# 2000 maxima idling at 1500 rpms



## aplagens05 (Jan 31, 2017)

Hello everyone. I am new to Nissans and this forum. I bought a used Maxima GLE V6 automatic with 133k on it this past summer. Known issues when I purchased:

Oil sending unit
Valve gaskets
Plenum gasket

Since I have a decent amount of mechanical capacity, this wasn't all that overwhelming. BUT..in the process of replacing and cleaning things it became apparent that the previous owners did zero maintenance on this car. The plenum, airbox and throttle body had oil running out of them when I removed them. I cleaned, replaced, hoses etc and got it back together. Here are two issues that need to be addressed:
Plenum bolts: 2 are broken (not by me) need to pull them out and get replacements. TB bolt for the bracket that attaches to the plenum well, one is stripped and again, needing replacement. Could these issues be causing the high RPM, or could it be the IACV? Its old, and I cleaned some oil residue off it when cleaning everything else. Also, is there a place to purchase the bolts, or just go to a hardware store and match them as best as possible?

Thanks,

Adam


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## rogoman (Dec 16, 2004)

By removing the throttle body, the learned idle speed was disrupted. At this point you need to perform the "“Idle Air Volume Learning” procedure which is an operation to learn the idle air volume that keeps the engine idle within a specific rpm range. It must be performed under any of the following conditions:
- Each time IACV-AAC valve, throttle body or ECM is replaced.
- Idle speed or ignition timing is out of spec.

Before performing “Idle Air Volume Learning”, perform the following which is called “PRE-CONDITIONING” making sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment:
- Battery voltage: More than 12.9V (At idle)
- Engine coolant temperature: 70 - 99°C (158 - 210°F)
- Park/neutral position (PNP) switch: ON
- Electric load switch: OFF (Air conditioner, headlamp, rear window defogger)

Here's the procedure as specified in the FSM:
- Turn ignition switch “ON” and wait at least 1 second.
- Turn ignition switch “OFF” and wait at least 10 seconds.
- Start engine and warm it up to normal operating temperature.
- Check that all items listed under the topic “PRE-CONDITIONING” (previously mentioned) are in good order.
- Turn ignition switch “OFF” and wait at least 10 seconds.
- Start the engine and let it idle for at least 30 seconds.
- Disconnect throttle position sensor harness connector (brown), then reconnect it within 5 seconds.
- Wait 20 seconds.
- Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.

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You might be able to purchase the throttle body bolts from a Nissan dealer, junk yard, hardware store. Bring along one of your good bolts to match. Remember the bolts are metric and the thread pitch must be correct.


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## aplagens05 (Jan 31, 2017)

Rogoman:

Thank you. I did this the past weekend five or six times, eve drove the car to ensure it wasnt a stuck throttle. I was able t get it down to about 1000 rms, but it wouldnt go any lower. The only time I got it to 700rpms was after driving around for ten minutes. The car immediately stalled and when I started it back up it went back to idling at 1200 rpms. I am thinking it need a new tps....


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## aplagens05 (Jan 31, 2017)

So i have now replaced the tps, iacv, all vacuum hoses and it it seemingly getti g worse. I now having a surging throttle and it lags when accerating from 1st to 2nd gear. I am unfer the assumption i have a bad throttle body a well as a bad maf or both. I am really beginning to hate this effort to fix an oil leak.


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## rogoman (Dec 16, 2004)

aplagens05 said:


> Plenum bolts: 2 are broken (not by me) need to pull them out and get replacements. TB bolt for the bracket that attaches to the plenum well, one is stripped and again, needing replacement. Could these issues be causing the high RPM, or could it be the IACV? Its old, and I cleaned some oil residue off it when cleaning everything else. Also, is there a place to purchase the bolts, or just go to a hardware store and match them as best as possible?


To begin with, you need to replace the broken plenum bolts; by being broken, there could be a major vacuum leak possibly causing your problems.

If the same problems persist, then one of the first things to do is perform an ECU code readout with a portable scan tool to see if any fault codes are set. The tool can be purchased at most auto parts stores. Some of the conditions you're describing can be caused by a marginal crankshaft position sensor or a camshaft position sensor. If you're buying one or both of them, buy only OEM units from a new car dealer. Don't buy aftermarket types; they've been known to fail in a short time; some are even DOA.

At this point you'll have to determine if there's an ignition or fuel delivery problem:

* How long have you had the old spark plugs? If they are very old, then it's time for a set of new ones.

* Testing fuel delivery:
Tee-in a temporary fuel pressure gauge at the input to the fuel tube. The readings at idle should be as follows:
- with vacuum hose connected to the fuel pressure regulator: 34 psi
- with vacuum hose disconnected from the fuel pressure regulator: 43 psi

* There may be a major intake system vacuum leak:
To check the intake system for a vacuum leak, use a vacuum gauge for good accuracy; most auto parts stores sell vacuum gauges. attach the vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps. 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The vacuum gauge makes for a very good diagnostic tool. Here are some vacuum gauge readings and their indications:

Low & steady: Late ign timing/valve timing, low compression

Very low: Vacuum leak

High & steady: Early ignition timing

Gradual drop in reading from idle to higher RPMs: Excessive back pressure in exhaust system

Intermittent fluctuation at idle: Ignition miss, sticking valve

Needle fluctuates as engine speed increases: Ignition miss, blown head gasket, leaking valve or weak valve spring


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