Hello,
I have a 2009 IS250 AWD. I bought it in 2010. The last 2 months the check engine light has been coming on intermittently. When the light was solid, I was not overly concerned. When it started flickering, I became quite concerned. I have a trusted and reputable mechanic who diagnosed it as a cylinder misfire. Fast forward, the mass air flow was fixed, there was a carbon build up so the cylinders and manifold were cleaned (thankfully, no damage to the pistons). I was told this had a 90% chance of fiixing the issue. Two weeks later, the light flashed, I had it towed to the mechanic, where it now sits, and after running the diagnostics, they cannot figure out what the problem is. The cylinder misfired but they cannot confirm why. The light has not flashed while they have test drove it.

They are perplexed, I guess a diagnostic test does not always point to a clear issue but instead can pull up many possible issues, all of which need to be further assessed.

They suggested I take it home, don't take long trips, and see if the light comes back on....if it does, to bring it back to the shop. When I asked if driving it without the light on could do damage, they responded no. When I asked if the light comes on, would it be safe to drive it for 15 - 20 minutes to bring it to the garage I was told it would be okay.

I've spent $2000 so far, on what that did need to be done, but am not feeling too secure in having a car where I'm constantly having to look to see if the light is on...and to be limited to how far I can drive.

Has anyone experienced this or have any ideas? There is no warranty on it and I'm not sure if taking it to a dealer would bring me any closer to finding out what the problem is....

All responses are welcome!

Denise

 

While you're here looking for input we rely on you and to a lesser extent what "they" tell you.

Your best bet is to collect your own data and this can be done for pretty cheap.
In short you use an app on your phone and OBDII device that plugs into your car. Now you see what is happening first hand and can share unadulterated information to solve this mystery.

Some of the basic apps are free while others like Torque Pro for Android OS are $10. The bluetooth or wifi OBDII Elm327 is like maybe $30 and BAM you are gathering facts!
Sound doable!?
That said it likely has P030X code for a cylinder misfire. If the work you had done cleaning the top end is holding up well it could be something like a failed COP. i.e. ignition coil. Or Coil Over Plug. Your car has 6 of them.

Let us know.

 

The news was not good. They found that under correct conditions (accelerating uphill, then idling) they could duplicate the cylinder 5 misfire. it's an intermittent misfire, not something that’s happening all the time. They eliminated as causes the spark plug, ignition coil, ignition coil wiring and fuel injector wiring.

They tested the running compression in that cylinder during test drives, and found no abnormal pressure changes. They tested the mechanical components but they can’t confirm that it is not a mechanical issue, however there have been fuel injectors in other makes & models where, with the gas direct injection systems, the metal and/or electronics in the fuel injectors can become deteriorated by the carbon build up (which I had). They said it is possible that due to the GDI service they did during my last visit, some particles are clogging the injector, which would also change the spray pattern.
would be the next step in correcting the check engine light. The part may have to come from Toronto, which would be 2-3 days. Total including parts, labour & tax would be $1706.47.

They gave me 3 options.

1. Do nothing, drive the car as is. This means that eventually the misfire will get worse, which means more hydrocarbons flowing down to the catalytic converter, causing the catalytic converter to fail.
2. Add fuel injector cleaner / gas conditioner to my gas tank and drive around until I've gone through a full tank. This may be enough to clear the injector if it’s clogged.
3. Replace the fuel injector. (this was very expensive and considering the value of the car, I'm not about to shell out that kind of money in the hopes it fixes the problem.

I went with #2, drove about 5 miles and the check engine light started to flicker. I was not on an incline and had just slightly started to accelerate. I pulled over and restarted and the light was off and stayed off the rest of my drive. Who is to say how long it will stay that way though.

I'm going to car shop over the weekend and trade it in. I did not know how about the perils of a GDI engine and the need to have it regularly serviced...and there is no mention of this in my service manual...but maybe in 2009 no one had realized the impact it could have over time....knowing what I know now, I could have likely saved myself the experience and expense had I been aware of the need for GDI servicing. I look after my car in all aspects. Lesson learned...and not one I'll repeat.