07-21-2020, 11:52 PM
now cold RPM, comment.
well if hot fails, Cold can fail too, after all the same wrong air leaks cause both to fail
and cold RPM is not ECU controlled at all there is no ISC servo controls cold started.
the IAC controls cold idle, that and is pure mechanical thermal device, not electric.
the IAC sends in a fixed amount of air say at 50F cold start, so if there are leaks (illegal) then you get IAC + illegal leak flows of air and RPM goes too high.
the IAC is closed hot, above 150f it is 100% closed if not RPM regulation fails.
The ISC will try very hard to close down 100% to hide a bad IAC but will fail. (depends on level of leak that)
a tiny IAC leak can be hidden by the ISC normal regulation and authority, to do so.
The IAC can be defeated 2 ways, to prove it is bad, or 3rd way, just tested in pan of hot water.
way 1, block gasket port to IAC bottom TB
way2, block IAC suck port under air horn cap
way3 test IAC in pan of hot water. 160 to 180f test. I do both.
way4: spare TB. Yah Rightttttttttttttttttt
all 3 ways take spare gaskets. sorry but that is how the cookie crumbles. lacking $1300 spare TB.
well if hot fails, Cold can fail too, after all the same wrong air leaks cause both to fail
and cold RPM is not ECU controlled at all there is no ISC servo controls cold started.
the IAC controls cold idle, that and is pure mechanical thermal device, not electric.
the IAC sends in a fixed amount of air say at 50F cold start, so if there are leaks (illegal) then you get IAC + illegal leak flows of air and RPM goes too high.
the IAC is closed hot, above 150f it is 100% closed if not RPM regulation fails.
The ISC will try very hard to close down 100% to hide a bad IAC but will fail. (depends on level of leak that)
a tiny IAC leak can be hidden by the ISC normal regulation and authority, to do so.
The IAC can be defeated 2 ways, to prove it is bad, or 3rd way, just tested in pan of hot water.
way 1, block gasket port to IAC bottom TB
way2, block IAC suck port under air horn cap
way3 test IAC in pan of hot water. 160 to 180f test. I do both.
way4: spare TB. Yah Rightttttttttttttttttt
all 3 ways take spare gaskets. sorry but that is how the cookie crumbles. lacking $1300 spare TB.
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