190k miles advice to keep her going strong
#31
I don't think that's entirely true on these trucks. PCM controls spark advance and retardation but if its not hitting the degree that the computer thinks it's hitting, then the timing would be off.
#32
PCM reads crank position from the crank sensor. Turning the distributor has zero affect on ignition timing. The most you can accomplish there, is turning the distributor so far that the spark can't jump to the correct terminal. (and you may end up firing the wrong cylinder.)
Sensor in the dist only tells the PCM which cylinder should be at firing position. it switches state once every crankshaft revolution. It's only influence is on which injector fires, and when. (fuel sync)
The ONLY way you can alter ignition timing on these trucks is thru programming, or, physically moving the crank position sensor.
Sensor in the dist only tells the PCM which cylinder should be at firing position. it switches state once every crankshaft revolution. It's only influence is on which injector fires, and when. (fuel sync)
The ONLY way you can alter ignition timing on these trucks is thru programming, or, physically moving the crank position sensor.
#33
I'm betting if you threw a scanner on the engine the degrees of advance vs what a timing light with advance would be totally out of sync.
#34
The distributor only makes sure spark goes to the correct cylinder, aside from that, it has zero control over ignition timing.
#36
Cam position only changes state once per crankshaft revolution. (have a look under the cap. It's just a hall effect switch.) It is in one state while 1, 8, 4, and 3 are in the firing line, it is in the opposite state when 6, 5, 7, and 2 are up.) All the cam sensor does, is clue in the PCM as to which injector to fire, on the next crank sensor event. It has absolutely zero affect on when the coil fires. The spark will jump to the nearest terminal, regardless of if it is + or - a few degrees to either side of it.
#37
I just had this same conversation with a mechanic buddy of mine. He is an older guy and hasn't kept up with the times. I still don't think I convinced him that it isn't possible. He says if it has a distributor you can change the time. Some folks never change! How long ago was it that vehicles began being made this way? I'm guessing with the advent of direct fuel injection? or was it OBDII?
#38
I just had this same conversation with a mechanic buddy of mine. He is an older guy and hasn't kept up with the times. I still don't think I convinced him that it isn't possible. He says if it has a distributor you can change the time. Some folks never change! How long ago was it that vehicles began being made this way? I'm guessing with the advent of direct fuel injection? or was it OBDII?
#39
#40