Hi,

I left my 2011 IS250 sitting for almost a month (28 days). Hooked up the battery back on, turned car on and got check engine and traction light on at the same time. Ran scanner. It came up with P0300 (random/multiple cylinder misfire detected), P0303, P0304, P0305, which means cylinders 3, 4, and 5 are misfiring. Haven’t driven it anywhere, but it idles low and slight shaking is felt. Also, exhaust smells unusually rich, like raw gasoline. The car ran perfectly fine a month ago when I drove it last, and has been absolutely bulletproof with no problems since new from 2011. It’s got 116k miles now.

For what it’s worth, I had disconnected the battery last month before I left town, so maybe computer reset itself??? Also, the weather was very humid with rain downpours when I started car (thinking maybe air fuel mixture is affected due to humidity and computer getting reset?).

Hope you can shed some light on this!! Much appreciated!!!

 

I would drive it around a bit to see if it helps. Is this the first time that you let it sit?

 

Hey, thanks for the reply.

I’ve let it sit in the past for various durations —1 to 4 weeks, and one time for several months! This never happened. I’m totally at a loss, specially that it was running perfectly fine before my trip last month.
As for driving it around, I thought doing that could ruin the catalytic converter or even engine components (?)

 

Have you tried running a fuel system cleaner through? Could be sediment from the stagnant fuel clogging the injectors.

 

The better way of leaving a car un-driven for a lengthy period of time is to connect a battery tender. A $35 investment, well worth it. Keeps everything intact. Hope a lesson was learned.

 

Possible that a rodent found its way under the hood to make a new home in your wiring harness?

 

Appreciate all the replies. So here’s what happened today. I disconnected the battery and reconnected it again. Started the car, and it ran a little rough like yesterday (low idle, slight shaking). But check engine and traction lights didn’t come on today. I started to gently drive it and within about 5-10 minutes, the car was running perfectly like it always did before all this happened. I drove it to my mechanic and he gave it a couple of stomps on the gas, and based on the way it sounded, he said there was no misfire at all. He said that I could just drive it and it should be fine. I came home and just for kicks, hooked up the scanner again, this time it only read a P0306 code, meaning a cylinder number 6 misfire (yesterday’s cylinder 3,4,5 misfires are gone now). Anyways, looks like it’s ok for now. Not sure what to make of the P0306 code, but no check engine light anymore and car runs perfect like before. Would you still check cylinder 6 or just drive it?

Thanks

 

My brother ran into the same problem with his wife's 07 IS250. He ended up clearing the codes and changing about three fuses in three separate fuse boxes. Not sure where he got the information for trouble shooting the problem but he said that the problem was caused by a weak battery. Hope this helps.

 

Things that sit can have visitors who wreak havoc. Rodents can get busy and chew threw things you'd never imagine. Did you look under the engine cover? Although likely not the case here as most of it recovered on its own but I'd still want to look and see.

If it were mine I'd pull and inspect all the plugs, boots, and coils. Maybe swap #6 and #1. Of course that doesn't rule out a fuel issue.

As for your concern about the cats, yes. Valid. Although for it to run at all I'd guess that all those cylinders that threw codes were not down all at once or would not have kept running which leads me to think moisture / fuel related. JM2C

 

Have your mechanic load test your battery and alternator. Also check the ground wires if they're in good shape and not corroded.

 

Sounds like carbon buildup on intake valves to me.