Rough idle 2002 2.5 please help

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 or you can get it done at most auto parts stores for free. 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.

It's most likely running in "fail safe" mode where the ECU has detected a failed condition and has restricted the rpm to around 2500 so an ECU code readout is essential.

The only codes I was getting is po507 and the normal maf codes when I un plug it to try to get it to stay running .

The vast majority of bad idles with P0507's are cured by performing a Closed Throttle Position Learn (CTPL) and an Idle Air Volume Learn (IAVL). IAVL calibrates the MAF, which is probably most of your problem.

I tried the relearn and itll do the first 2 steps but it wont run long enough to warm up for the last step

Briaan said:

The only codes I was getting is po507 and the normal maf codes when I un plug it to try to get it to stay running .

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Before running an IAVL, check the following conditions that could possibly cause the P0507:
● Intake system vacuum leak. 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 around 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.
● Problem in the PCV system; entails replacing the PCV valve or bad connecting hoses.
● As a last resort, the electric throttle control actuator may be bad which entails replacing the throttle body.

If you're unable to perform an IAVL, have a Nissan dealer perform the function.

The maf is brand new along with the throttle body and the cam /crank sensor and I've already checked for a vacuum leak.nothing seems out of the ordinary there and same with the pcv.

The only thing I was not able to do is the last step of the relearn because it will not stay running long enough to warm up the engine.

Update. I cog the relearn successfully done and it didnt change anything I'm still getting black smoke from the exhaust and limp mode.

You may have a bad upper O2 sensor or one or more fuel injectors are leaking causing a rich mixture.

One thing I have noticed that isnt right is at idle the load_pct says 100%

Briaan said:

One thing I have noticed that isnt right is at idle the load_pct says 100%

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When you're referring to a 100% value, what diagnostic tool are you using?

Autel obd 2 scanner looking at live data

Load_pct is engine load by percentage. Gives you an indicator how hard the engine is working at a given time. Not real helpful on it's own but gives you more context when looking for an issue. It may be related to the P0507 code that indicates a problem with the electric throttle control actuator that's on the throttle body; that's just a guess.

When I bought the car I was told the throttle body was bad so I got one from the junkyard and have the same problem but I was told you cant manually turn the butterfly valve or it breaks them and I accidentally did on install.

did you check the fuel trim?

Yea they looked about right

Briaan said:

When I bought the car I was told the throttle body was bad so I got one from the junkyard and have the same problem but I was told you cant manually turn the butterfly valve or it breaks them and I accidentally did on install.

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The throttle valve opening/closing is controlled by the ECU. If you broke the throttle valve flapper, the entire throttle valve needs to be replaced and then perform a Closed Throttle Position Learn (CTPL) and an Idle Air Volume Learn (IAVL). IAVL calibrates the MAF.

did you check the fuel trim?