Rough start after extensive cleaning and replacement parts

2012 Prius V with 175k miles. CEL came on P0301 and started to consistently get what I’m equating with the “death rattle” term i see in other threads.

After researching on this forum and countless YouTube videos, I decided to try all of the following, since we bought the car with 135k miles and didn’t know much of the service history.

Replaced spark plugs
Replaced ignition coils
Replaced fuel injectors
EGR pipe / valve / cooler removal & cleaning
Replace PCV
Intake manifold removal & cleaning
Throttle body removal & cleaning plus new gaskets
Replace coolant / oil change/ air filter
Oil catch

We initially only changed the spark plugs and coils but still got the CEL. After further research, we concluded we probably had the oil contamination in the intake manifold. Given how many miles and not knowing the service history and my son needing the car to be reliable, we dove in.

The EGR valve/cooler was by far the worst. Fuel injectors were completely gummed up. Oil consumption had been really bad. 1 qt low in 500 miles normally. Intake manifold had oil puddles in it.

After doing all of this work when we started it up, we initially got the death rattle but it was actually worse than before any of the work. No CEL though. We let it run for about 30-40 sec. Turned it off and back on the next time for close to a min. The third time everything started to smooth out. We decided to roll out of the garage and take a test drive. It ran great. I then took a drive about 15 min away and it drove wonderfully.

So here are the two questions:

1. Is it normal for it to be rough (death rattle) initially like this? Not sure what I expected but idling that rough initially after repairs wasn’t it. Worries it will come back.

2. Would you expect the hybrid drive to kick in more often? The norm had become less engine turn off at stops and just rough idling. Seems like it switches to EV mode much more quickly.

thx again for this forum. Extremely helpful!

 

I should have more clear. Replacing coolant wasn’t because of leak. We drained to avoid spills. Not knowing exactly which were coolant lines was a little frustrating, so we took the easy way out and drained bulk of coolant.

 

I should have also mentioned that the EGR pipe was about 75% occluded….cooler about the same maybe a bit less.

also, any recommendations on leak down/ compression testers or just borrow from local auto parts store? Seems like there’s a lot of crappy stuff available online…not sure how to evaluate quality of equipment. With 2 other vehicles in the 100k+ mileage category, this maybe something I may be using more frequently. Although the other cars we’ve maintained since the beginning so I know their condition and maintenance history.

 

Hi Raytheeagle, what is the purpose of the prolong harness?

 

Compression test yielded the following:
CYL 1 - 182
CYL 2 - 188
CYL 3 - 192
CYL 4 - 195

Scope and Leak down test tomorrow. Ran out of time today. Darn check valve failed after the first 4 tests. We were going to do a wet test, but then got side tracked on why the gauge was no longer holding air after first 4. Seems to me, the check valve must have an issue. We no longer had to release to air after. Rigged up a connection to compressed air and had the same result. Once air stopped from the compressor, the pressure in the line went to zero. Clearly the check value has failed. Tried some of the alternative valves that came with the test, all had the same result.

 

Initial pics of cylinders 1-4. Not the best. Trying again tomorrow after it charges more. Cyl 1 and 4 are closer up to to their timing and obviously 2 and 3 are further away.

 

Leak down test results- challenging to keep TDC:

Cyl 1 - 20%
Cyl 2 - 20%
Cyl 3 - 25%
Cyl 4 - 20%

1,2 and 4, slight positive airflow from oil cap.
3 slight positive airflow at tail pipe. No bubbling in the radiator. Oil and coolant do NOT appear to have mixed at all.Planning to do a piston soak, just based on possible things to “help” rings and valves.

based on the above, does anyone continue to think it’s a head gasket issue? Just following Eric the car guys philosophy…”we know, we don’t guess, we gather evidence “ I didn’t follow that approach from the beginning but now I’m a firm believer.

baeed on everything I’ve read so far and the evidence we have at hand, and given I missed the extended warranty on the pistons and rings offered by toyota, my conclusion based upon the facts would be shot rings or the inherited effect of a poorly designed gen 3 engine. On the cylinder where air flow was observed in the tail pipe leads me to the conclusion either the valve is not closing or TDC was completely achieved.

I looked at cyl 1 and 4 with them in the bottom position…looked the same as 2 and 3: lots of sludge.

I'm thinking of doing a piston soak. I don’t think there would be anything risked or lost in doing so.

thoughts?