Need some help please from anyone.1999 Blazer 4.3L auto 4x4 2 door Vin W. If I unplug the MAF while runing it should set a DTC right or wrong. Mine does not what would that mean bad engine computor, wireing problem?

I have a memoscan U381code reader it shows in live data MAF measurements in lb/min. My scanner reads 0.000 engine runing. I changed the MAF still reads 0.000 Any body know if reading 0.000 is same thingas a trouble code. The Map sensor reads around 10.

I bought the scanner on ebay. No tech support for scanner. It is made in China Ufi tech or something I asked them about MAF reading waiting to hear if they answer.

EDIT got a code P0102 MAF or VAF A circut low input. So I guess the computor and wireing are ok. Still do not know why it will not display the lb/min Guess I learned not to buysomething that does not offer tech support.

thanks

 

Sounds like you've got a broken wire in the MAF... Does the engine run any differently when plugged in or unplugged?

 

I knwo this is going off on tangent.... but it's a quick question so I thought I'd ask in the realted forum... Can you take out the honeycomb pattern in front of it and not have anything affected by it or does it it actually do something?

 

Please run a search for 'MAF screen'. It's been discussed before.

 

Did not notice much of a difference pluged or unpluged.

 

If that is a case then there is a problem in the wiring... You either do not have power to the sensor, do not have a good ground, or have a problem with the signal wire to the PCM.

Here is the wiring diagram (click on the thumbnail to view the larger image):


Check for power on the right pin (pink wire) when looking at the connector with the catch up. Check for ground on the center pin (black wire w/ white tracer). You could put a volt meter with the black lead on the center pin and the red lead on the right pin and it should show +12V with the key on, but it's best to check both independant of each other. Then check continuity between the left wire in the connector at the MAF sensor (yellow wire) and cavity 28 on the red plug on the PCM (located on the passenger side attached to the top of the coolant overflow bottle.

If all of these check out, then you may have recieved another faulty MAF sensor, but if any one of these checks does not work out, you have to find where the fault is located...

 

That may be beyond my ability right now but thaks for the info.

 

Really all that is required is a multimeter to make things easiest.

But this could be done with a test light as well, but to test the wire to the PCM, you would need to have both connectors disconnected, run a wire from red plug cavity 28 to either ground or +12V source (battery + terminal), then connect the fixed end of the test light to the opposite source (+12V or ground) and touch the pin in the MAF plug corresponding to the yellow wire (left pin with the latch up).

For the power and ground to the sensor, use the test light with the fixed end opposite what you are trying to probe. So if you are checking the +12v source, put the fixed end to ground. Checking ground, put the fixed end of the test light to +12v source.