Car Stalled, Won't Start, Running Rich (Please Help!)

[JJ_Is_Edge]

JJ - My reply is broken down into 2 segments. A somewhat useful segment. And a useless segment. I specialize in uselessness.

The somewhat useful segment: I agree with your direction to replace the engine and outsource the labor. If you're going to pay someone $950 to do the labor, make sure they're not just some backwood rednecks. I did that once, and it didn't work out so well.


The useless segment: I think you're letting this theory about it being rich cloud things. It generally makes no difference based on your direction though. Your direction is solid. But I don't believe even if it were running rich it would cause it to lose compression. It would appear your vehicle is a CVT, because you say it was a rental car. I'm not sure any place rents a manual transmission car in the U.S. But here's a for instance. Let's say your cam chain has seen a lot of wear, due to poor lubrication. It is my theory that Hertz never does even 1 maintenance on a car. They buy it, slam it out on the road, pull it off the road at some set miles and sell it. I would doubt they'd spend one thin dime to maintain it. Not having fresh oil in there could cause the cam chain to not get proper lubrication (along with everything else). Perhaps the cam chain could stretch enough to throw off your cam timing. Improper cam timing can lead to less than desirable, perhaps little to no compression.

There's lots of ways to lose compression. Bad oil can lead to ring wear too of course. Ring wear = low compression. I think the whole rich thing is perhaps not likely, but is beside the point in any event.

And as far as closed loop / open loop. I don't happen to know factually what a computer controlled engine does. But I'm a carburetor tuning expert. The vehicles I've had my AFR on will hardly even idle at stoich. So I have my doubts a computer controlled car shoots for stoich at idle. My LA 360 idles rich as a mofo at idle. And just get's plain *****y about idling when anywhere near stoich. I've got it idling in the neighborhood of 13.0 - 13.5 and it is still not that smooth. Cam timing and lift comes into play as well. But my LA 360 runs at about 12.5 - 13.0 at WOT and top rpm. And cruises at about 15.5. The only time it hits stoich is in transitions between power and cruising. I have to assume even modern day cars run similarly, not just aiming for 14.7:1 all the time. 14.7 wastes fuel when cruising, and could lead to burning a piston at WOT. But again, I don't know the fact as I have not applied an AFR gauge to my computer controlled vehicles.


7milesout

You are correct, perhaps I didn't articulate my point well enough. The car had been knocking a tiny bit but nothing major, and the running rich towards the end was likely a symptom and not the cause of the engine failure. I guess I just meant in addition to the headache of tracing down a run rich condition, which as someone else pointed out could be a red herring, there is likely at least another problem that may have caused some wear and tear that may come back to haunt me. This is just the simpler and hopefully better solution in the long run. Those are all solid points, bad oil could have caused some issues, the timing chain could have jumped a tooth, there could be a million things internally in the engine that are causing it to have no compression and they'd all be way more of a headache to chase down than just swapping in a lower mileage and (supposedly) improved designed engine.

I don't have personal experience with the shop I'm taking it to, as I'm relatively new to the area. That being said they have great reviews on google and when I called the junkyard to have the engine sent there, the guy said that shop buys a lot of motors from them so it would appear my car is in good hands.

Again, I can't thank everyone enough for all of your help.

[Top_Fuel]

An oil analysis would be interesting on the failed engine (wear metals, fuel dilution, etc.). But I can't blame you for kicking it into a dumpster and not worrying about it at this point.

[JJ_Is_Edge]

An oil analysis would be interesting on the failed engine (wear metals, fuel dilution, etc.). But I can't blame you for kicking it into a dumpster and not worrying about it at this point.

Where can I get it analyzed? I don't mind getting a sample and reporting back

[Loren]

If nobody's mentioned this, all of the engines are interchangeable. The minor changes in 2018 or so were internal. Roller cams, anti-friction coatings, stuff like that. Any 1.2 Mirage engine will drop in. Plug & play.

I don't know what happened to your engine, but they're NOT prone to that kind of failure. Get a Sub-20k mile used engine and be happy. It's not even worth trying to diagnose or repair your old engine. If it's got no compression, just replace it with a $6-800 used one.

Maybe do a post-mortem on it just to see what broke.

[Top_Fuel]

Where can I get it analyzed?

You can check out Blackstone Labs. A standard oil analysis is $30.

You can check out this thread where I have posted some oil analysis reports from my own Mirage.

[gone.a]

The vehicles I've had my AFR on will hardly even idle at stoich. So I have my doubts a computer controlled car shoots for stoich at idle....... I have to assume even modern day cars run similarly, not just aiming for 14.7:1 all the time. 14.7 wastes fuel when cruising, and could lead to burning a piston at WOT. But again, I don't know the fact as I have not applied an AFR gauge to my computer controlled vehicles. 7milesout

Once warm and in closed loop, the Mirage will idle at stoich as the ECU commands a lambda of 1. This is common to all the modern cars I have ever read about or looked at.

At wide open, it goes rich - reported at about 13:1 depending on your fuel type and how your gauge handles the conversion from lambda to air/fuel ratio.

Other than fuel cut off on decel I have only ever seen the ECU target stoich - even at low load cruise. Running stoich at low load cruise, will not lead to burning a piston in modern cars, in fact its desirable when balancing ecconomy, emissions, and power. Some modern cars will intentionally go lean (sometimes very lean) under low load cruise, but not mine or any Mirage I have read about.

For any OBD2 car you can get a cheap adapter and a free app on your phone to check this out.

Also, how are you measuring your AFR on your old cars? If you are using a tailpipe sniffer I have seen those read a whole point off from what a wideband reports. I always have to question AFR readings on older cars that use a sniffer. If the AFRs are correct, I guess its just a quirk of those old cars.

[foama]

I'd like to remark this kind of problem is extremely rare. There was a TSB about some cars running rich and developing a knock (as you said!) and then getting low compression. It was corrected by new software in the ECM.
I would certainly double check the car has the proper updated software so it doesn't happen again. For the same reason I would also connect a cheap universal OBD2 tester and look if it displays anything unusual. All better than getting the same problem again.

[7milesout]

Also, how are you measuring your AFR on your old cars?

Wideband AEM-0300, located as directed. I have a bung applied to each header, mainly to set the idle AFR condition. Once that's set, the physical set-up of the carb keeps the rest balanced. I didn't say 14.7 would burn a piston at cruise. I said it *could* lead to burning a piston at WOT. That and less power output at 14.7 and WOT.

I am aware of the emissions battle the OEMs have to deal with. I have a BT app on my phone and have looked at the O2 sensor reading from all my modern cars. A Lamda reading is easy enough to figure out, but after reading AFR as much as I have, my mind questions the Lamda reading I see.

And trust me, I wanted my 1972 Plymouth Scamp with an LA 360 to run 14.7 at idle. In an effort to reduce the smell of hydrocarbons as much as possible. But it absolutely refuses. Even 13.0 - 13.5 produces a very lopey idle even when warm. It sounds like it has a huge cam. It does have a slightly bigger cam than stock, but nothing insane. But mine sounds lopey like that because 13.0 - 13.5 is still a bit lean (for this engine / engine setup). I can richen it quick and easy at idle, and it smooths out fairly nicely when even richer. It just bothers me for it to be so rich. And the lopey idle sounds nice to certain ears. In any event, my manual choke richens it up even further when cold.

[JJ_Is_Edge]

I'd like to remark this kind of problem is extremely rare. There was a TSB about some cars running rich and developing a knock (as you said!) and then getting low compression. It was corrected by new software in the ECM.
I would certainly double check the car has the proper updated software so it doesn't happen again. For the same reason I would also connect a cheap universal OBD2 tester and look if it displays anything unusual. All better than getting the same problem again.

I have an OBD2 tester! My VIN doesn't come up as one affected by that condition (though I'm skeptical about that.) I'm going to look at fuel trims when I get the new engine in, and then if it is still running rich I'll consider other options.

[JJ_Is_Edge]

Post swap update #1:

The biggest take away is that I'm an idiot. When I first bought the car, it had a very slight engine noise that I had always associated with lifter tick. I did a few cursory searches here and decided that this 3 cylinder probably had some quirks and it was normal. Somewhere down the line the car must have developed a slight knock that got worse so gradually I didn't notice it because I am driving around with the new engine and it is completely silent, no noise whatsoever.

I'm a little agitated at myself as I likely could have had this covered under warranty had I been more diligent in taking it in before the 60k. That being said, this 2019 engine definitely feels like an improvement over the 2015 in terms of power/efficiency, and since it has such low mileage (9k on the engine) I'm hoping with regular oil changes and maintenance it will last another 5 or so years.

I am picking up the old engine this week so I will get an oil sample and report back for anyone curious. Additionally, as I have been driving I have been monitoring my AFR via Torque and it sits at 14ish when cruising, and 13ish at WOT. So I don't think running rich was the problem. I will monitor for a few weeks and report back if anything changes but it seems like I just had a bit of bad luck mixed in with some unintentional negligence on my part. Again, thanks everyone for your help, it was super appreciated!