There are 4 factors that stop the main, #5 from being open at idle
1:no vacuum at P above (ported vacuum is dead)
2: VSV is closed via ECU command.
3: the main #5 has an internal spring inside, keep it close.\
4: the main #5 valve is not stuck open. its closed. via all the above.
if not idle WILL fail (drop). or stalls.
#5 usually fails every 50k miles, and on most are no longer usable after 150k mlies.
seem some that pass bench tests but stick only hot... can be a real pain that.
on the other side of the coin, getting rid of 51s or passing smog is a much longer story.
stalls or loss of idle controls or way low IDLE:
keep in mind, if #5 is closed, (check it, clean it test it by hand)
you can at any time.
pull hose 16 at line 14
then put a screw in the end of 16
to test idle. issues.
any time.
which proves the EGR main, is not contributory.
it is , i corrected my drawing error, sorry for that,
i added lots of hints to the drawing.
there is one more logic path that stops EGR main from opening.
that is the modulator.
the modulator , in the absence of"bark back pressure waves."
defaults to venting, killing all EGR flow.
so if the bark tube is dead, there can be no EXH EGR flow. 6 different ways.
1:no vacuum at P above (ported vacuum is dead)
2: VSV is closed via ECU command.
3: the main #5 has an internal spring inside, keep it close.\
4: the main #5 valve is not stuck open. its closed. via all the above.
if not idle WILL fail (drop). or stalls.
#5 usually fails every 50k miles, and on most are no longer usable after 150k mlies.
seem some that pass bench tests but stick only hot... can be a real pain that.
on the other side of the coin, getting rid of 51s or passing smog is a much longer story.
stalls or loss of idle controls or way low IDLE:
keep in mind, if #5 is closed, (check it, clean it test it by hand)
you can at any time.
pull hose 16 at line 14
then put a screw in the end of 16
to test idle. issues.
any time.
which proves the EGR main, is not contributory.
it is , i corrected my drawing error, sorry for that,
i added lots of hints to the drawing.
there is one more logic path that stops EGR main from opening.
that is the modulator.
the modulator , in the absence of"bark back pressure waves."
defaults to venting, killing all EGR flow.
so if the bark tube is dead, there can be no EXH EGR flow. 6 different ways.
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