05 L300 ran very rough then died - CPS?

[RogerC]

My son has an 05 L300 V6 with 260k miles. It was my wife's before it was passed down to him, and we bought it new.

The problem: It was running with low power and somewhat rough for a few weeks, then all of a sudden it started shuddering very bad, as though the engine was barely firing. If you stepped on the accelerator, nothing would happen. We limped it home by basically just letting it idle. Once we got it home, it only started once more. Now it won't start at all. There also seemed to be a strong smell of exhaust in the engine bay.

Would this be caused by a bad CPS? From what I've read, CPS issues tend to not be as violent as what we experienced. Could it be something else having to do with the ignition system?

My mechanic doesn't even want to mess with it because he doesn't think it's worth it, but we'd love to keep it running for my son at least through high school.

Thanks!

[flyingj]

What is the maintenance history of this car? With the 3.0L V6, you should have changed the timing belt at least twice at 100K and 200K miles along with the water pump, coolant and spark plugs.

Also, driving it with low power and rough running for a few weeks may have taken a small problem and turned it into a catastrophic one.

Without a history of how the car was cared for, and with this many miles on it, it will be hard for anyone here to start giving useful guidance on where to start. You will also want to pull the error codes that have no doubt caused the check engine light to be on for the past few weeks. This can be done by aquiring an inexpensive code reader or by having a local autoparts store pull the codes for you (assuming the car could be taken to them). This will start to give some insight as to what issue the car was experiencing.

Your mechanic may suspect a timing belt failure, which would result in bent valves and require a replacement or rebuilding of the engine. This may out weigh the cost of just replacing the car, but that is just one of a long list of posibilities of what could be wrong.

[fdryer]

In addition to what's asked, consider another long term reliability issue. Your car ran well for 260k miles. Nothing lasts forever. There are three catalytic converters; one on each exhaust manifold and a third one downstream. While there no mileage figures to dictate when catcons fail, they wear out from normal wear tear. Most catcon failures results in the internal honeycomb substrate disintegrating, falling apart and blocking exhaust flow - the equivalent of engine constipation. A partially or completely blocked exhaust system simply strangles the engine from running correctly. Either test for this at home or try a muffler shop experienced in these problems.

[RogerC]

Originally Posted by flyingj

What is the maintenance history of this car? With the 3.0L V6, you should have changed the timing belt at least twice at 100K and 200K miles along with the water pump, coolant and spark plugs.

Also, driving it with low power and rough running for a few weeks may have taken a small problem and turned it into a catastrophic one.

Without a history of how the car was cared for, and with this many miles on it, it will be hard for anyone here to start giving useful guidance on where to start. You will also want to pull the error codes that have no doubt caused the check engine light to be on for the past few weeks. This can be done by aquiring an inexpensive code reader or by having a local autoparts store pull the codes for you (assuming the car could be taken to them). This will start to give some insight as to what issue the car was experiencing.

Your mechanic may suspect a timing belt failure, which would result in bent valves and require a replacement or rebuilding of the engine. This may out weigh the cost of just replacing the car, but that is just one of a long list of posibilities of what could be wrong.

Thanks for the reply. Those are certainly fair points.

Timing belt and water pump were just changed about 6 months ago.

When I say "low power", I don't mean to give the impression that it was difficult to get up to speed. It was just less powerful than before. It would still cruise at highway speeds just fine, however.

The spark plugs have never been changed, which is one of the reasons why I'm thinking this whole thing could be caused by mis-firing cylinders (whether caused by spark plugs, CPS, distributor, etc). I've got a decent understanding of car engines and how they operate, and I've helped my dad rebuild engines (though it was 25 years ago or more), but I'm not educated/experienced enough to know exactly what kinds of symptoms problems in each of those areas would result in.

[RogerC]

Originally Posted by fdryer

In addition to what's asked, consider another long term reliability issue. Your car ran well for 260k miles. Nothing lasts forever. There are three catalytic converters; one on each exhaust manifold and a third one downstream. While there no mileage figures to dictate when catcons fail, they wear out from normal wear tear. Most catcon failures results in the internal honeycomb substrate disintegrating, falling apart and blocking exhaust flow - the equivalent of engine constipation. A partially or completely blocked exhaust system simply strangles the engine from running correctly. Either test for this at home or try a muffler shop experienced in these problems.

Sure. We're not averse to keeping things running for as long as possible though. I drive an 05 Toyota Sienna with 364k on it. It's my daily driver on a 130 mile round-trip commute everyday.

Thanks for the info on the catcons. I had no idea there were 3 of them stuffed up in there or even really given much thought to them going bad.

[flyingj]

Originally Posted by RogerC

Timing belt and water pump were just changed about 6 months ago.

When I say "low power", I don't mean to give the impression that it was difficult to get up to speed. It was just less powerful than before. It would still cruise at highway speeds just fine, however.

The spark plugs have never been changed, which is one of the reasons why I'm thinking this whole thing could be caused by mis-firing cylinders (whether caused by spark plugs, CPS, distributor, etc).

Well, glad to hear that the timing belt has been changed. The spark plugs are designed to last for ~100K miles. So at 260K miles, I'd say it is very likely that they are a cause for the misfiring. Honestly, it's impressive that one or more hasn't failed completely with that milage. Since they are not a prohibitively expensive and part of the prevititve maintenance schedule that should be followed, I'd start by replacing them and see what happens.

It wouldn't hurt to have the catcons inspected either, as fdryer stated.

[fdryer]

If spark plugs were never replaced, replace them asap. I replaced mine before 100k miles (car has 97k miles) and it was a pita. When removed and examined, they look just as fresh as when they were factory installed 13yrs ago. Exotic plugs using platinum, iridium and other exotic hard wearing metals are designed for 100k miles for engines tailored for them. One reason to replace them is the millions of combustion cycles that can wear down plugs from mechanical stress so factory recommendations to replace perfectly good plugs are to remove the possibility of leaving them in longer than recommended and discovering a broken engine from a plug disintegrating from extended use. While not likely to occur, replacing plugs as recommended is far cheaper insurance than finding out the hard way. Many get away with this from neglect or not worrying about it. Your choice.

And the sudden problems may be related. A young person getting a hand me down may find his new used car the chance to see how it performs in his own way, racing wherever he feels the need. If the car was used regularly and transferred to another driver with a different driving attitude, old age may reveal how old it really is when someone starts driving it as if it were new. Old well worn parts can last longer than anyone expects them to last, even under hard driving conditions. On the other hand, hard driving an old car may accelerate and reveal the worn out parts sooner. Some describe this as 'destructive testing'.