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Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 16759
Experience:  15 years GM master tech
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Have a 4.3l s10 blazer 2000. Have a friend do a motor swap

Customer Question

Have a 4.3l s10 blazer 2000. Have a friend do a motor swap .... For some reason the distributor had to be removed. The maf sensor was disconnected while putting dizzy in... Blazer runs as is... But when I go to install and hookup maf it stumbles backfires
and dies.... I had two mafs tried both same result.... Guy said we'll both could be bad ... So bought new one same outcome stumbles and dies... Throws maf code ... So question when he installed dizzy without maf did he basically over compensate for fuel, so
when maf was installed telling it to send correct fuel to air ratio it causes the motor to die?
Submitted: 1 year ago.
Category: Chevy
Expert:  Gary replied 1 year ago.

i am sorry for the long wait

with the MAF unplugged and a meter set to DC volts with the key ON red meter lead into the pink wire terminal and the black meter lead into the black/white wire terminal in the connector what does the meter read ?

Customer: replied 1 year ago.
Not at vehicle...... I'm at work. I will test tomorrow as I work nights. So from that we find if correct voltage is going to maf? I don't understand. Everything ran great before motor swap... I'll get you readings tomorrow.... But question when you pull dizzy and replace dizzy does all sensors including maf have to be connected? Friend says no that it can only be 180 out.... Runs fine without maf idles high but from what I've read with maf disconnected it throws system into default and uses tps to compensate for maf not being there .... Now I worked on a 01 Silverado that had ignition problems that gave dizzy symptoms that when I went to install all sensors had to be in place... So can you get a 4.3 dizzy in the correct slot for timing without maf?
Expert:  Gary replied 1 year ago.

most are disconnected to move the wiring harness out of the way and the MAF is unplugged and removed with the air hose to the throttle body to access the distributor

you are looking for 12 volts at the PINK terminal with the key ON and most important the black/white a GOOD ground

my concern is the black/white will not be a good ground and the ground for that black/white wire is on the back of the drivers side cylinder head which is a common ground to break or leave loose or forget to put back on during an engine swap

you can get the distributor in correctly without the MAF as these distributors are dropped in on TDC and aligned that way

there is no timing to set once dropped in correctly

Customer: replied 1 year ago.
Ok I'll check tomorrow I'll get back with you
Expert:  Gary replied 1 year ago.

sounds good

Customer: replied 1 year ago.
Guy just sent me a message saying he has checked those wires and is getting correct voltage
Customer: replied 1 year ago.
11.5 v to pink
Customer: replied 1 year ago.
5 to ground
Expert:  Gary replied 1 year ago.

and that ground at the back of the drivers head is clean and tight ?

if your sure that ground is good key ON engine OFF with the MAF plugged in what does the computer show the MAF reading ?

what codes is it setting ?

Customer: replied 1 year ago.
Got a cheap code reader it's maf code
Expert:  Gary replied 1 year ago.

ok we need to know the code number it is setting and we need to see what the MAF is reading in the computers live data list

Customer: replied 1 year ago.
Expert:  Gary replied 1 year ago.

can you barrow or rent a scan tool to see what the MAF is reading in the computer ?

this hear needs to be followed

The Mass Air Flow (MAF) sensor is an air flow meter. The control module supplies the MAF sensor a signal circuit. An ignition positive voltage circuit and a ground circuit are supplied to the MAF sensor by independent circuits. The MAF sensor heats a wire element, or grid, within the MAF sensor in order to maintain a calculated temperature. As inlet air flows across and cools the grid, the MAF sensor increases current flow to the grid in order to maintain the constant grid temperature. The MAF sensor converts the grid current flow into a frequency signal. The control module converts the MAF signal frequency into a grams per second value. During low air flow rates, such as at engine idle, the MAF sensor produces a low frequency signal. During high air flow rates, such as at wide open throttle-road load, the MAF sensor increases the frequency signal. The control module monitors the MAF sensor signal frequency in order to calculate the flow and mass of the air entering the engine.

Expert:  Gary replied 1 year ago.

how are you making out ?