2012 Prius DEATH RATTLE persists AFTER replacing EGR valve etc.

Any coolant loss? Did you remove the intake manifold and make sure all the ports are 100% cleaned out. The small ports where the egr feeds into the cylinders is the most important part to clean and gets gummed up. I have seen others clean the manifold but did not give enough detail in this area. I had 80% blockage and took more than a day of soaking and flushing to free all the carbon. I had pea sized carbon chunks shooting out where you see the water shooting through the egr pipe.



In this video they went to town on cleaning the egr section of the manifold.

 

I feel like you should’ve dealt with the misfire before tackling the egr system... is that misfire still there? Did you change the spark plugs?

 

try an oil catch can

 

These are the potential trouble areas. While it is easy to replace the spark igniters, I would say the probability that you have three failed igniters is low especially since the problem occurs only upon startup.

I am wondering whether the fuel pump is slow to build up pressure, thus causing momentary misfire upon startup. Try making the car IG-ON for a few seconds (from IG-OFF, press the POWER switch twice without depressing the brake pedal), prior to pressing the brake pedal and then pressing the POWER switch again to make the car READY, to see if that helps. The idea is to give the fuel pump a few seconds to build up pressure in the fuel rail before you try to start the engine.

 

Hopefully not, but could it be the head gasket? Any coolant loss? Compression test and leak-down test?

Also: Manifold Absolute Pressure (MAP) sensor: it's directly below the thottle body, tends to be completely oil soaked. Did you clean that, say with MAF sensor cleaner?

I too would say an OCC is in order, especially now that everything is cleaned.

 

If the system is factory clean, like a new prius intake manifold, the oil catch can would do nothing to prevent knock at first start up. The occ traps over time keeping a cleaner im or intake manifold. If the intake manifold was filled with oil/water/fuel starting the car would most likely cause knock. Bad coils are highly unlikely, burning oil from bad valve seals and or pcv/im/oil sucking into the combustion chamber with fowl plugs up creating knock. This incomplete or uneven combustion causes knock. Bad spark plugs, too much compression (oil/water/fuel/coolant) in combustion chamber, incorrect fuel (per compression ratio) etc. Smooth combustion is about balance with the correct air to fuel ratio, balance compression ratios on all cylinders, proper spark and valve timing.

Did you clean your egr cooler? A leak down test and compression test? Make sure all wiring harness' and plugs are firmly fitted. Hard knock at start up for 8 weeks will destroy a head gasket.

 

A dirty/leaking/bad fuel injector, can create insufficient combustion, knock and even flood a combustion chamber. The carbon deposits from the egr and pcv can make the outside of the injectors dirty, bad spray pattern or clogged. I would send your injectors to get cleaned tested or buy new. Fuel injector cleaner will do nothing. You need fuel (check pressure/spray), spark (check gap you have new plugs), compression (check compression/leakdown). These are the only things i can think of if everything is clean. Check for vacuum leaks, any leaks can create fuel pressure problems. Vacuum controls fuel pressure via ecu.

 

Head gasket can be done without pulling the motor but may take the same time as pulling. The timing chain cover is a pain in the a s s. I asked if you had any coolant loss. If you had pulled the plugs you would see coolant in the combustion chamber. White smoke from the exhaust is the other indicator.

 

Head gaskets can be done without pulling the engine, but the published book time takes engine removal into consideration.


iPhone ? Pro

 

After doing the intake mani cleaning, and egr cleaning (thanks @NutzAboutBolts for the awesome youtube videos) the car drove fine for an awesome 500 miles, 2-3 weeks. and then out of no where, the CEL's for misfire cyl 1 came back.

@danlatu
My coolant overflow tank was most definitely low on coolant. Well below the "low" line.




The only things I have NOT done, that I can brainstorm:
-clean or replace injectors
-leak down test
-compression test

 

I was tempted to make my own thread, about my on going "shakes on startup" issue and misfire CEL's, but I didnt want to clutter the forum. If anyone has some spare time, would you guys kindly see my thread over from club lexus? its losing steam over there, as I think the few users on there are out of ideas:

Chargerfan - First Problem Detected 117K: Engine Shake On Take Off And On Start Up - ClubLexus - Lexus Forum Discussion

(mods, if linking to another forum is not allowed, please advise and I shall delete)

 

Get an inspection camera and inspection cylinders 1 and 2. Between the cold start misfires and low coolant level, there is a decent chance that you have a head gasket leak.


iPhone ? Pro

 

The low-hanging fruit in the above is the two tests. I would have to watch videos myself, to recollect just how they're performed, what you're looking for, but I believe they're quite effective at diagnosising head gasket failure. A compressor tester is (obviously) required, and I believe leak-down requires additional gizmo.

Looking through the attachment from the Repair Manual on compression testing, Techstream is mentioned with tedious regularity. Maybe @NutzAboutBolts knows some work around, if it's possible to compression test (and leak-down test?) without Techstream?

You could always let dealership do the deed.

 

*gulp*

I was hoping the words "head" and "gaskets" would not be mentioned ....

okay, so thats my plan of attack than .... leak down and compression test. wish me luck all, will report back in a few days

 

Here's inspection mode info, mentioned in the above: