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I have 2001 nissan altima auto,4 cyl ,85k and the idle is at 1400-1300 rpm during startup, it goes down to 1100-1200 rpm after warmup,,normally it should be in 800-750 rpm,, i cleaned the idle air control valve and adjust the idle screw and also i replaced PVC valve but no changes,,,any suggestion is greatly appreciated,thanks
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When the EGR is stuck open, it will lead to a vacuum leak which in turn causes inefficient combustion, hesitation, rough idling and even stalling. The reason for this is that the car cannot combust on the carbon dioxide emitted from the tailpipe. An open EGR valve causes exhaust emissions to flood the combustion chamber, hence preventing it from functioning as it should. To check for a stuck open EGR valve, idle a parked car with the brake on and have someone examine the plunger shaft to see if it is stick open.
When it is stuck closed, this causes nitrogen oxide emissions to rise and the car might start to knock. A sharp knock occurs when the fuel in the combustion chamber ignites before the explosion in the cylinder reaches it. This leads to a disruption in engine timing. When this happens, warm up your engine and rev it, then check if the EGR valve will move.
At this point … I’m thinking ..
Have you check the coolant in the radiator?
Do you have good heat in the car?
I’m asking, perhaps you may have air in the system.
Giving a false reading to the temp sensor
Or perhaps a faulty coolant temp sensor.My other thought may be something with the idle air control
It may need to relearn or be replaced (and relearn)
I found the procedure…
It is similar to what is done with the 3.3L V6…PRE-CONDITIONING
Before performing “Idle Air Volume Learning”, make 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.
I Battery voltage: More than 12.9V (At idle)
I Engine coolant temperature: 70 – 99°C (158 – 210°F)
I PNP switch: ON(Vehicle In Neutral)
I Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting
switch to the 1st position to light only small lamps.
I Cooling fan motor: Not operating
I Steering wheel: Neutral (Straight-ahead position)
I Vehicle speed: Stopped
I Transmission: Warmed-up
For A/T models with CONSULT-II, drive vehicle until “FLUID TEMP SE” in “DATA MONITOR” mode of “A/T” system indicates less than 0.9V.
For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.Accelerator Pedal Release Position Learning
Operation Procedure1. Make sure that the accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.Throttle Valve Closed Position Learning
Operation Procedures1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch to “ON”.
3. Turn ignition switch to “OFF” wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.Idle Air Volume Learning (Throttle Position Learning)
[color=#ff0000]This sequence is very easy not to get correct
It is better to count the time accurately with a clock.
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1. Perform “Accelerator Pedal Released Position Learning”.
2. Perform “Throttle Valve Closed Position Learning”.
3. Start engine and warm it up to normal operating temperature.
4. Turn ignition switch “OFF” and wait at least 10 seconds.
5. Confirm that the accelerator pedal is fully released, then turn ignition switch “ON” and wait 3 seconds.
6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.
7a. Fully depress the accelerator pedal (HARD)
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the Check Engine Light (CEL) stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure the idle speed and ignition timing are within the specifications.Heat is good , no air in the cooling system cuz i open the bleeder when i change the coolant a while back.
About the coolant temp sensor,the radiator fan comes on and off when it reach normal temp.
What do you mean by egr stuck open position? Is it like the same position when an engine is off /depress inward diaphragm ?
Can you also explain to me how is the vaccum routine starts and end according to the diagram,in order word who gets the suction and goes where? TyAnd which of the hose or hoses i can verify if theres a vaccum suction in the vaccum routing diagram
In the diagram …The only suction vaccum is the hose thats coming from the intake manifold connected to egr solenoid valve’s lower port, and nothing else according in diagram.
and also theres no changes in idle speed when i disconnect hoses from egr valve, erg-bpt valve,You can test the EGR operation by hooking a hand operated vacuum pump to it and see if it functions.
You may need to check all the components of the EGR to see if they function.
I don’t have that set up on my engine, so its specific operation is not clear to me.
But considering the engine is running smooth, kinda doubt it is your issue.
But it doesn’t hurt to check it.egr works fine, the relearn procedure didn’t do anything,i guessed its not applicable to Altima,but I do have this pdf file(8gb) about 2001 Altima engine control system and its contain idle adjustment but I don’t understand it, maybe if I upload here you or someone can explain better,thanks
Ok from what I read in this..
You would start on page EC38
Following the instruction where the diagnostic tool is X out.
[b]What I see on Page EC40 appears may assist you.
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I am assuming you’ve checked the timing and it is set correctly.Still original timing position ,i never touch it since i bought this car brand new , even the distributor same position,the only thing i change is the distributor cap and rotor a yr ago.
Isnt to check the timing the rpm has to be 700 in park or neutral? I cant get into that range
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