNDER ENGINE WARRANTY AS THEY SAY IT IS NOT A LISTED PART!

 

[Alan Reagan]

If my logic is working correctly, and it may not be, if the voltage is too low, that makes the engine think you are at a high altitude or that you are not making boost. If you don't have boost it may be trying to fuel to give you boost. The problem is that the fuel entering the system is based on the amount of air you have to burn it so I can't see why the low voltage would give you more smoke. If the voltage was too high, then you should be allowed to get the extra fuel. So to answer your question, I don't think that will cause the smoke, but it would probably cause a decrease in power due to a slight defueling. For reference at sea level the voltage should be 4. 6 volts and at 10,000 feet (if I remember right) it should be around 2. 4-2. 6.

 

[Todd T]

the first thing that should be done is disconnect the PE and clear the codes. then see if the symptoms are still present. then take it from there.



dont just check the connections, weed it out.