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Hello.
My brother has a 2001 Nissan Xterra with a 3.3L V6, 200k miles, 2wd that is causing me a bit of a trouble. Allow me to explain.
It all started over a week ago when I replaced the driver’s side motor mount. After I replaced the mount, I started Helena (name of the Xterra) and was immediately confronted with a very high idle (4000+ RPM). I have 3 error codes, 1 of which is pending: P0325 (knock sensor-PENDING), P0505 (MAF Sensor Malfunction), P0100 (Idle Air System Malfunction)
This is what I have checked so far:
1. MAF sensor (cleaned the old one + put it back on; put a new one on). Did disconnect it to see what would happen, and the car idled from 1000-2000 initially. I then turned it off and put the connector back on the MAF.
2. Idle air control valve (pulled the intake off, tested resistance between the terminals and cleaned the IAC, put new gasket and hoses on the intake and put the intake back on; hooked up a new IAC to it, gave same response as old one)
3. TPS
4. Throttle and cruise control cable
5. Connections (pigtails, etc) within reason (didn’t go all the way down the line to the computer)Please, for the love of God, help me. This has consumed a FULL week and I really need to start working on my other cars.
Edit to add: Car does not have a throttle opener, just the accelerator pedal and cruise control cables.
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I’m assuming you checked all the sensors and harnesses that were near the motor mount you changed. I’m not sure if this helps, but here is a list of the inputs to the idle air system:
Sensor Input
Camshaft position sensor
Mass air flow sensor
Engine coolant temperature sensor
Ignition switch
Throttle position sensor
Park/neutral position (PNP) switch
Air conditioner switch
Power steering oil pressure switch
Battery
Vehicle speed sensor
Ambient air temperature switch
Intake air temperature sensornote this is from the 2003 Frontier FSM, but I don’t think the VG33E has changed much since then.
Are you able to look at live data and see what the desired idle is? Can you look at freeze frame for the P0100 to see what may be out of spec?
Good Luck
Lets start with the simplest …
Was the vehicle running properly prior to swapping the motor mount ?
If so, chances are reasonable the cause of your issue is due to something that was done during the mounts replacement.It was running good enough.
With that said, my brother did mention that the idle was a little high, but that was a minor issue for a while now. That’s why I thought it may have been the IAC or MAF or something that went out by my raising and lowering the engine.
But, yes. It worked.
Also, keep in mind I am fairly new to mechanic work. I’ve only been the “family mechanic” for maybe a month or so. Before, the best I could do was replace an air filter or change the oil.
My first suggestion would be to retrace your steps and see if anything is out of place or possibly damaged or binding.
Check any electrical connections you may have disconnected.Turns out when I was trying to get the top nut off of the motor mount, I remember using a piece of rebar to pry on my ratchet to get more leverage. I pried against the throttle body >.<
Yeah, I know: pretty fking stupid.
I checked it after I did it to make sure I didn't damage it, but I thought the small gap present in the butterfly area was normal ("Well, the car needs a little air to start, right?" So I thought, not realizing that the car doesn't need that big of a gap). I learned my lesson: think things through before using any part of the car as a leverage point.
Anyway, after 2 weeks, I got a new throttle body for ~$30 from a pick-and-pull and now it runs great (except for a small vacuum leak I can hear).
Thanks for the help.
Glad you got it fixed. Don’t beat yourself up too much, I think everyone here has learned a lesson like yours.
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