OBD2 Monitors Completion

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  • Witsend
    Banned
    • Nov 2012
    • 2942

    OBD2 Monitors Completion

    Will road testing while monitoring evap related Pids before the monitor is completed while road testing certain vehicles in any way, delay,defer , or prevent the PCM from following through with completing the damned Dirty Deed of completing an EVAP monitor if it knows it's being watched on a scanner . You know the old saying "The Watch Pot never boils "
  • Crusty
    Senior Member
    • Dec 2007
    • 2450

    #2
    Originally posted by Witsend
    Will road testing while monitoring evap related Pids before the monitor is completed while road testing certain vehicles in any way, delay,defer , or prevent the PCM from following through with completing the damned Dirty Deed of completing an EVAP monitor if it knows it's being watched on a scanner . You know the old saying "The Watch Pot never boils "
    It depends on how the scanner has to communicate with the engine control module.

    It would be better if we knew what year/make/model/engine/transmission, etc. you were working on.

    Most of the time monitoring datastream hasn't inhibited any that I've been testing but, yes, it is possible.

    Comment

    • Witsend
      Banned
      • Nov 2012
      • 2942

      #3
      Monitor Completion (2001 Honda Civic EX 1.7 VTEC Sedan

      It depends on how the scanner has to communicate with the engine control module.

      It would be better if we knew what year/make/model/engine/transmission, etc. you were working on.

      Most of the time monitoring datastream hasn't inhibited any that I've been testing but, yes, it is possible.
      Reply With Quote
      return of P1457 EVAP canister leak code pending after 2nd road test with new OE Canister shut valve installed. Very weak change in FTP road testing so the return of code P1457 pending is no surprise. All 3 solenoids work when commanded on by scan tool. Vacuum holds between canister purge valve and hose that goes to canister. Un-energized , the Bypass solenoid holds vacuum and when activated with scan tool (DS 708) it bleeds the vacuum. Couldn't see jack sh@t leaking with the smoke from my $20 Craigslist Halloween Fog machine . Already has a new gas cap, and no obvious damage to the charcoal canister, even after removing and replacing the extremely rusted CVS (Shut solenoid)screws.Most of the pinpoint tests are done by a hand vacuum pump and I didn't have 2 vacuum tees of the proper size to run the hoses all together to isolate the canister to vacuum leak check it per step , so I just slammed the close solenoid. I fought the Law, and Murphy's Law Won.

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      • ericsautomotive
        Member
        • Mar 2014
        • 66

        #4
        Try throwing a few test at the FTP sensor. I've had a couple of them trick me in the past.....
        Don't guess! Test !!

        Comment

        • Witsend
          Banned
          • Nov 2012
          • 2942

          #5
          Try throwing a few test at the FTP sensor. I've had a couple of them trick me in the past.....
          Thanks, good idea, just that FTP is displayed in psi on DS 708, so I'm not sure how negative psi translates to in-hg or vacuum.
          Last edited by Witsend; 05-30-2015, 06:41 AM.

          Comment

          • Crusty
            Senior Member
            • Dec 2007
            • 2450

            #6
            Originally posted by Witsend
            Thanks, good idea, just that FTP is displayed in psi , so I'm not sure how negative psi translates to in-hg or vacuum
            Not being familiar with that system, it's possible that the system operational characteristics may actually present a positive pressure on the system under some circumstances and look for a pressure decay (as compared to a vacuum decay)-??

            Regardless, a little pressure on the system (1 or 1.5 psi-??) and a squirt bottle mixed with dish soap MIGHT show something much like checking a tire for a slow leak-??

            I've found a few small leaks that way. Not enough that would show with a smoke machine. Is the system designed to catch a 0.20 or a 0.40 leak-??

            At least it'll get a wash behind the ears-!! LOL

            Comment

            • Witsend
              Banned
              • Nov 2012
              • 2942

              #7
              Regardless, a little pressure on the system (1 or 1.5 psi-??) and a squirt bottle mixed with dish soap MIGHT show something much like checking a tire for a slow leak-??

              I've found a few small leaks that way. Not enough that would show with a smoke machine. Is the system designed to catch a 0.20 or a 0.40 leak-??

              At least it'll get a wash behind the ears-!! LOL
              I isolated the canister and it would not hold vacuum , so I disconnected the hose to the vacuum pump and sprayed the canister down with water and using my mouth blew into the hose to pressurize the canister and pinched off hose and was able to hear some bubbling for a second , repeated a few times and saw bubbles around the new screws that fasten the the new canister close valve to the canister. The honda parts guy gave me a couple new screws to replaced the rotted out originals that were slightly longer, and after I chased the threads of the inserts the new screws went all the way in just fine, but I probably perforated the canister shell with the pointed tip of the 5mm tap .DUH

              Comment

              • Crusty
                Senior Member
                • Dec 2007
                • 2450

                #8
                Or the original rusty screws did. I'm surprised the inserts even stayed in place.

                "Bubbles. Bubbles"
                (Finding Nemo)...LOL

                Comment

                • Witsend
                  Banned
                  • Nov 2012
                  • 2942

                  #9
                  One of the canister inserts did twist out with the rotted screw. I was able to reinstall it after I put the CVS with the head of rotted screw in a vise , heated the insert and unscrewed the insert. I just tapped it back into place with super glue, ground the slightly protruding end of insert flush and chased the threads of the insert with a tap. Never thought it would leak. I wonder if I had rtv'd it ...?

                  I'm replacing canister now like I should have done at same time LOL. Funny thing When I was monitoring Pids I saw the canister purge duty cycle being commanded, but never saw the Bypass solenoid or the Canister vent solenoids didn't appear to be commanded on , so I don't know how it would be able to generate a significant measureable negative pressure reading on the FTP sensor with that . Maybe the CVS was being turned on but every time I glanced road testing, I didn't see either on accept purge solonoid.

                  Well no communication with customer to authorize replacing the canister so I spooged rtv around the screw holes, road tested a couple times, p1457 was not pending and all the monitors were complete except the Evap monitor so ran it through the test lane for a pass , so no worries for another couple years for emission test but want to complete the monitor to be sure .
                  Last edited by Witsend; 05-30-2015, 06:47 AM.

                  Comment

                  • Witsend
                    Banned
                    • Nov 2012
                    • 2942

                    #10
                    Honda Civic Evap

                    Normal data pid list my MT 2500 displayed FTP in both in/hg and in volts. My DS FTP PID only shows PSI , WTF
                    DS had some fancy 15 minute long automated Honda 8 step EVap test that said was completed. I waited for awhile for results to appear whether the tests passed or failed, no test results popped up, so I clicked ok and it brought me back to the initial menu where I started at . GRRRRRRR Re run again and gave result as a possible failure.
                    Pulled hose from canister to tank, put a longer hose on and with mouth blew into hose into gas tank and pinched off hose and put an old school vacuum / mechanical fuel pump pressure gauge on end of hose and released pinch off pliers and gauge held slightly over 1psi of pressure without drop for quite awhile, so the tank and filler tube holds pressure fine
                    Road testing and monitoring FTP sensor now with my MT2500, the FTP sensor showed about 5 in hg and FTP voltage just under 3 volts.
                    With hoses unplugged from FTP , FTP reads from .3 - .8 in hg and about 2.5 V open to atmoshere. Unplugging the FTP electrical connector the MT2500 shows open circuit as 24in hg and 4.96 V. I plugged FTP electrical connector back in and apply 5 in hg vacuum to one port and MT2500 reads 23in hg, I then put 5 in hg to the other port and FTP reads -23 in hg on the MT2500. WTF! I price out new FTP sensor at over $150 and the vacuum bypass solenoid new is around $100 , so i go to the boneyard and find an 02 and pull the FTP, vacuum bypass solenoid, and grab a LF seat belt end release pretensioner for the SRS light and spend about 40 minutes and $25. Plug in the used FTP I sourced and scanner still reads 23inhg with 5in hg applied. Glad I didn't buy a new one. Put it back together and drove it twice , evap monitor still not done, no pending codes yet . Morning drive in the works
                    Last edited by Witsend; 05-30-2015, 06:54 AM.

                    Comment

                    • Witsend
                      Banned
                      • Nov 2012
                      • 2942

                      #11
                      01 honda Civic p1457

                      I ran it through test lane for a pass Took it for a long roadtest this morning P1457 is pending again. Guess the DS 708 don't always lie .I don't believe anything is leaking anywhere, but When 5 in/hg of vacuum is applied to the FTP sensor the FTP pid on scanner shows 23in/hg ,WTF. Tried another FTP sensor pulled off an 02 and reads the same. Figure I have a wiring issue between the FTP and the PCM. I did cut off the connector and pigtail of the FTP sensor and bypass solonoid, if the customer wants me to pursue the problem, but as long as the car has the pass sheet from the test lane, I don't think he'll spend more $
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