Crank and Cam relationship on 1997 Exporer with 5.0 V8

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  • tenfooter
    Senior Member
    • Apr 2007
    • 101

    Crank and Cam relationship on 1997 Exporer with 5.0 V8

    I have a 1997 Explorer which I believe to have the wrong cam and crank relationship. I want to know If anyone would have the information to determine where the missing tooth on the crank reluctor is located in degrees before TDC and when the Cam transition should occur in degrees before or after TDC. If you could get or provide a known good pattern I would appreciate it. This vehicle barely starts and if it does will not rev past 580 rpm. I Have a real strong suspicion that this pattern is wrong. Sorry for the small crank signal I was in a hurry taking this snapshot.
    Attached Files
  • wilf
    Junior Member
    • May 2007
    • 6

    #2
    How is this
    Attached Files

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    • tenfooter
      Senior Member
      • Apr 2007
      • 101

      #3
      Thanks!

      I really appreciate your reply. This car has actually had a lost bolt find the balancer at idle and shut the car off. I have checked the balancer/keyway for damage. Here is the proof.....
      Attached Files
      Last edited by tenfooter; 06-14-2007, 07:26 AM. Reason: update

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      • Rick
        Junior Member
        • Nov 2007
        • 11

        #4
        Tenfooter You should be aware that the capture Wilf put up is correct for a 6 cylinder and it is wrong for your 5.0 application. The missing ckp tooth is at 90* btc #1 on 4 cylinders,60*btc #1 on 6 cylinders and 50* btc #1 on 8 cylinders and 10 cylinders. The ten cylinder uses a 40 -1 tooth ckp sensor the others use a 36 -1 tooth ckp sensor. The hall switch cmp sensor should have it's rising edge at 26atdc compression for number one. It's a 50% duty cycle signal and it's falling edge would be at 26atdc #1 exhaust. Be aware that in your case where the cam sensor is installed where the distributor used to be you can install it 180 out or 360 crank degrees out and the computer will not figure it out. It thinks everything is fine and will trigger the injectors on the compression stroke making the engine run bad. So use a sync signal to ensure the rising edge is on #1 compression and not exhaust. The vr type cam sensors have their falling edge cross the 0 voltage point at 22.5 degrees atc #1 compression.

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        • diesel71
          Senior Member
          • Feb 2008
          • 921

          #5
          being i work mostly on diesel"s this is good info.
          i do have one question, is there or is there not a pid reading in data that say's
          sync? i know on the 6.0 diesels there is this pid and if it say"s yes then the cam & crank signals are in sync and working.

          Comment

          • Rick
            Junior Member
            • Nov 2007
            • 11

            #6
            Diesel 71 hello. There is no pid specifically for the cmp sensor to ckp sync unless it is a vct ( variable cam timing) system then there are a few pids relating to the cmp sensor and errors. The cmp signals are different for the vct as well. They will have one more signal than the number of cylinder per bank. So a 4 cyl and an 8 cylinder will have 5 cmp signal for one revolution of the cam. The extra or odd tooth is used to id #1 compression and on a v8 #1s companion on bnk 2 or #6 as the case may be with ford v8s. I would think his should have set set a dtc for p0340 cmp sensor problem. His rising edge appears to be about 25-30 degrees before tdc. They should code if the signal falls outside the pip window. On this dis system the pip signal is internal to the pcm but it's the same as the pip signal from the old distributor systems less the signature pip for #1. you just can't view it on this dis system. The pip signal was a square wave with it's rising edge at 10* btc and it's a 50% duty cycle signal so it's falling edge would be at at 35*atc for an 8 cylinder engine. The pip signal always has it's rising edge at 10* btc and is a 50% duty cycle signal so it's falling edge would be 90* later for a 4 cylinder 60* later for a 6 cylinder and 45* later for an 8 cylinder.
            Note that his cam appeared to be advanced about 50 degrees. The cam advancing it self doesn't happen often so it should be a clue to have a look at the crank sensor for a problem.
            I can't say about the 6.0 diesel but the 7.3 wasn't always right about the cam sensor. Below is a before and after image of a 7.3 in an 02 f-550 that was a no start. The cmp sensor read rpm just fine and the only code in it was a p1219 cid circuit low. This was a new cmp sensor installed at another shop after it quit running and was towed in with a code for the cmp sensor. After the new sensor it was still a no start but no more cmp sensor code.
            The upper image is the no start capture and the lower image is after replacing the new sensor with an oem sensor. The blue trace is the cmp sensor, the red trace is the fdc signal from the pcm to the idm and the green trace is the cid signal from the pcm to the idm. You can see how the sensor is dropping the narrow spoke and randomly some of the other spokes in the upper image but the ecm thinks all is well with it.
            Attached Files
            Last edited by Rick; 04-18-2008, 06:04 PM.

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            • diesel71
              Senior Member
              • Feb 2008
              • 921

              #7
              thanks for the reply rick. yep i know all about the 7.3"s cmp sensors seen that same scenario on a few truck"s. the oem sensors seem to work best.
              on the 6.0"s there is a sync pid that will read yes or no. when ever i get a no start and they happen to run the battery's down,the first thing i look at is this pid to make sure the cmp & ckp are in sync. usually there will be a dtc for one or the other but when they run the battery's down and there are no codes it"s a quick easy confirmation that they are ok.

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