Some of you must think that I spend so much time here on Stangnet that I never drive my Mustang or that it never breaks. Not so...
I get in my trusty 5.0 Fox Mustang and it cranks right up... and then it dies... It won't idle of all things. I am in a hurry to get to work so I think that I'll drive to work and fix when I get home in the afternoon. Bad guess; it pops and sputters and keeps dying, so I turn around and just make it back home. No idle, and me the Fix-it Guy for idle problems.
So I borrow the wife's Honda Odyssey and go to work. I put the Mustang out of my mind since I have lots of other things to think about. Get home, rest, eat supper and look at the temp in the garage - it's 90 degrees and not getting cooler. Time to put on shorts and T shirt and go to work.
Just to let you know, I do try to practice what I preach; first step dump the codes.
Get an 11, computer passed its internal self test, then a 31 - EFR voltage below closed limit, then a 63 - TPS voltage below low limit, 18 SPOUT out or wiring fault, 96 Fuel pump power circuit fault.
Code 96 - I know the fuel pump is working OK because the under hood gauge shows 39 PSI with the engine off = probable wiring glitch or dirty connection on this one.
Code 18 - SPOUT or wiring fault - unplug the SPOUT and look at the pins in the connector; they are dirty looking. So I put the SPOUT in and out several times in a effort to clean up the connection and promise myself to check it again after several days of driving.
That leaves codes 31 EGR voltage below closed limit, and 63 TPS voltage below low limit. What do these 2 sensors have in common that would cause them to have low voltage output? And the answer is... 5 volt VREF that the computer provides to give a clean, stable, regulated voltage for these sensors to use. I didn't get a code 22 for the MAP/Baro sensor, so I know that the computer is providing good 5 volt VREF. That leaves either the TPS or the EGR sensors to check. I check the orange/white wire 5 volt VREF on both sensors and find that it isn't there. So I go back to the engine side white 10 pin connector and pop the wire cover off the top the 10 pin connector. Then I poke a straight pin in the orange/white wire and find no 5 volt VREF there either. Bad connection inside the white 10 pin connector, so I separate the 2 parts of the connector and inspect the pins. Nothing unusual catches my eye, so I print out the 10 pin connector diagram
Since I don't have any electrical contact cleaner handy, so it's time to take a small screwdriver and close up #2 pin and the pins on each side of it. Put the 10 pin connector back together and its time to test some more. Go turn the ignition back on and check the TPS & EGR sensors 5 volt VREF and it is good. Turn the ignition switch off, reconnect all the things I disconnected to test them and it is time to see if I did any good.
Crank up the engine and Bingo!!! Perfect idle once again, smooth and steady. Do a cylinder balance test and it comes back with a 90 - that's all cylinders tested good.
The moral of the story is: Test, observe, diagnose and THEN repair. This gives the best results and has the least amount of sweat and scratched up knuckles.
I get in my trusty 5.0 Fox Mustang and it cranks right up... and then it dies... It won't idle of all things. I am in a hurry to get to work so I think that I'll drive to work and fix when I get home in the afternoon. Bad guess; it pops and sputters and keeps dying, so I turn around and just make it back home. No idle, and me the Fix-it Guy for idle problems.
So I borrow the wife's Honda Odyssey and go to work. I put the Mustang out of my mind since I have lots of other things to think about. Get home, rest, eat supper and look at the temp in the garage - it's 90 degrees and not getting cooler. Time to put on shorts and T shirt and go to work.
Just to let you know, I do try to practice what I preach; first step dump the codes.
Get an 11, computer passed its internal self test, then a 31 - EFR voltage below closed limit, then a 63 - TPS voltage below low limit, 18 SPOUT out or wiring fault, 96 Fuel pump power circuit fault.
Code 96 - I know the fuel pump is working OK because the under hood gauge shows 39 PSI with the engine off = probable wiring glitch or dirty connection on this one.
Code 18 - SPOUT or wiring fault - unplug the SPOUT and look at the pins in the connector; they are dirty looking. So I put the SPOUT in and out several times in a effort to clean up the connection and promise myself to check it again after several days of driving.
That leaves codes 31 EGR voltage below closed limit, and 63 TPS voltage below low limit. What do these 2 sensors have in common that would cause them to have low voltage output? And the answer is... 5 volt VREF that the computer provides to give a clean, stable, regulated voltage for these sensors to use. I didn't get a code 22 for the MAP/Baro sensor, so I know that the computer is providing good 5 volt VREF. That leaves either the TPS or the EGR sensors to check. I check the orange/white wire 5 volt VREF on both sensors and find that it isn't there. So I go back to the engine side white 10 pin connector and pop the wire cover off the top the 10 pin connector. Then I poke a straight pin in the orange/white wire and find no 5 volt VREF there either. Bad connection inside the white 10 pin connector, so I separate the 2 parts of the connector and inspect the pins. Nothing unusual catches my eye, so I print out the 10 pin connector diagram
Since I don't have any electrical contact cleaner handy, so it's time to take a small screwdriver and close up #2 pin and the pins on each side of it. Put the 10 pin connector back together and its time to test some more. Go turn the ignition back on and check the TPS & EGR sensors 5 volt VREF and it is good. Turn the ignition switch off, reconnect all the things I disconnected to test them and it is time to see if I did any good.
Crank up the engine and Bingo!!! Perfect idle once again, smooth and steady. Do a cylinder balance test and it comes back with a 90 - that's all cylinders tested good.
The moral of the story is: Test, observe, diagnose and THEN repair. This gives the best results and has the least amount of sweat and scratched up knuckles.