A place for more technical discussions. Please make sure you post in the correct section on the site, this way it keeps the site tidy AND ensures you get a more relevant answer.
On really cold mornings my Jimny idles at around 1800-2000rpm when it's first started. It gradually settles back to normal once the engine warms up but it's quite annoying as I've got a low speed crawl along a bumpy farm track before I reach a road which means a lot of clutch slipping in 1st. Is this normal?!
My intake air temperature sensor appears to be reading correctly, the coolant temperature sensor is fine, the only odd thing I can see on my fault code reader is that my throttle only opens to a maximum of 72% even when the engine is hot - could a slow/sticky throttle body be causing it? It honestly drives fine and doesn't appear to be down on power at all.
The only other things I can think of are the water pump/alternator/power steering tensioner - one of them has a slight whine but it's so minor I haven't bothered to investigate or start changing parts. Not really keen on taking the radiator out and taking the belts off outside in winter...
Cold idle is directly proportional to coolant temperature but 1800-2000rpm is higher than it should be. Have you got a thermostat fitted? no thermo or a bad one will mean that the engine takes longer to warm up. What do your fuel trims look like? maybe you have a small vacuum leak.
I've got a thermostat fitted, it warms up quick enough once on the road and once it's warm it idles fine, it's only in really cold temperatures that it initially shoots up to high RPM's.
The vacuum system appears to be fine (well to the 4wd system at least) as I went over that with a fine toothcomb a couple of weeks ago when I had a hub sticking on.
What should normal readings be for the fuel trims? Could it even be the wrong mix of coolant causing it to freeze up a bit?
Ours gets up there too but only for a couple of seconds it then settles to about 1400 and then normal as it warms up.
Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
Bellerophon (2024 grello van daily
ADOS Attention Deficit Ooooh Shiny!
Just got around to checking the live data, stupidly lent my code reader to a friend for a couple of weeks. The fuel trims are both around 0 at cold, and during a 10-15 minute run the short term trim never exceeded ±3 and the long term was at -3, neither of which is too bad according to the service manual.
The 2nd lambda sensor confused me slightly as it stuck at a solid 1.275v until the engine was hot but I'm guessing this is because of the heater in the sensor? The sensor in the manifold was fluctuating quite a bit even from cold. It's not really a big problem but it's an annoying little niggle and it's beyond my knowledge!
