My 2012 Fit Sport has developed a bit of a rough idle when first starting out when it is below about 40 degrees outside. I know this isn't cold by any stretch of the imagination for vast swaths of the Fit-driving world, but it doesn't seem to happen when it's warmer out.

Anyway-it seems to work itself out after about 1/2 a mile or so of driving.

I accidentally left one interior passenger/map light on overnight about 2 months ago, and the rough idle has started since then. I usually start the car with the lights on but no A/C or rear defroster.

Does this sound familiar to anyone?

TIA.

 

How many miles does it have on it?

 

About 20K.

Forgot to add that it only seems to do this when it sits overnight. No other problems that I am aware of, and it's had regular oil changes. Maintenance Minder says oil life is at 40%.

 

The mileage is low and everything should still be in great shape.

Even if its when this started, I cant see the relationship between the light being left on and the start of the problem.

Spark plugs and coils should still be like new too but could cause a slight misfire if they are failing early.

A vacuum leak sometimes can be felt on cold start ups and then seal itself up once warmed up but it usually sets a lean code.

The on board computer should identify a misfire or a lean condition and put on the check engine light.

Sometimes people experience real world problems with their vehicles that dont set codes until they get worse. It can be a source of frustration for a customer when they bring a vehicle to the shop. Their frustration and perception cause them to feel as if our technicians should be able to plug our magic diagnostic computer in or just snap our fingers and have the answer.

I belive you have something going on but you may need to tough it out until it can be detected by the on board computer. BTW, im not suggesting you are one of those customers. Im saying I feel for you but there may not be data to look at yet.

If I had your vehicle at our shop, I would keep it outside over night in the cold and hook up a scanner to it in the morning. I would monitor the data stream before the first start up and look for a sensor that is out of normal ranges, could cause your problem and not set a code.

Ex. A coolant sensor might read the coolant temperature at 75 deg F while its actually 32 deg F outside. The on board computer wouldnt even detect the problem because the reading is still in normal acceptable ranges but not accurate. That kind of failure wouldnt allow the on board computer to add more fuel for the warm up since it thinks the engine temperature is wamer than it really is.

So, depending on the shop you take it to, they my not even do that. I have worked with life long journeyman techs that would think nothing of starting up a cold start problem vehicle before a cold scan. Then letit warm a little and thenplug in a scanner. Thats kinda like missing the boat or the window of opportunity to scan for an anomaly.

Find a shop that either will diagnose it like that or will do it because you ask them too. Most important is that when you discuss that method of detecting the problem, they understand what you are asking and agree its a good start.

Good luck with this one!

 

Thanks for the help and advice, 2010. I think I'll wait it out. No other problems to speak of. Love the car otherwise.