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General Forums => The Mess Hall => Topic started by: robertsiii on January 04, 2010, 08:57:23 PM
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made a 3ft. deep water crossing :stupid: over the holidays engine sputtered and had alot of steam come from under the hood. engine never died. now engine cranks and idles fine @ 900 ,Then when i start driving my idle wont go under 1500 . what ever rpm i rev it up to it stays at. i can push the full throttle over ride and rpms drop back to 900. is it tps or iac ? ive disconnected the neg . cable to reset didnt help any ideas. did get my mark viii elec. fan install completed also .heres a pic.
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I'll take a stab at it and guess TPS (Throttle Positioning Sensor). Just a guess. Any codes coming up?
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IAC valve causes this as well.
Dave
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keep in mind this is tbi... iic tbi doesn't have IAC valve it just has the stepper motor that adjusted the throttle position at idle (ISA).
to test the tps use the fallowing procedure from FSM:
Throttle Position Sensor (TPS) Test
Turn ignition on. Check voltage at terminal connector
without disconnecting from TPS. Terminal "A" (M/T), or terminal "B"
(A/T ) is output voltage, which should be 4.6-4.7 volts at wide open
throttle (M/T), or .2 volt at closed throttle (A/T). Terminal "B"
(M/T), or terminal "A" (A/T) is sensor ground. Terminal "C" (M/T), or
terminal "D" (A/T) is input voltage, which is about 5 volts.
may also want to check out the closed throttle switch (which i haven't seen in any diagrams or looked for on my jeep but there is a test procedure for it)...(edit: from further reading sounds like the closed throttle switch is part of the AIS motor http://jeepgarage.free.fr/OWN/fuel%20injection%20system%20tbi.pdf)
Closed Throttle (Idle) Switch Test
NOTE: ALL testing of idle switch must be done with ISA motor
plunger in fully extended position. If switch cannot be
tested without extending plunger, it is possible that ISA
motor has failed. See IDLE SPEED ACTUATOR MOTOR ADJUSTMENT.
1) Turn ignition on. Check idle switch voltage at diagnostic
connector D2, between terminals No. 13 and 7. See Fig. 4. At closed
throttle, voltage should be near zero volts. When switch is off
closed throttle position, voltage reading should be greater than 2
volts.
2) If voltage is always zero, test for short to ground in
harness or switch. Also check for open circuit between switch and
terminal No. 25 of ECU connector. If reading is always greater than 2
volts, check for open circuit in wiring harness between switch
connector and ECU. Also check for open between ground and switch
connector. Replace or repair wiring harness as necessary.
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Great Info, ill do some testing and try to firure what went bad. tx
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Oops misread the year, Guess we can eliminate the IAC! 8)
Dave
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incase you where wondering, for the closed throttle switch test it says "NOTE: ALL testing of idle switch must be done with ISA motor
plunger in fully extended position." if the motor is shut off correctly the computer fully extends the ASI motor plunger after the motor turns off and before the computer fully powers down. so you basically just have to turn on the ignition and the plunger should already be fully extended (ive read this in the fsm somewhere and don't know how common (or uncommon) of knowledge it is.).
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tps tested bad, replaced with mopar part . good to go. thanks for the help guys :clap: