Help with mysterious prius issue

At that mileage I guess it wouldn't hurt I have 370,000 on my original fuel injectors and my car before I owned it was a one owner car owned by a family that drove four or five people to work everyday and the car sat in the parking lot came back home via the grocery store everyday for 240 some odd thousand miles till I bought it The only thing ever been done was a recall or two tires and small batteries nothing else nothing. I've also had one NZ the same engine we're discussing here in a few cars called Yaris which you're not detuned and are not hybrid very near bulletproof engines if even substandardly maintained very much similar to the two TC engine of old Corollas The hemi head one so I guess with any of them any of these basic problems could be your issue I would think in tec stream You would be able to see your injector firing patterns and what have you I would think if there was a problem in text dream it would orange the injectors the ballast whatever the problem it thinks you have and then you would look at that or replace that I haven't really had any problems with my fuel injectors but I feel I should have by now but I keep decent gas in the car and the car stays in the wind which is another reason I think these cars that do well are the ones that stay on the road not the ones parked at work all day but guys that are doing delivery and service work out of them kids that don't do anything but drive like hell and try to get there just partying and having a good time riding around visiting their friends whatever they're doing My wife has a generation 3 that should have had a blown head gasket 4 years ago but because the car stays on the road with Uber eats and all these other stupid companies she works with The car never comes home except for a few hours in the evening and then in the morning it's back on the road all day in the 100° heat whatever cars almost never turned off That's the only reason I believe it's still on the road today right now The hood's missing off of it she's rear-ended people twice she's backed up into people two or three times plastics hanging down from the bottom of the car etc etc but boy that car runs like a top never misses a beat because it's never off the road there's something to that I believe with these cars.

 

I think in the Toyota tax software if you were having injector problems and componentry problems like that it'll light that stuff up in orange for you to have a look at those particular specifications to see if they are in fact correct something's incorrect unplugged whatever maybe you need to get plugged up to that software and see what a health check says and if you have that software what does your health check say usually on these cars it's not going to be running rough as all get out and terrible in a health check say everything is wonderful and great fuel filters and delivery come to mind although in my 350,000 mi '09 none of this has been addressed I'm on original fuel injectors I don't think any fuel filter has been replaced I don't have paperwork for it hasn't been done on my watch and I'm sure my previous owners they did nothing guaranteed nothing. So fuel delivery and spark manufacturing definitely come to mind in a rough running scenario low compression although it would have to be quite low generally speaking could cause same again I would think the Toyota dealer software would pick up lots of these things or it seems it's been designed to It's like a rolling engine analyzer if you will or systems analyzer.

 

You can listen to the injectors with a mechanic's stethoscope.

You can check the long term fuel trims to see if there are any weird trends.

"mysterious" symptoms like these can sometimes be a simple underlying electrical issue: check the ground straps between engine and body- clean their connections or even just replace them on speculation. It's cheap and easy and won't hurt anything. Sometimes you can do a free test just by using a jumper cable to make a temporary bond.

Revisit spark plugs: there's a huge number of counterfeits on the market. Amazon and eBay are particularly notorious for continuing to sell them. Buy them across a local parts counter for best results. It's less convenient but it really matters.

 

Shouldn't make any difference. That battery is only needed to boot the computers and close the contactor for the high voltage traction battery. Once that is done, you get the READY light on the dash and the car makes all the 12v it needs until you shut down. But again, make sure that power is appropriately grounded between body and engine.

 

How's the coolant?

 

If Fuel Injector cleaner and a tankful of 93 octane makes it better......I might try newly rebuilt fuel injectors.Thats a lot of miles for one set.

 

The fuel trims might tell you if there's a fuel delivery problem, as Leadfoot suggests. If there is, it could be fuel pump or injectors (or an air leak, etc.).

We've had some threads here in the past that involved sending injectors to a service that restores them and sends back a report of before and after test results. Some details are here and here and in the threads leading up to those. In astrolink's case the injectors were the problem (as clearly shown by the problem going away with replacement, and the poor test results coming back for the old ones before restoration) and astrolink was happy. In CClay's case, they were not the problem (as shown both by the engine still misfiring after replacement, and the good test results coming back for his old ones), and he was disappointed.

The good thing about that approach is you end up with concrete evidence of whether you found the problem or not. To me, that beats just replacing some parts thinking they might be the issue, and then driving around a few days in that wishful-thinking state where you're hoping your butt dyno is telling you it's better.

The overall thing we learned from a few iterations of that were (1) the injectors are ok more often than not, and (2) when they're not, in-tank cleaner doesn't appear to do squat, but taking them out for bench cleaning gets them back to as-new specs.

 

BINGO! I have heard of bench cleaning and with good results but time is always short on my end....so I would have to buy rebuilt and recleaned ones and install them. let us know how yours work out...on a different thought if your fuel pump inside the gas tank is starting to go...would that cause misfires? Random ones? or just lack of fuel being delivered run rough due to the engine being starved of fuel?

 

check your fuel trims before firing up the parts cannon. A vacuum leak can cause rough idle and misfires on random cylinders.

 

I'd have to defer to a 2nd generation car owner, my c model is different.

 

Check where the 12v battery negative strap meets the body, as there can be rust/corrosion around the painted hole, or a loose fit on the bolt.

 

here in passenger side trunk area.

 

I pretty much begin almost every Prius diagnostic with; is there gas in the tank, oil level good, coolant pump circulating, then go to Dr. Prius for a quick check on the hybrid battery, and then hook up a bi-directional scanner to take the code dive. Too many times I've allowed myself to get distracted by errant codes that were being triggered by poor power conditions.

Each system is discrete, BUT, none of them function properly if not fed a proper diet of electrons. So, your new 12 volt may be the fix, but if your hybrid battery is failing (it only takes a few cells) you'll likely end up right back where you started in a week or two. If you haven't gotten Dr. Prius yet I'd suggest investing in the required Bluetooth dongle & downloading the app before all else.

I also use Liqui Moly engine & fuel system cleaners, engine flush, synthetic oil, brake fluid, and friction modifiers, and even with 300,000 mile plus vehicles I continue to see these 1.5 engines carry on without issue, and actually getting better than EPA w/o much effort. Purely anecdotal, but it's worked well for me, and I now care for dozens of Gen 2s and Gen 3s.

Just recently went through a similar condition on a Gen 3 that a local shop couldn't noodle through, and they had already hit their customer with a new 12 volt, terminal ends, plugs, coil packs, plug wires & boots, along with all sorts of fuel system cleaners, an oil change & filters, all to no avail. I swapped out their hybrid battery for a know good one and everything settled right down. They were scanning with an Autel, but got nothing. It was intermittent, and misfires in these little engines can sound and feel like you threw a rod, or worse, but as is very often the case, happy batteries cure most ills.

SM-N960U ?

 

In my experience IRL and helping people out here, I've seen the balance of risk often weighing the other way: you see more people eagerly jumping for some catch-all handwavey explanation about proper diets of electrons than you see people actually paying attention to their trouble codes and they turn out to be genuinely errant.

Now, some of the ECUs in the car do have trouble codes that are specifically for power supply issues. You can definitely get those codes if there are power supply issues, and they'll go away if those issues are fixed. Doesn't mean they were errant.

 

How did the fuel trims come out?