Brutus213

Hi....just bought a used 2007 gs 350 in Feb....seems to be in excellent condition....I'm afraid it has tuned out to actually be a lemon.....radiator had to be changed within a month of purchase and now the check engine and check vsc came on..changed spark plugs and one coil....its always cylinder 6 that misfires....tried switching the spark plug and coil to see if the code shifts....same always cylinder 6.....my local mechanic is at a loss and told me it's likely electrical and to take it to the dealer......tracked down the dealer that did work on this car with the previous owner.....turns out major engine work was done in December ( 6 months ago) related to a misfire.....and now I'm having the same problem.....probably requires majot engine work again....any idea what the problem could be ? Any advice? The dealership will get back to me wit details next week...I'm hoping that since they worked on it less than 6 months ago they'll fix the issue for free but I doubt it.....and btw...it is also burning oil.....I'm at a loss bought lexus thinking quality and longevity....it's the worst car I bought ever....thanks for your help in advance....

Sodium

Sorry to hear that you're having these issues! On the other hand, you did purchase a car that has been in service for about a decade, and that's always a bit of a gamble. At this point, you can't reasonably blame Lexus for your car's issues – I have no doubt that the previous owner(s) weren't very diligent with maintenance

Did you get the car from a dealer or a private seller?

EDIT: It may be something relatively simple, like one of the cylinder 6 fuel injectors being bad. Also, check the air filter to see if it's excessively dirty. And oil burning could be down to a bad PCV valve

sprtn131

This is what a mechanic should check for:

spark at the plug/from the coil.

Fuel going to the cylinder, injector pulse, fuel pressure drop, resistance test, injector currant ramping with a lab scope.

Compression test/cylinder balance test.

If these test are performed there should be a clear failure

Brutus213

Thanks for yur responses......I'll just take it in to a lexus dealer and see what they say....I'll as them to check the items you mentioned.....hopefully they don't come back with some sort of an engine rebuild required or somthing ridiculous

Brutus213

Update: didn't take it to the dealer as their prices were insane....took it to T-Lex in Toronto, reputable Lexus experts according to several suggestions over Lexus forums....Basel was great, indicated that he thinks its most likely that the culprit is a leaking fuel injector. Ofcourse we have two injectors per cylinder and we don't know which one it could be unless he goes in. He'll be looking into it shortly, hopefully this solves the issue. Basel seemed very knowledgeable so that brings me a little comfort. Price wise its still going to be around or over a grand depending on which injector or if both have to be replaced......i'll keep you posted after the work is done to see if the issue is resolved.

sprtn131

just curious about how he concluded that the fuel injector is leaking? Did he do any testing? Injector drop test? Look at fuel trim on a scan tool? Check spark? Or compression? I'd hate to see you waste tine and money on a hunch

Brutus213

Update: I was told that it wasn't the furl injectors that were leaking....mechanic thinks that the head gasket is leaking small amounts of coolant into the 6th cylinder.....the engine is running way too smooth for it to be a gasket leak....now I'm on my 3rd mechanic....3rd guy agrees that it doesn't look like a head gasket leak....compression test came back fine...there was alot of carbon buildup in the engine likely from theprevious owner running regular gas......cleaned up the engine and seafoam treatment.....ran fine for half a day and misfire again....will take it back tomorrow to investigate further......still no idea what is causing the misfire......

sprtn131

What were the compression readings per cylinder? Or did they only check the one? And ask them what the fuel trim readings are (short term and long term) These things matter. Positive = lean. Negative = rich

SILENTM

Have your mechanic put cylinder 6 piston all the way down, then have him look down the spark plug opening with a borescope and mirror attachment to see if there is any scoring on the cylinder walls.