I've been having an issue for about year a now where my car hesitates when starting from a stop and then surges up in RPM to where it should be. In the past few months I have replaced the fuel pump, spark plugs, and some vacuum hoses for reasons unrelated to this issue, and the issue is still present. Is there any way for me to test my MAP sensor to see if it is actually bad before I shell out $40+ on a new one?

 

Have you done the obvious and pulled the engine codes to see if anything showing ?

https://www.thirdgen.org/forums/tech...s-dumbies.html


If you have MAP codes present , the problem could be with the wiring / power / grounds ; not just that the MAP unit itself may be faulty
Read
http://www.chevythunder.com/map_code_33.htm
http://www.chevythunder.com/map_code_34.htm

 

To make it simple, a MAP sensor is just a variable resistor.
Max vacuum =1 volts or less, minimum vacuum =5 volts or less,
it changes based on the load.
1 volt lean fuel... 5 volts rich fuel
You can watch it change with a scanner to see if it works proper (look for KPA) 0-100

 

No codes from the car. Apparently the issue isn't bad enough to trigger any.

So at 0 kPa the voltage should be 5V, and at 100kPa the voltage should be 1V?

 

I looked in one of the GM manuals once and it didn't provide any test methods for the MAP, it just suggested replacing it if it was suspect.

If you're able to log ECM data, you can see if the logged MAP values look sensible. Not sure how reliable it is trying to eyeball that, but it's something.

I don't know the voltage scale, but if this is a TPI car, then keep in mind also that the fuel pressure regulator is referenced against the same thing (manifold air pressure). So if you hook up a fuel pressure gauge, and also backprobe the signal voltage on the MAP sensor, you should see them moving in unison.

 

The other way around 100 kpa 5volts (wide open throttle) 0 kpa 1 volt or less (20 in. vacuum)

 

What's 40.00 dollars if you love your car. Everyone loves their car don't they? LOL