high throttling while sitting idle
#1
10-04-2015, 08:46 AM
high throttling while sitting idle
i look through here for a thread but couldn't find one. Have a 00 dakota that i noticed esp on a cold start siys in a high idle around 1000 rpms and just holds there. i know it usually runs around 500 - 700 rpms roughly. Today and the other day i actually, while on the road, shifted the truck into neutral and throttle did drop into 500 rpms but then when i reved it up the truck shut down but none of the idiot lights came on. all my gauges dropped down, lost power steering, but not brakes, the engine died and was able to start right back up. Are the 2 connected or do i have 2 separate problems. also could this be an electrical issue? i think my alternator is going bad
#3
10-04-2015, 10:19 AM
High idle at cold start is perfectly normal. It should eventually kick down to 600-700 RPM when warm. I had an issue with rough idle and even stalled a few times when coming to a stop.... cleaned the IAC and it worked for a while but came back. Replaced the TPS and it's like a new car now.
#4
10-04-2015, 11:32 AM
Record Breaker
+1 on TPS. You can test it to be sure, turn the ignition key to run but do not start the truck. With the throttle closed probe the center pin on the TPS electrical connector with a volt meter, it should be between .5 and .75 volts. Then open the throttle plate slowly by hand. The voltage at the center wire should increase slowly and steadily as you open the throttle, and should read between 4.5 to a maximum of 5 volts with the throttle held wide open. If the voltage is not similar to the specs or is erratic as you operate the throttle, the TPS needs to be replaced.
You can also remove the IAC and clean it with throttle body cleaner, also clean the IAC orifice on the back of the throttle body. Just clean the black crusty junk off the pintle end of the IAC, do not move the IAC shaft in and out either, that will damage the stepper motor. Handle the IAC gently and do not drop it. Lube the IAC o-ring with a little clean motor oil before you reinstall it. The best and most thorough way to clean the IAC is to remove the throttle body from the manifold first, then take the IAC off the throttle body. It is not hard to remove the throttle body. Unplug the MAP, TPS and IAC, remove the throttle cable, cruise and TV cables and remove the 13mm bolts holding the throttle body in place. Use a new gasket when you reinstall the throttle body. When I clean mine I hold it over an empty oil drain pan and spray it with throttle body cleaner, use a clean shop rag and a q-tip to clean it. Also lube all the pivot points with silicone spray. Use throttle body cleaner, not carb cleaner. There is a difference between them.
You can also use your volt meter to test the battery and alternator. With the engine off you should have 12.5 or 12.6 volts across the battery terminals. Start the truck and the voltage should increase to 13.8 or so to about 14.5. Then turn on the headlights on high beam and the AC with the fan on high. The voltage should drop by 1 or 2 volts but should almost instantly come back up to the high 13 volt to 14 volt range. You can also stop by a parts store and ask them to test the battery and alternator. Most will do it with a basic hand held scanner but it can give you an idea of what is going on with your electrical system. Dakota's are very sensitive to even the slightest low voltage or drop in electrical current or signal from a sensor at the PCM.
Good luck and let us know how it turns out.
Jimmy
You can also remove the IAC and clean it with throttle body cleaner, also clean the IAC orifice on the back of the throttle body. Just clean the black crusty junk off the pintle end of the IAC, do not move the IAC shaft in and out either, that will damage the stepper motor. Handle the IAC gently and do not drop it. Lube the IAC o-ring with a little clean motor oil before you reinstall it. The best and most thorough way to clean the IAC is to remove the throttle body from the manifold first, then take the IAC off the throttle body. It is not hard to remove the throttle body. Unplug the MAP, TPS and IAC, remove the throttle cable, cruise and TV cables and remove the 13mm bolts holding the throttle body in place. Use a new gasket when you reinstall the throttle body. When I clean mine I hold it over an empty oil drain pan and spray it with throttle body cleaner, use a clean shop rag and a q-tip to clean it. Also lube all the pivot points with silicone spray. Use throttle body cleaner, not carb cleaner. There is a difference between them.
You can also use your volt meter to test the battery and alternator. With the engine off you should have 12.5 or 12.6 volts across the battery terminals. Start the truck and the voltage should increase to 13.8 or so to about 14.5. Then turn on the headlights on high beam and the AC with the fan on high. The voltage should drop by 1 or 2 volts but should almost instantly come back up to the high 13 volt to 14 volt range. You can also stop by a parts store and ask them to test the battery and alternator. Most will do it with a basic hand held scanner but it can give you an idea of what is going on with your electrical system. Dakota's are very sensitive to even the slightest low voltage or drop in electrical current or signal from a sensor at the PCM.
Good luck and let us know how it turns out.
Jimmy
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V8Cowboy (11-26-2021)
#5
10-04-2015, 06:04 PM
#7
10-05-2015, 08:53 AM
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#10
10-10-2015, 02:30 PM
well i havent had time to do anything due to working over time and having house projects with a baby on the way, however i noticed that today when i had the truck in cruise control i noticed hesitation and the rpm's were slightly jumping. the best way i can describe it was as if the truck was trying to shut down and kick itself back on. like if i was running out of gas, which im not i just filled it lol. anyways with that would you guys say that this still could be the TPS or IAC or would this be a bigger problem?