First let me start by saying I've seen the threads about stalling at stoplights.. My problem seems to be different.

I'm having a continued problem with my 2007 IS250 AWD misfiring.

First time was at 10k miles, then at 12k miles, then 20k, now again at 38k.

The Misfires don't always trip the check engine light. It's been tripped 4 times but has been logged in the computer several times. My local dealer can't quite seem to get it figured out. The Dealer couldn't get the vehicle to replicate the problem at 10k and 12k.

Twice it has stranded me on the freeway. The vehicle starts shaking violently. All the check engine lights come on, then the vehicle looses power. Roadside tows it in and the dealer usually keeps it for a week or two at a time.

The last time it happened at 20k miles an engineer was sent out to look at the car. The report I was given says "Faulty machining of Exhaust valves causing check engine light to be on, replaced exhaust valves with updated valves. Lapped valves and replaced gaskets. Resealed timing cover and both oil pans."

Ive had a feeling the vehicle was still misfiring but not tripping the check engine light. Well apparently I was right. It happened again yesterday. vehicle started shaking violently and lost all power while driving down the freeway. I shut it down, start it back up and it drives fine. Had it towed in to the dealer.

After talking with them today the only thing they seem to be doing to it is the carbon build up bulletin that came out a few days ago. I have a hard time that this would cause the vehicle to misfire and loose power while driving down the freeway at 80mph. If it was a carbon issue, it seems a bit premature that it would have had these issues at 10k miles as well. This would also suggest that I'd have to have the buildup taken care of every 15k miles. no thanks.

This car has me feeling defeated. Has anyone had anything similar? Any ideas? I'm afraid they're just going to do this carbon buildup bulletin and give me my car back until the next time this happens.

The service guys even suggested I get rid of the car and talk to Lexus about buying it back from me. Has anyone does this?

Thanks Guys!

 

Hi Crystal and welcome to the Forum.

I agree with you that it doesnt sound like carbon especially if it restarts and continues fine..., sounds computer/sensor failure related. Scary that your IS is failing you on the freeway !!!

There are some knowledgeable people on this forum and they should help !!

 

One of the other members was having issues with misfiring. Hopefully someone that's experienced this can help ya out.

 

The only thing I've found online are two consumer complaints here: http://www.arfc.org/complaints/2007/...250/?q=misfire

These describe what's happened to my vehicle. I'm just at a loss.

 

Can't believe no one has come forward to answer this yet lol. Where is that dam guy that had the issue.

 

expierences and problems about carbon build up here>>>>>>>https://www.clublexus.com/forums/is-...d-threads.html

 

Thanks but from everything that I have researched, this is not a carbon build up issue. Any carbon buildup was just taken care of 18k miles ago when the exhaust valves were replaced.

I've found a few consumer complaints where vehicles misfire while driving down the freeway and dealers have addressed them a number of different ways. No one seems to be satisfied.

One person had engine coils replaced, valve springs and carbon buildup clean up and the problem happened again 5 months later.

Another was told they had a failed fuel rail pressure censor. Part was replaced and stalled again.

Another person had the exhaust replaced.


I'm feeling very defeated by the car as this has happened to me 4 times already and my factory warranty is up in a month and a half. I had no intention of getting another car but now I'm forced to get rid of this one as it's just not wise to keep it.

 

My car was having issues with misfires, they ended up replacing the coil packs under warranty, but charged me for replacing the spark plugs. I was at my wits ends with the dealership, cause it was my 4th time there to finally show them there was a problem with the car. The check engine light would go on, but they said it wasn't recording any data, or there was no history of the check engine light being on, so when I finally got the car to misfire again and had the check engine light flashing, I drove it straight to the dealership (I thought I was gonna blow the car up), and made them bring a tech over to show them the light was on and for them to scan it. Car would start to misfire and pretty much fall on its face, however mine occurred usually after I tried giving it gas from a stop, not while I was already in motion. I haven't had a problem since them (knock on wood), but good luck, hopefully you can get it figured out.

 

Weird that yours didnt record the misfire. Everytime mine does it, it records it. I just came from a meeting with the service manager, shop manager and service advisor. After reviewing all of my records it always records the misfire as a random misfire except this time it was on #6. It's always been above 65mph when it misfires. Go figure.

 

have you called the corporate to find a solution?

 

Yes I've contacted corporate. A rep is coming to look at the car and review everything tomorrow.

 

I feel for you.

I don't like it when the dealers just send you home because "the computer said nothing"..
Does any mechanic still think mechanically anymore? They should test everything, computers are great and can pin point a problem or hardware failure, but misfire can be due to a lot of things. The computer don't make a genie pop up and tell you exactly what's wrong, most likely you have something that goes bad intermittenly.

 

Fortunately the computer is recording the misfires. It just doesnt always record which cylinder. Most times its just recorded as a random misfire. This time it actually recorded which cylinder it was. I think we're all just baffled at this point. No one has a clue.

 

You can try and raise your concern about the warranty, seems like they admitted there is a problem and work with you to fix it even when your warranty expire in a month.

 

if i were in your shoes, i would seriously consider having lexus buy it back from me. not worth all the hassle and you'll always wonder about the future issues if you keep it.