Super cold (around 15 degrees) start this morning, engine started very rough

Cold soak rough start, there’s a T-SB for an updated EGR (original design could get stuck). Call a Toyota Dealer service department…


iPhone ?

 

I don't know about that particular device. It has to be able to read OBD II "Mode 6 on-board monitoring test results." Some of the cheapest scan tools can't, but my ~$40 one can. Several other PriusChat members (notably ChapmanF) know much more about electronic diagnostics than I do.

Good luck!

 

to be fair, people come here with problems mostly. that's what we see. there are people who claim 200k or more, never having done anything besides recommended service.
people who don't come here (the majority of owners) we have no idea what their problems might or might not be.
the only thing i can say from personal esperience is that i have less than 25k on my engine, and it's already exhibiting rough sounds and vibrations intermittently

 

Evidently rough starts happen occasionally even when these engines are in good condition, for reasons that remain mysterious. Something to do with water condensing in the manifold---maybe, among other popular guesses. Typically most likely the next time the engine is started cold after running only a short time at the previous cold start.

 

See the first couple of links in my sig, for some coolant strategies when doing EGR cleaning.

 

If you can’t clean your EGR and manifold til spring when its warmer. Do BG hybrid repair kit for now. It has 3 bottles, engine flush, oil additive, and fuel treatment. It will definitely help (or eliminate) your rough start.

If it does eliminate it though, don’t completely forget about the EGR comes spring time

 

"Blowing it out" doesn't clear it out. It depends on how bad it is clogged. You won't be able
to blow out the harded carbon parts. Oven clean WILL loosen it so you can spray it out with
a pressure washer.
The clearer it is, the better the flow, and the longer it will stay clear so the engine runs better.

 

Totally agree with your summary.
It's just forum speculation that 'slightly clogged EGR = Head Gasket replacement.
Is there someone that routinely does this extensive EGR circuit cleaning every 50k miles and still has the Dreaded Head Gasket problem at + 150k miles?
Is there someone that doesn't do any of this 'Off Manual' maintenance procedure and goes beyond 200k miles, no problem?
The System has a fault code if the EGR is not meeting it's requirement, correct?
We seem to hear only from the 'Do it' side...

I have a speculation that some of this Startup Rattle is related to a pool of moisture below the throttle body in the intake manifold that forms after shutdown.
That moisture may be from 'Carb Icing' just down stream from the coolant heated throttle body when driving in high humidity,
or from the moist foam that can form in the PCV hoses,
and when the engine is shut down in cold conditions this foam and or ice gets warmer briefly and collects at the low spot.

An oil catch can seems to collect some of that moisture.

 

Did not, never so.

Maybe I questioned individual car usage.
Mine is 80-90% interstate speeds.
Some may never get to highway speeds and putz around town the whole time.
Some have higher than average oil consumption.
Which would possible create more sputz in the EGR cooler?

At least I don't make nonsensical statements like this.

When you hear the rattle, that is faint 'hydro-locking' sounds of liquid water getting into the combustion chamber.
And it's BAD.

The EGR is a pressurized system pushing metered exhaust gases into the intake manifold.
And it's not working at idle.

But, please, go on. Tell us more!
What is your EGR cleaning maintenance interval? How long do you plan on keeping the Gen 3?

 

Funny how politicized EGR cleaning has become.

About a week back I did both the intake and the EGR components, second time around, in conjunction with spark plug change (the latter was due, by the schedule), over a couple of days.

It was near-complete overkill, but I had the wipers/cowl off, so hey. As much as anything it was just to refresh my memory of the process.

Started after lunch day one, knocked off around supper time. The next morning started putting remaining items back on, tidying up, kinda stiff and sore.

But compared to first time it went very smoothly; knowing the tricks helps, leaving a particular cooler nut/stud combo off definitely makes it easier, nixes the need to remove the rearmost cooler studs, and that coincidentally prevents the rear gasket from dropping down, getting lost.

The wipers and cowl are an unavoidable PITA: I've got one cowl bolt that I could not find a location for, s'okay. I've got one other left-over bolt, working too fast, didn't label: maybe next time I'll figure it out. If and when it happens.

For everything but the EGR cooler I used brake cleaner, brushes and rags. Oh, except carb cleaner on the throttle body (coolant lines still atached). The EGR cooler got the usual Oxi-Clean soaks, came out all nice and shiny:



Virtually no coolant spilled, with the preemptive 2 liter drain from the radiator trick. Poured back into reservoir after, it was a little high. After a drive, back to full line.

Bottom line: I would do this every 50k miles. Up here in Canada, maybe every 50k kms. I know...

 

I wouldn't do anything at all to that car based on one rough start.

Particularly if you use this as an uber car, and it is close to being too old for use with uber.

Just run out the clock as is.

 

Are we all somehow remembering a golden era of the past when gasoline engines all started easily and ran smoothly in super cold weather before they got warm (and all the children were above average)?

 

I remember that era, but don't believe it's particularly relevant. Occasional, seemingly non-head-gasket-related shaky starts of Prii (including mine) occur in mild weather, as well as "super cold." I don't know whether it ever occurs in super-hot weather.

 

"Super cold" was part of the story in this thread, though, and in my view it's not even surprising or especially remarkable when an engine starts sloppily in super-cold conditions.

When my Gen 1 was getting into the low 200,000s, it would sometimes outright fail to start (P3191) in super cold. The only difference between that and my remembered vehicles from earlier days is that those would fail to start right there in my driveway, while the Prius would drive me three blocks from home and then post the warning triangle and say "oops, never quite started."

Those rough starts can usually be improved by looking at all the usual suspects in aged engines. The impact is just greater in the conditions least favorable to starting anyway.

 

You hear the rattle when the engine is misfiring for any reason.
Saying "EGR is a pressurized system" seems only half true, at best. One end of the EGR path is pressurized only to the extent of exhaust back-pressure, which should be fairly small unless something downstream is clogged. The other end is at below atmospheric pressure when the engine is running. That sucks exhaust gas through the EGR components into the manifold when the valve is open.

 

Bill norton just fainted