Hey CL! Been lurking this forum for a while and hoping for some help from those who may have experienced this issue. Here is some background:

- I picked up a CPO '15 IS250 FSport back in 2016 (used w/ 20K Km/13.6K miles). So far its been a fantastic addition to the family. Right now I've just finished the 4 year bumper-bumper warranty and some issues have popped up (car has 69K km/43K miles now).
- I've recently triggered some CEL codes when driving in manual mode in SPORT. I've triggered a P302 Cyl 2 misfire code that the dealer ended up determining was a bad coil a few days ago.
- Coil was replaced today. After picking up the car (after they closed..of course), I drove it in manual mode (SPORT mode) to see if I could trigger it again. Low and behold P302 AND P306 were triggered.
- I suspect the coil pack isn't the issue now.

I see that the older 2IS models had similar issues due to carbon build up. I believe this was fixed for the 3IS 2.5L engines...I hope.

I'm hoping somebody may have had a similar experience with a successful fix. Right now I was charged a premium to replace a coil pack that was not the issue. Hoping to help narrow down the issues.

Thanks CL!

 

coil is usually the first route in solving the issue. Maybe the spark plugs are on the way out which are replaced at 60k miles. Could be a damaged coil harness which is trigerring multiple cylinder misfires. Is the car stock with original intake still intact? If your still under warranty take it back and have them look into it.
I don't remember the codes i had on my 2006 IS250 that had heavy carbon build up but the most common signs were rough idle at a stop light, sudden loss of power when accelarating .

 

Thanks for the reply! Here's an update:

- Vehicle is 100% stock
- Coil packs are not covered under the standard warranty (4yr) or power train
- Dealer re scanned (no charge) and did not find the P302 that my scanner pulled, but did find the P306. My scanner is a Matco MD1052
- Dealer replacing #6 coil (P306 code) at no charge labor and decided to replace #4 as well at no charge labor
- I'm skeptical that these packs would die at such low mileage and only trigger codes when driving in manual mode (SPORT).

I am doubtful this is the issue but will report back if its fixed. Right now it feels like they are throwing parts at the problem but have been assured that they followed the diagnostic procedure and bench tested the coils to confirm they're bad.

Stay tuned.

 

Update - looks like it was another coil pack that went. Replaced the second pack and third on that bank. No issues to date.

 

Update (again) - P306 has showed up once again. All I did was drive the car at highway speed and it was triggered merging into a lane. Quite an issue when you go into limp mode while other vehicles are coming up behind you.

Coil 6 was replaced from the previous posts. No symptoms from when the pack was replaced until now (just over a month).

Symptoms - loss of power, flashing CE light, transmission downshifting and revving real high, could not manually get it to shift using the paddles. Trans would eventually shift if I let my foot off the gas.

Anybody else getting these symptoms? The infamous carbon build up shouldn’t be prevalent in these new 3IS 250’s?

 

Carbon buildup is a reality no matter what car you drive. Direct-injection engines like the one in your 250 are more vulnerable to the problem than most. If the car was babied before you got it, it very well could have some buildup. From what I understand, Lexus has improved the engine for the 3IS, but I think it's impossible to completely remove the possibility of carbon buildup.

I believe RR Racing had an IS 350 that was babied a bit, and it had carbon build up. It has the dual port- and direct-injection setup, and it was pulling timing like crazy. They had to run some injector cleaner through it and reset the ECU to get it to be behave. Just wanted to give an example, since you know, everyone says "Welp, I have a 350, so carbon build up is not an issue", and lo and behold, it still is.

http://blog.rr-racing.com/news/tag/carbon-buildup/

 

Yeah every car is going to have carbon build up there's no way to completely avoid it, but how much and how bad it gets is something else entirely.

 

If your dealer is replacing coils they are morons and you should take it elsewhere.

I would do a can of bg44k in the fuel system, sea foam in the intake.... then change plugs if they weren’t replaced recently. If that doesn’t help, check your compression.

Rafi

 

What if I wanted to do that on a is350 with only 41k miles on it? Even though spark plugs aren’t due till 60k would u recommend changing them after said procedure?

 

Why do it if you don’t have a problem?

Rafi

 

Thanks for the comments everyone! Today’s update:

”Master Tech” went through the Toyota trouble shooting flow chart. Packs are now “good” and they narrowed it down to plugs.

6 plugs replaced. I’m convinced their tech does not have the skill set to correctly root cause this issue and feel like the plugs may not be the issue. Next item on their list would be injectors but have been told those are working correctly.

I kept the old plugs and they don’t look bad except for one that looks lean. Dealer could not remember what cylinder the lean looking one was removed from.

Anybody here able to point me in the direction of a service manual for the 3IS or a manual from a similar engine set up? I want to bench test the coil packs I kept and see if their tech is just throwing parts at my car or if he’s doing his due diligence like a master tech should have. Is there a resistance value I should be looking for?

 

I don’t drive hard very often so I’m thinking whatever carbon buildup there is could be reduced by A) starting to mash it more and B) doing the things you mentioned.
would it be “bad” to do that to a car not displaying those symptoms?

 

Update:

4th time the car has been in now. Same symptoms as before, P306 tripped with loss of power (limp mode) and engine vibration.

Diagnosis
Compression test done on all cylinders. The bank with cylinders 2/4/6 showed signs of a leak so the dealer removed the intake manifold to inspect. Low and behold signs of carbon build up on the intake valves. Head was pulled this afternoon and I hope to get some status this week. Looks like they're going to send it out to get cleaned and inspected.

100% sounds like the carbon build up issues on the 2IS 4GR-FSE.
https://www.clublexus.com/forums/is-...hreads-89.html

Provided my canadian dealer the TSB since they were not aware of the issues on the 2IS.

Considering getting rid of this IS250 and going with an IS350 instead........

 

How bad was your carbon build up?

Could you share some pictures? Also, driving styles, gas used and other useful details?

Thank you

 

No photos unfortunately. This was dealer diagnosed. Got the car back and no issues yet. We’ll see how this goes.

City/highway driving
premium fuel only (shell)
70000km
mix of spirited and normal driving (sport mode)