87 F150 MAP sensor diags
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87 F150 MAP sensor diags
Ok..Been going thru the motions testing things...Truck has been running Ok, with somewhat lower mileage and occasional stall when cold...
But, been going thru sensors and testing,.,.No codes, mind you..but still going thru...
What i have noticed on the MAP sensor is the following behavior....
a)VREF is 5V from the ECM KOEO
b)When testing Voltage across Signal return as Haynes says to do, I get 2.5 V, where Haynes says i should get 5 :-X23
c)I add 20lb HG to the sensor, and i get pretty fast bleed off, and no change in voltage (this is when sensor is warm)..Cold sensor gave me 2.5V and dropped to 1V with 20lb, but still bled off presure to 0 within 20 seconds...
How normal is this??..I am a little unsure about replacing, since its a $50 part, and a previous post mentioned that they also saw 2.5V...
There have been lots of posts about using an RPM gauge to test, but haynes mentions that if you get any voltage from the test, then you have the type to be tested with volt meter...
Anyone seen this behavior before?..is it normal??
Thanks all....Ronnie
87 F150 4x2, 302 MFI, AOD, K&N filter
But, been going thru sensors and testing,.,.No codes, mind you..but still going thru...
What i have noticed on the MAP sensor is the following behavior....
a)VREF is 5V from the ECM KOEO
b)When testing Voltage across Signal return as Haynes says to do, I get 2.5 V, where Haynes says i should get 5 :-X23
c)I add 20lb HG to the sensor, and i get pretty fast bleed off, and no change in voltage (this is when sensor is warm)..Cold sensor gave me 2.5V and dropped to 1V with 20lb, but still bled off presure to 0 within 20 seconds...
How normal is this??..I am a little unsure about replacing, since its a $50 part, and a previous post mentioned that they also saw 2.5V...
There have been lots of posts about using an RPM gauge to test, but haynes mentions that if you get any voltage from the test, then you have the type to be tested with volt meter...
Anyone seen this behavior before?..is it normal??
Thanks all....Ronnie
87 F150 4x2, 302 MFI, AOD, K&N filter
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