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Idle is up to shit! HELP

HeathGTST

By HeathGTST,
in General Maintenance

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HeathGTST Community Regular

HeathGTST

Posted
Posted

Fellas,

Yesterday was quite hot in melbourne and my engine temp reached 86c which is warmish but the car still ran fine... Today when i went to drive my car the idle is very irratic. when the engine is at operating tempreture the engines idle goes from around 900-1400rpm by itself... Constantly goes up and down. I have checked most of the electrical connections and most of my hose connections and yet and still have no cure....

Any help would be much appreciated

i have a 96 mdl r33 turbo manual with a Power FC computer

Cheers

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rutelz Apprentice

rutelz

Posted
Posted

Hey mate,

Not sure whether i completely understand your problem, but it sounds like a similar problem I had... I suggest you check the harness running in2 the ECU, because that was my problem...

The RPM signal was cut, and re-soldered but a very average effort so when it got warm the wire's would expand then when it cooled it would only contact every so often so it would be unstable.

The wire colour is yellow with a blue strip running through it...

Hope this helps but not too sure because I'm not sure whether the harness was changed with the Apexi FC...

Goodluck mate,

Let me know how you go!

HeathGTST Community Regular

HeathGTST

Posted
  • Author
Posted

the problem seems to be related to engine temp... car idles fast when its cold because its on the cold start procedure, when the engine temp gets to 60c the engine note changes a little and as soon as it hits 68c the idle goes all funny.... from 1200-1600rpm.... up and down up and down constantly.... When I turn the car off and restart it straight away at operating tempreture the engine sits on 2000rpm for around 5 seconds and the drops to 1200rpm and revs up to 1600rpm up and down.... Its really giving me the sits...

It didnt do it yesterday but today i did.... Very very strange

RB30-POWER Mentor

RB30-POWER

Posted
Posted

Make sure that you have a fully functioning genuine Nissan Thermostat.

Rated at 76.5degC (stamped on it) $30 from Nissan if thats the problem.

The thermostat is designed to commence opening at 76.5degC and be fully open at approx 90degC.

So yeah, the temp should be within this mark when at operating temperature.

Also with age the Clutch Fan can be engadged all the time, and not allowing the motor to warm up properly.

The clutch centre is viscous type, and should only tighten up when its warm.

And the last thing, make sure the guage is right that you have the temp reading from.

Does it use an independant sensor or is it piggybacked to the factory sensor?

If its piggybacked you can get wrong readings.

R31 POWER Mentor

R31 POWER

Posted
Posted
I would consider 86-92degC normal operating temp for these motors.

86 cruising

92 idle with air-con on + hot day.

If its way lower than that, you are going to get bad economy and accelerated engine wear.

Is that for a RB25det only? because my R32 RB20det sits on 78degC for normal driving and the highest ever temp was 86degC in stinking hot heat with a full car load.

RB30-POWER Mentor

RB30-POWER

Posted
Posted

Thats a general rule of thumb for most motors.

78degC sounds preety fine to me.

I mean if it were lower than the thermastat temperature then it would be a problem.

i.e If you said it was running at 50degC all the time, then there would be a problem.

  • 3 weeks later...
NismoR34 Grand Master

NismoR34

Posted
Posted
Try cleaning the AAC valve. Check the TPS throttle-closed position.

sorry to dig up the thread again but I have been having issues with idle lately also.

Each time I disengage a gear and return to neutral, ie when stopping my revs seem to jump up a couple of hundred rpm. I have pulled apart and cleaned out the AAC Valve numerous times in the last 12 months so it must be something else, any ideas?

Where should the TPS position be when closed? Is there a general rule like TDC or something?

Thanks

Dale

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