redmethods

I got a VSC code a few times & I took it to the dealer.
They said it was a random misfire on # 3. Since the warranty is out now .Hey want $600 cda to do a top end cleaning. Change the plugs, change the oil, add something to each cylinders, then change the oil again.
The car has 76000 km (2006)
The car runs fine , so I was thinking about just doing the plugs.

What do you guy think?

LDNN

Can you get a second opinion from an indy repair shop? And if the diagnosis is the same ask the shop how much it would charge for the same work the dealer listed.

GS4_Fiend

iTrader: (22)

If it's only misfiring on cylinder #3, your problem area would be the ignition coil, fuel injector itself and the signal to the injector, last would be compression. Also check the spark plug if it's in good condition. Try swapping coils if anything changes. If both are good then your problem would be fuel injector, then compression.

Sffd103

iTrader: (16)

Is it a 250? If it is you can tell them that the car is running sluggish and that it almost stalls. There is a TSIB for carbon buildup. Not sure if that's done if it's out of warranty though.

RandomTech

I'm not saying it couldn't be these things, but from my experience it isn't the injector, injector harness, compression, or plug. All would cause consistant misfires and a flashing check engine light.

You're going to need to pull the intake manifold to swap coils around to diag the #3 coil anyway, so while you're at that take a flashlight and look down onto the back of the intake valves. I bet they look like *** covered in black barnacles. If so, and the misfire doesn't follow the coil, you've got a carbon buildup issue.

Another (far less precise) way of diagnosing a carbon deposit issues on the 250 is as follows: drive around at high RPM (5k+) for a few minutes, on and off heavy load and WOT. Come to a stop, idle a bit, and then give the throttle some small blips. Car shaky when it returns to idle? You've got carbon breaking off and holding the intake valve open, causing a partial misfire.

Lexus has a TSB for the 2006 250 replacing the valve springs with stronger units (they blast through the carbon better). I've had success with the top engine clean that the dealer recommended as well. A more recent TSB has the dealer re-ringing the pistons to deal with persistent, severe misfires caused by the carbon breaking off and damaging the compression rings. This is diagnosed with a boroscope and a compression test. It is also extremely extremely rare and usually coincides with horrible maintenance.

Also, welcome to owning a direct injection car. All manufacturers are having this carbon issue.

tl;dr - do the top engine clean

Jeff Lange

iTrader: (1)

From his profile, he has an IS350, which of course due to the D4-S system does not have the carbon issue, so the top-end clean and TSB's related to it are not really applicable.

Unless he has an IS250 and his profile is incorrect or related to another car.

Jeff

RandomTech

I'm baffled as to why they would want to do a top end clean then.

redmethods

Sorry Guy I guess I should have said, yes it's a 06 IS250 AWD.

Jeff Lange

iTrader: (1)

That makes more sense, and in that case I'd probably recommend doing the top-end clean as well.

Jeff

hades281

RandomTech -- (I assume by the username, you work for Lexus?) So what you are saying, is that the piston ring TSB is not a preventative treatment for carbon buildup which prevents it from reoccuring in the engine. The TSB is to replace compression rings damaged by chunks of carbon.

Does that mean that there still is no remedy for the buildup in the first place? The fact that the engine is being destroyed internally by the carbon is alarming to me.

How big are these carbon chunks that get lodged between the head and the intake valve?

Jeff Lange

iTrader: (1)

The TSB is intended to help with the carbon buildup as well as any oil consumption issues. If there are any issues beyond that (damaged pistons/rings/scored block), it would also take care of getting that replaced as well.

Jeff

RandomTech

This can potentially happen with all direct injection engines. It is rare on a Lexus to see severe damage. I've personally only seen one IS250 need an engine for this issue. The customer got a shorblock, both heads, and all new intake valves goodwilled by Lexus. Many dealerships goodwill the top engine clean if you're just out of warranty and have a good dealer service history.

The bits of carbon are big enough to hold open valves, yet fit between the piston and cylinder walls.

You can help prevent carbon deposits by regularly changing your oil, using synthetic, and running a fuel induction cleaner every 30k miles.

VIS250P

iTrader: (1)

If the top end clean dont work, then well it is time to do o-ring piston job...

RandomTech

This isn't necessarily true. Cars that need new engines have severe, constant misfires that coincide with moderate to severe oil consumption (not always, but usually).

Sometimes it takes two top engine cleans (and a lot of soaking of the intake valves) and a few hundred miles of driving to push all the carbon barnacles out the back end. Even then, if the misfires persist, it's more likely the valve seats are damaged over the rings. Diagnosing with a leakdown/compression test is required before a good tech will condemn the rings or what-have-you.

Unless it's a warrantee job. Then they'll just put a new everything in for you per the TSB to make sure it is fixed.

plmeeker

warranty wont cover it because it has more that 70k, but there is a tsb for the top engine cleaning for that car. if it falls within a certain vin range the dealer will put new pistons in it (another tsb) call the dealer and see if it qualifies.