Do Prius injectors ever go bad?

In your gen 3 I doubt that's causing your knock after a 3-day startup You better start looking at the head sealing and water lock or vapor lock conditions . All fuel injectors can go bad they generally start to get clogged and don't deliver proper rates and their patterns can get kind of ugly like the spray can clogging on a can of paint by not using it correctly and all of that.

 

Have you cleaned EGR and intake?

 

Prius injectors can go bad, but they can also achieve ripe old age still working with flying colors.

For a while, we had a PriusChat thing going where people would send their injectors to a service in Michigan for testing and restoration, in exchange for the previous set that got restored. (I still have the last set that came back restored, on my table here, but they're the Gen 1/Gen 2 style.) And we would see the before/after test results for each set.

The 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. If I remember right, we did three sets, and astrolink's were the only actually bad ones, so they seem to hold up pretty well.

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.

Especially with the intensity of counterfeiting in the present day, in a lot of cases I would wait for a darned good reason before replacing parts that came with the car.

 

I wholeheartedly endorse injector resto/swap setups as @ChapmanF detailed above. Solved a few mysteries that way when I was into Subarus.

I won't hesitate to do the same for our Prius if/when it gets to that age & need.

 

Yes, injectors do "go bad". Whether one or more has poor spray pattern, or is restricted, or has incorrect winding resistance- it can happen.

The thing is, I (almost) never see injectors ONLY have problems during cold start. Usually if something is wrong, then it's wrong all the time. Sometimes injector winding faults show up when fully hot, but a restricted injector will always be restricted.

My point is, most injector faults will affect fuel control and therefore you can monitor fuel trim numbers in ECM data at idle and while driving. My 2006 is at 197k and total fuel trim is 0 +/- 3% most of the time.

0 +/- 5% is ideal. Up to 10% can be lived with. 20% is something wrong. More than that will set codes.
If only 1 injector is bad then most Gen3 should set P219A (balance) code.

Posted via the PriusChat mobile app.

 

At what miles, and was this before or after the cold-start symptoms started?

 

188k is pretty late in the day; may well be head gasket . That’s fairly typical scenario. Engine coolant level steady in reservoir?

 

Yes, injectors can go bad but it is pretty rare in a Yota/Lexus/Scion. Finding a Top Tier gas station and sticking with it is a good way to help them out due to the detergents that help keep them clean. (If you fill up at Top Tier stations you don't need to worry about gasoline additives to clean out the injection system.) If you don't always get Top Tier gas, or it's not available, adding a small bottle of fuel treatment/injector cleaner (like Lucas Oil) to the gas tank a couple times a year is a smart idea.

 

When I acquired my 2010 back in 2018, I started doing used oil analysis. It only had 90,000km on it but the reports were indicating problems with fuel dilution. I had everything taken apart to do the EGR so I sent out the injectors for servicing. The oil dilution problem is now solved. In my case, it was injector 3 causing issues with a poor spray pattern.


iPad ?

 

How many miles between oil changes?


iPhone ? Pro

 

I was on an 8,000 km hard limit oil change interval. I target 6 months but usually go by mileage not to exceed 9 months. I reduced to 7,000 km during the time when I was investigating this issue through to the next 2 oil changes after the injectors were serviced. The analysis showed immediate improvements following injector servicing and I went back to 8,000 km oil changes.

I have done some reading on similarly reported issues with fuel dilution of the oil in Prii and so this issue is out there and may be a natural side-effect of hybrids. Our non-hybrid 2015 RAV4 does not have this issue at all (I know, it’s not apples to apples).

Now, the previous owner used the car for many short hops and occasional long drives. My usage pattern is a mix of both. I also live in Ontario, Canada where winters are cold. To offset my short drives in winter, I use a block heater and grill blocking. Regardless, short drives are never going to fully warm the engine here so some increase in fuel contamination is to be expected.

My final solution to this issue was, in addition to the above, to switch to Amsoil SS 0W20 and now my viscosity numbers at drain are right on target and I could likely go beyond 8,000 km based on the consistent reports I’m getting back. The better quality oil is giving me improved margin for any fuel that’s still getting into the oil. My fuel dilution has improved from 4.6% to <1% and my viscosity at change improved from 6.8cSt to 8.1cSt.


iPad ?