Primera 1.6i idle speed

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Thu 23 Dec 2004 14:10
Primera 1.6i idle speed - Kostic
Hi,

Just though I'd gather opinions on the following.
The car idles at around 700rpm, which seems about right. The only thing is, this is with a heater fan on. Fan speed doesn't matter, just whether it is on or off. Switch it off, idle rpm drops to may be around 400 or so, difficult to tell as there are no marks on the tacho between 0 and 1000.

In both cases it idles perfectly stable, never stalled. ECU also seems to do its job correctly by slightly upping rpms if a/c is turned on.

I wonder if this was a mistake made by a dealer who did the last service (that was before I bought the car), i.e. he adjusted idle speed with the fan on instead of off ? Or is it a normal behaviour for this car (very much doubt it).

Thanks

Kostic
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Thu 23 Dec 2004 14:33
Primera 1.6i idle speed - Number_Cruncher
Assuming this is the 1997 Primera with excess oil in the sump :-), I would expect that the idle speed is controlled entirely by the engine management system, and probably cannot be adjusted easily.

At the risk of my sounding like a stuck record, beware of trusting the devices that clutter dashboards which some people mistakenly call instruments - IMHO and experience, they can sometimes be quite misleading. For example, I don't think your car would be running at all smoothly at 400 rpm, and a stall would be quite likely, i.e., in reality, it will be running faster than 400rpm.

In the days when you had to set the idle speed on car engines, a dedicated bit of test equipment was always used to read engine speed, rather than the dashboard mounted, customer pleasing, cheap gimmick.

As the car hasn't had a stalling problem, and you don't seem to have a problem with the engine racing, then I suspect everything is probably OK.

number_cruncher



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Thu 23 Dec 2004 14:46
Primera 1.6i idle speed - Kostic
Thanks Number Cruncher

That's right, it's the car with overfilled sump. Actually not any more, I've managed to syphon a bit out, so it is now only around 1mm above :-) I might be able to get big medical syringes very cheaply, so I could build myself oil/whatever other fluid suction/injecting devices for any future maintenance work.

As for so-called instruments on the dash, I absolutely agree. It is probably more than 400rpm but still feels a bit low.

However, there IS an idle adjuster on IAC valve. It regulates how much air bypasses throttle butterfly.

As the car runs very well I'll leave it till the next full service at which point I'll mention it to the mechanic. The question is actually aimed at improving my knowledge base :-)

Kostic
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