New lfx engine

[moE_09]

Originally Posted by Russell James

How many miles? And how frequent were the oil changes?

A plugged cat can damage an engine, I've seen it a few times. GM even put out a bulletin. Started happening more often when cats moved very close to the engine. You're right though, it is rare, but possible.

Crudded up intake valves another possibility. Especially if the miles are getting up there and there has been less than frequent oil changes. Cruddy oil and a DI engine do not mix will, intakes can get carboned up.

If nothing turns up with the basic checks of ignition, fuel, sensors.... then look at the mechanicals with a leak down test. Then possibly remove the intake and look at the intake valves with a boroscope. A leak down test and look at the intake valves with a boroscope will tell a lot about the engines condition.

The oil changes were always on time. I don't rmr the mileage but always had about 15%-20% oil life left. Once it was left until 5% oil life. I have 24K miles on ur car itself and idk how to do those tests. And I'm starting to lose trust in my dealer, 99% of the time the misfires ony happen after 5K rpm. I can be going 100mph but I keep it under 5k to get there no misfires occur

[TommyTheCat]

Originally Posted by maddoggyusa

TommytheCat... who died and made you the chief mechanic? Half of your rant is plain wrong... and I find it hilarious you calling out other people.

A few misfires won't kill your cats. A plugged cat killing your engine? Yea I'm sure there are some rare stories but I've replaced lots of plugged cats on engines and they're fine. Yes, the cold has caused lots of misfires in the Wintertime. There were lots of people on these boards this winter having problems. The problems went away.... probably caused by intermittent wiring/connector issues due to extreme cold temps. Smelling coolant in the cabin can mean a leak in the cooling system anywhere! Not just the heater core. Walmart isn't stupid enough to not put enough oil in your vehicle. Like almost all shops, you typically pay extra for more than 5 quarts.

You have some good advice mixed in with some nonsense.

Lol don't be an idiot... I didn't call anyone out. I think it's funny people still remember points is all, that's not calling anyone out. And I never said a few misfires will kill you cats, but they can over time especially if they're flashing the MIL. So don't assume anything. I've had plenty of cars where there is enough exhaust backpressure from clogged cats that you won't start the car, and lack of power is the number 1 symptom... so I don't know why you're complaining about that. The cold does not cause a misfire on a car. Is it easier for a car at cold temperatures than at normal temperatures to misfire? Yes, but that's not the cause of the misfire. And I have three walmarts that send me work from my local area, and plenty of their untrained techs have been stupid enough to strip drain plugs, leave filters loose, and leave oil overfilled or underfilled. I've had them use diesel oil on cars that require 0w20. People can be stupid. Sorry if I offended you by talking badly about Walmart, you must work there. I'm sure there are some competent people there, but after fixing 100+ cars from them in less than a year I tend to recommend people to go to actual mechanics that are legally allowed to work on cars. (At least here in CA, if they mess anything up they're not allowed to do anything other than batteries, tires, and oil changes because they're not licensed mechanics)
So I don't know what your problem is, I haven't lied about anything or called anyone out but you, for being dead wrong about what I said. When I'm talking about those cold temperatures I'm talking about reasonably cold. Name one thing that was nonsense... Remember this isn't a diesel, where you've gotta plug in cars to be able to start. It's an LFX

[Red2014SS]

Originally Posted by moE_09

The oil changes were always on time. I don't rmr the mileage but always had about 15%-20% oil life left. Once it was left until 5% oil life. I have 24K miles on ur car itself and idk how to do those tests. And I'm starting to lose trust in my dealer, 99% of the time the misfires ony happen after 5K rpm. I can be going 100mph but I keep it under 5k to get there no misfires occur

If it runs good at lower rpms, take all of your mods off of it, clean it up, take it to a different dealer and trade it in. You eat a loss by breaking the lease early, but you'll save money in the long run.

[maddoggyusa]

Originally Posted by TommyTheCat

Misfire because of the cold? Never. This is 2015... direct fuel injection. Tell that guy who told you the cold will cause a misfire, especially on a single cylinder, he's an idiot. It won't.

Read what you wrote. direct fuel injection has nothing to do with preventing misfires. Most misfires are related to lack of spark... e.g. bad plugs, bad coil, wiring, etc. And yes it will be at a single cylinder. But could be something other like poor compression for OP's situation.... or could be a bad cat like you said. But the bad cats are likely the result of something else (like a bad tune) and not the initial cause.

[TommyTheCat]

Originally Posted by maddoggyusa

Read what you wrote. direct fuel injection has nothing to do with preventing misfires. Most misfires are related to lack of spark... e.g. bad plugs, bad coil, wiring, etc. And yes it will be at a single cylinder. But could be something other like poor compression for OP's situation.... or could be a bad cat like you said. But the bad cats are likely the result of something else (like a bad tune) and not the initial cause.

I never said that the cats were the initial cause. They don't melt down on their own, but it's harder to diagnose a car if the exhaust is restricted.
I don't mean that direct injection prevents misfires, I'm saying the days when the cold would keep gasoline cars from running properly are done. Carburetors that need to be warmed up in the cold mornings don't come out the dealer anymore.
The reason I suspect his cat could be clogged is because he drove around with a misfire since he first bought the car, and the other cats got clogged as well (though since they're smaller they'll clog quicker). If he drove around with a misfire on number 6 and now the rest of the cylinders on that bank are all misfiring then there's something wrong on that bank... Something like restriction, or compresson, or as you said spark/fuel. I advised getting rid of the tune too. But he also said the car misfired when he first got it, before it was tuned


Cats hardly ever cause misfires. I didn't say that they do, I said they CAN cause lack of power or even no-start conditions... but diagnosing a car's other problems with clogged exhaust is easier said than done. It's best to check first

[moE_09]

Sorry for bringing back the old thread. The dealer said I might be in the new engine department. he's gonna let me know for sure this week, do I contact gm service ? Do I go to court or do I agree and put in a new engine. Any advice on what should be done?

[kmarshall2121]

Originally Posted by Red2014SS

Keep in mind that he leased this car. That means he only paid to use it for so many years/miles. When he returns it, it needs to be worth the agreed upon value at the time of lease. A car with a used/replaced engine is not what the dealership will be expecting come end of lease. It will hurt the resale value of that car, and they'll expect him to cough up the difference or buy the car.

I would fix the engine that's already in it. I think the dealership is trying to rip him off instead of fixing the car.

What?!? Dealerships 'rip' you off?? NOOOO! tell me it isn't true!!!

[hinfv]

Anybody know how much a new engine goes for? And about how much labor would be. I'm debating weather to trade the lease back in and pay and it not being my problem or throwing in a new engine, whichever route is cheaper

[maddoggyusa]

Originally Posted by moE_09

Sorry for bringing back the old thread. The dealer said I might be in the new engine department. he's gonna let me know for sure this week, do I contact gm service ? Do I go to court or do I agree and put in a new engine. Any advice on what should be done?

if it's covered under warranty, YES let them put in new engine.

if it's not covered under warranty, READ ABOVE and try to save your $$$

[BigRedViking]

What was the procedure that fixed it the first time it started misfiring? After you got it back from repairs then you started modding, correct? Then later on down the road it started misfiring again, correct? I know a certified GM tech, I'll ask him about it tomorrow. So, elevated coolant temperature, misfiring cylinder 2,4,6 under heavy load(started on cylinder 6), coolant loss (but not a dry radiator), catalytic converter failure (both? Or just 2,4,6 bank) automatic, or manual car? Does this dealer get good reviews for service?

[VTSummit]

At least a couple of posts crapping on dealers, but the guy obviously doesn't know anything about the car and mods it- has problems and still continues driving it? And the dealers suck?
Warranty won't pay for a tech to spend a bunch of time diagnosing your car. If you pull out the wallet and pay for someone to diagnose it you may save a ton of money. As for swapping a used engine in- I don't see how that would be a problem as far as the lease. Your insurance company would do the same thing if the engine was blown by an insurable event.

[BigRedViking]

My friend the GM certified tech says it's likely to be carbon build up, and a failing water pump. Hopefully that's your problem, but you should find a reputable mechanic to diagnose the issues.

[moE_09]

Originally Posted by BigRedViking

My friend the GM certified tech says it's likely to be carbon build up, and a failing water pump. Hopefully that's your problem, but you should find a reputable mechanic to diagnose the issues.

Thank you. Ill to ell them about the water pump. They said a valve job should fix it now and that'll be out of pocket. So let's hope it does

[Vroom_vroom]

Slap a catch can on it when it comes back!