Question about Nissan Pulsar

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High idle speed- Nissan N16 Pulsar/ Almera

My 2001 N16 1.8 litre Nissan started idling high a few days ago. I have checked the throttle body, throttle position sensor, throttle closed switch, and vacuum hoses for leaks. I have found no problem.
There is no engine check light, nor any fault codes when placed into diagnostic mode.
I stongly suspect the idle air valve to be sticking, as when the throttle is opened then returned to idle, the revs. drop back low temporarily, then rise again to around 1400 RPM. When driving (auto trans) the idle in drive is pulled down to around 900 RPM, but driving at light throttle around 60 KPH with the engine not fully warm, I can feel a surge in the speed, as though the IAC valve is "hunting".
I have reset the memory of the throttle position sensor, and reset the IAC's memory, all to no avail.
I'm wondering if anyone recognises this fault, and can put a finger on what its cause is? I could be way off the mark!
Thanks for any input, in advance..

Posted by Ray Murphy on

  • 2 more comments 
  • Ray Murphy May 30, 2009

    Thanks, Hotchevy1965. I have already inspected the throttle body, and it shows NO deposits around the throttle valve. It is returning fully to the factory fixed stop. However if I do go ahead and remove the IAC for inspection, I will need to unbolt the throttle body to access it. Then I can inspect it fully.

  • Ray Murphy Jul 25, 2009

    Yes, I have found my problem. I did suspect the idle air valve, and it turned out to be right.
    I was a bit worried about tackling it, but eventually decided to carefully try. I had to remove the tube connecting between the air filter and throttle body to gain access to the 2 screws that hold the motor of the valve to the body (it is mounted under the throttle body). I didn't know what to expect when I loosened the screws, but to my joy the motor lifts off the body no problem at all! The electrical plug can be released by pressing the tab just above the motor socket, and pulling out. A test with an ohmmeter on the motor showed a short circuit on one of the 4 motor windings. There is no way into the motor, so replacement is the only option, which means buying the complete valve.
    There are 6 contacts in the motor. From the centre contact each side to the in- line ones should show a resistance of abt. 22- 23 ohms. Mine showed 0 ohms on 1 reading. There should also be no connection anywhere between any of the pins on one side and those on the other side.
    I searced for a best price for the valve. I thought I found it, but when it arrived it was not the valve it was represented to be, so it went back and I received a refund. I am now waiting for the correct one, which I should receive next week... at a cheaper price again, even! Until I receive it, I cannot tell if the bad stepper motor has wrecked the driver in the ECU, that is a very real possibility! I have already enquired re a reworked ECU if I should need it.
    So, the valve IS my problem. Yet to be determined is whether the ECU was damaged.
    If you find the motor on yours is not faulty as mine was, you can plug the plug back into it, and switching the ignition ON and OFF, it should extend and retract. If it does, it is probably NOT your problem. There is a fuse and a relay in the circuit, but if functioning, they are probably OK also. Their location I have tried to find, going by the manual, and they APPEAR to be placed somewhere near the blower motor. Like I say, the manual is hard to follow!
    DO check for vacuum hose leaks that may be bypassing air into the intake manifold, check the throttle valve is returning fully to the stop, and the switch showing fully closed should be ON. The throttle position sensor should show a smooth resistance change as the threottle is opened, and the wide open throttle switch should close when the throttle is abt 3/4 open. Manually cleaning carbon buildup behind the throttle butterfly may resolve any failure to return to closed. Use rag and carburettor cleaner spray. An old toothbrush can be handy.
    Have you found the downloadable factory workshop manual? It has been of great assistance, but is incredibly complicated to follow. It is for the European Almera, but most things are identical. I originally downloaded it when I had an aircon problem,there were some differences there, but I got the general idea and was able to rectify the problem at no cost other than time. It would have been very costly to replace the entire control unit.
    The manual describes the many resetting procedures related to idle speed, throttle pos. sensor, throttle closed switch,throttle open switch, etc.
    It is the ONLY manual available online (probably an error on someone's part), and workshop manuals cost an arm and a leg!
    Please contact again if I can help further.

  • Ray Murphy Aug 17, 2009

    Thank you to all who contributed comments. For YusefHQ in particular, had it not been for you, I would not have had a look behind the idle stepper motor and found coolant there. I removed the throttle body, and replaced the valve body as well. It was not corroded, but the stupid little neoprene gasket had hardened, and was weeping internally under pressure.
    Again, thanks to all, the problem is fixed. I fitted the new IAC valve, and had the ECU repaired. The idle is back to normal after a short "learning" period.

  • etturbo May 11, 2010

    Hi there. I have exactly the same issue with my N16 Pulsar. Did you manage to resolve it and if so can you help me with the solution? Please and thanks



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Battery not charging well when airconditioner on ( also engine speed not increase when air conditioner on )

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Hi 9 times out of ten the reason why it revs high is because the throttle body has coolant leaking into it and it shorts out the ECU. Just open your bonnet and smell the ECU as its only 2 X 10mm bolts and it pulls out of the firewall. Once it is out of the firewall the burnt electrical smell is verrrrrrrrrry obvious. Grab a second hand ECU from the wreckers ( about 100 Gonzallars ) or 3 slabs of VB and go to a nissan dealer and chuck in the new one in their car park then get one of the goons in the workshop to come out and re-program the keys for you and once the ECU is replaced the car wont start until the keys are re-programmed ( Cost about 50 Gonzallars ) or a slab and a half of VB.. Ohh and while ur at the wreckers get a second hand throttle body with no signs of rusty coolant on the butterfly. Cheers

Posted on Aug 04, 2009



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How to remove front door panel on nissan almera

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Clean throttle body with throttle body cleaner.and a old tooth remove carbon build up around throttle blades.besure to remove all electrical parts and plastic and rubber parts before using cleaner.also put a new throttle body gasket back on it. if cleaning dont help.your idle speed control could be the problem.

Posted on May 30, 2009

  • Jonah Oneal May 30, 2009

    yes i remove it and clean it.also check throttle body gasket for deterioration and cracks.check acceleration cable make sure its not binding.if it still idle high after cleaning .idle speed control is the problem..


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47fb9be.gif ------------------------------------------------------
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