# 1999 frontier 2.4L surge at idle



## squarpeg (Jul 19, 2019)

engine surges constantly at idle or low speeds. I do not have a tac but maybe below 2k rpm will constantly surge with no load on engine.

Note that if it is in gear and has a load on engine of any kind, like you let it crawl at idle up an incline, no surge runs fine. Runs fine at highway speed.

Please see video turn sound up.

Ok looks like I can not post a video because this is my first post. You should ne able to figure this out just get rid of the space between //you

https:// youtu.be/cqr9OACoF50


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## rogoman (Dec 16, 2004)

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. Post the actual codes here on the forum so that we may be able to help you further. If there is one or more fault codes set, they can help point to the malfunction. If you have a copy of the FSM for your vehicle, the code readout procedure is described there along with a listing of codes. You can download a copy of the FSM from this web site: https://ownersmanuals2.com/. The section EC.PDF is the one you need to read.

Here's several things that could cause your engine surging problem:
* - Bad fuel pump or fuel pressure regulator. Tee-in a temporary fuel pressure gauge at the output side of the fuel filter. 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
* - Major vacuum leak in the intake system. To check the intake system for a vacuum leak, attach a 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. 
* - Bad Idle Air Control Valve-Auxiliary Air Control (IACV-AAC).


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## smj999smj (Jan 1, 2006)

Whenever you get surging at idle, it is typically due to a lean condition, therefore check potential areas for leaks, i.e. intake manifold gaskets, vacuum hoses, splits in rubber air intake ducts, etc., as well as for low fuel pressure.


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