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 "
OBD2 Monitors Completion
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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 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. -
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.
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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
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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-!! LOLComment
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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-!! LOLComment
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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
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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 worksLast edited by Witsend; 05-30-2015, 06:54 AM.Comment
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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 $Comment
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