Problem: Fast Idle

[bluecraka]

Hi All,

Long time since I visited, but hoping some of you guys can give some advice. Currently having a problem with NH 91model Pajero the 3.0L V6 fast idle, it is idling at approximately 2000RPM , when I drive the thing there doesn't seem to be loss in power and is smooth when driving but it won't stay at a steady idle under 1000RPM when at rest or no load. If i drive it and pull up, for a few moment the engine revs down and up down and up betwoon appox 1000 to 2000RPM, before settling at 2000RPM.

Have check the air flow sensor, the air temp sensor and the continuity to leads back to the ECU, have removed the ECU and checked over that and there appears to be no leakage from caps or any scorch marks.

Note also before pulling the sensor off and testing, we did have a fault code which appeared to be 35 however looking in the manual there is no such fault code. We than decided to reset the ECU by disconnecting the battery took it for a drive for appoximately 30minutes and check the fault codes again, this time no fault codes.

Any ideas

[corkhead]

i had similiar problem with my NF when i first got it .....

mine turned out to be one of the heat sensors near the thermosat housing (has two facing the radiator) when i took them out one was all corroded.

changed and fixed instantly

[Adomw]

do a search in this forum for "Idle" - you'll find a heap of stuff about the Idle Air Stepper motor about $150AUD, its on the throttle body and is easy to test do they do get stuck or lazy

Also check that no hoses to the intake manifold/ plenum have come off - there's a heap of them - for the brake master cylinder - fuel canister etc

and there's a air idle speed screw in the throttle body - my one was loose as i had to reset it and but a blob of nail polish (red looks best depending on what you're wearing oops forget I said that) in the tread to stop it from winding itself out.

I think that's it

Ado

[bluecraka]

I've taken the ISC stepper motor out and checked the resistance on the winding and all are in spec. The gregory's says you should be able to hear this motor on ignition on, however both myself and a mate cannot, including when placing a screw driver on and to ear. Also states there should be battery voltage when measured across terminal 2 & 5
Therefore went to the control relay remove it and tested this, the gregory's state with jumper leads connect terminal 10 to positive battery terminal and negative to terminal number 8 and should be able to to measure the battery voltage across terminals 4&5. However when doing this was not able to read a voltage. This is with relay connected direct to battery. However can hear the relay click in place when power is applied to terminal 8 & 10. When checking the continuity of terminal according to the gregory's its fine..

I would have thought possibly wiring from control relay to ISC motor causing there to be no power on terminal 2&5 of the ISC wire harness however now that I have removed the control relay and unable to read a voltage it has me wondering whether its the culprit of my problems ?

If it is the control relay any ideas on cost of part?

[-Scott-]

Is there a fuse supplying the control relay?

[bluecraka]

I'll have a look at wiring diagram again to check for fuse but when I tested the relay it was fully disconnected from car, and connected direct to a battery for testing.

What I'm up to is I've pulled the ISC motor and throttle body off the intake inorder to clean the throttle body out with cleaner, done that okay. However the O'ring that sits in between the ISC and the throttle body looks like it has stretched, any ideas on where to get a replacement O'ring?

[bluecraka]

Well managed to get the current o'ring back in to suffice in between ISC and the throttle body. So bolted all back on leaving the wiring harness to the ISC disconnected, (had wound the ISC rotor to full extension prior to putting motor back on the throttle body). Cranked the motor over and whalla back under 1000RPM , turned her off and plugged in the wiring harness to the ISC cranked it over again and whalla still under 1000RPM at idle. Ran out of time to take her for a run will do that hopefull in the morning.

Will let you know the result after taking her for a run.

[bluecraka]

Well so that you know if anyone else is interested or comes across this problem, it appears cleaning the throttle body out with some thottle body clearner has done the trick. Took the girl for a run for appox 45min - 1hr and is operating as normal, ie when at idle she now idles.