Rough/low idle 2008 xB
 

Hi Everyone,

My 08 xB has 90K miles on it roughly and it has started doing this low idling thing where it feels really rough like it is going to die when stopped.
When driving it is fine, it has power and all is well.

Is there an idle adjustment somewhere?

Thanks,

Alan

Hi Alan

Yeah, not too sure about an idle adjustment. I would think the throttle body (rear engine area) would have an adjustment. But, I would imagine its due to an issue & adjusting an idle screw will likely not solve the issue

Ive only got 35K on mine & have not done any engine diagnostic work

Joe

You are probably right. Maybe I should get one of those code retrievers and see if it has any. I've got some fuel system stuff I can run through it, but I don't know if that with help as it seems plenty good when not idling.

Have you ever had the spark plugs changed, if not pull and inspect them. Also you can clean out the throttle body, that helps some times too.

unless you have a check engine light on, you shouldn't see any codes.

Good to know - no check engine light.

Greg - thanks I saw a YouTube video about changing the plugs and that didn't look too bad. I'll try that next and see what that does.

I squirted some Lucas upper cylinder lube in the gas tank a couple of days ago and then drove it once and it wasn't having the problem that time...

What you could do if you're close to changing your oil, is you could do a seafoam clean. 1/3 can into the engine oil, 1/3 into the gas tank, and 1/3 into the intake via the brake booster line. That'll clean out any carbon buildup.

Or ya can give it the ol italian tune up for a few days...

I have a 2012 Scion xB. My check engine light came when it was idling rough then stall. and about 20 or so codes came up. Ive change my I.A.C., MAF. and my upstream O2 sensor.
I have unhooked my battery + and- then left it alone overnight. It still idles REALLY rough (300-400 rpm) there is no check engine light because I reset it when replaced the sensors.

Do you think my TPS is bad?

The low rough idle happens when u disconnect the battery. Did u disconnect the battery recently

My xB was a little rough on start up recently, so I pulled the plugs. The gaps were good still, but the white carbon deposit on the center insulator looked a bit thick.
Got a small brass brush out and cleaned off the deposit and it fired up great after that.
Perhaps the spark was tracking down the carbon to ground???
Could this be related to the low/rough idle???

A tip: I used a deep well socket to loosen the plug, then a length of fuel hose (5/16" I think by 6 inches long) with a 1/2 inch axial cut at one end to remove and replace the plug.
It slips over the insulator and has just enough grip to pull the plug up and out. Handy for those who have a plug wrench where the rubber grommet is worn out or missing.

Change the coolant temp sensor
 

As crazy as it sounds try replacing the engine coolant temp sensor located top of engine to the right (drivers side) of the head when standing in front of the vehicle that sensor is faulty tells the computer to adjust the air fuel mix ratio
depending the engine temperature so you could have multiple codes as a chain reaction to that one problem. It showed up on my Scion a 2008 as a P0117 code. Then after you replace clear the codes and see how it runs.

_____

Thanks Ryan89 - as I remember, and I could be wrong, it seemed like this was a fuel filter or something. Working now.

My only issue at the moment is a lazy starting A/C compressor on my 2008. My 2015 had the same problem, but they replaced the compressor which fixed it. 2008 is not in warranty however. I guess there is some sort of valve that sticks int he compressor if you haven't used it in a day or so. Takes about a mile or two before it will kick in and work fine.