# 1996 Nissan pickup 4x4 idle issue



## 96nissan4x4 (Jul 12, 2016)

Hi have a 96 Nissan pickup 4x4 w/ 109k miles that starts and idles decent when cold and drops to 900 but once it gets warm it starts to drop to 500 and fluctuate between 9 and 500. It will idle fine for a few seconds then fluctuate. Smells like it's running rich to but no engine codes at all.

So far have replaced:
Intake, throttle body, Exhaust, intake gaskets
Maf sensor with oem one
Tps sensor
Cleaned iacv valve 
Water coolant temp sensor
Completely cleaned throttle body and plate
Both o2 sensors replaced oem
PVC valve
Just did full tuneup(cap,rotor,plugs,wires)

Any help in the right direction would be greatly appreciated.

Running out of ideas and really want to fix idle


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## rogoman (Dec 16, 2004)

There may be a 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 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.

Another possibility is dirty or leaking fuel injectors. To test them, unbolt the fuel rail from the intake manifold and pull off the entire assembly. Keep the fuel hoses still connected and don't remove any individual injectors. Also keep the electrical connectors on the injectors. With the assembly now away from the intake, turn the ignition key to the run position WITHOUT STARTING THE ENGINE. Now observe each injector to look for leaks. There should be no drips.

Make sure you have spare insulator rings for the injectors in case some are damaged during rail removal.

It's possible that the injectors are just plain dirty. Run some good injection cleaner, like Techron or Redline SL-1, through the system; Give the cleaner about a week or two to do it's job. There is also a product called "BG products 44K". It is however a very strong cleaner and in some rare cases it has worsened fuel injection operation.


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## 96nissan4x4 (Jul 12, 2016)

Ok greatly appreciate the info, will do in morning and get back with results.


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## 96nissan4x4 (Jul 12, 2016)

Ok so no vacuum leaks was at 20inhg and when revved when upto 22. Also all injectors checked out ok and also tested the ohms of each and all were good. 

Truly stumped on why the idle is fluctuating. Could this be a ecu issue?


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## 96nissan4x4 (Jul 12, 2016)

I noticed its also doing the flucuating while still semi cold to.


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## SPEEDO (Jun 9, 2003)

ok, just throwing some things out there... IACV (air regulator), BPT hose (little frisby by the egr, little hose underneath) if its a V6 the air intake boot, check for cracks


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## 96nissan4x4 (Jul 12, 2016)

Ok checked the bpt and ran a pressure check and no leaks. Its a 4cyl.

Ok what i found is if i put idle at 1250-1300 rpms it no longer fluctuates.

Also when under 1100 or so rpms it doesnt stay in closed loop but at 1250-higher it stays in closed loop.

Would alternator cause lower idle to have issue?


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## 96nissan4x4 (Jul 12, 2016)

So in live data im getting ltft% of 25.0% in closed loop and stft% of 19.5%. If i lower idle to 900 or so it goes into open loop closed loop fault.


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## smj999smj (Jan 1, 2006)

SPEEDO said:


> ok, just throwing some things out there... IACV (air regulator), BPT hose (little frisby by the egr, little hose underneath) if its a V6 the air intake boot, check for cracks


96 and 97 Harbodies as well as the 98 Frontier weren't available with a V6.


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## smj999smj (Jan 1, 2006)

What's the fuel pressure?


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## Spokane95PU (Jan 14, 2017)

Hey 96Nissan4x4, Did you ever resolve your idle issue? What was the problem?


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