2011 Prius IV Having Trouble Getting Air In / Breathing Can't Figure It Out

Hello All,

I'm a long time lurker on Priuschat and never had the need to post. Any problems I've had (nothing major) were addressed here previously so all I had to do was refer to past postings.

I own a 2011 Prius IV that I purchased when it had about 165,000 miles on it. It now has about 230,000 miles on it. I'm a maintenance fanatic in general, so I've done quite a bit of work since my ownership started. The car has been really good to me.

Thank you to everyone on here who freely contributes their knowledge. There is a wealth of information in previous postings, which is a good intro to this, in all honesty.

Here is my current problem. I welcome any input, and would appreciate any troubleshooting tips if nothing else, so I can at least narrow down what the problem might be.

My mechanic doesn't even want to think that his shop caused this, so I'm going to a new mechanic on Monday and I hope to give him some sort of starting point at least. Of course, I'm quite curious myself.

Here we go.

I brought the Prius to my long time mechanic to have the following work done:

Replace PCV Valve

Replace EGR Valve

Replace EGR Cooler

Replace EGR Pipe

Clean Intake Manifold

Clean MAP Sensor

Clean MAF Sensor

The good news is the mechanic only touched those things so my problem is somewhere in there.

The bad news is the mechanic touched all those things so the problem could be any of those.

Thanks to this sub, I learned about the EGR issues with this generation of Prius, and decided to just replace everything instead of trusting the mechanic to clean the old parts properly. I do have them and have to get around to cleaning them sooner or later, but the car sure needed the servicing.

So on to the problem.

About 3 days after I got the car back, I noticed the car started to idle quite rough. It definitely sounds like it is struggling to take air in.

My MPG also went down from about 48mpg on average to about 38mpg on average, with no change in driving habits, route, nothing. Certainly nothing that would cause a 10mpg drop. Quite annoying because I was hoping the MPG would go up not down with the EGR service.

Things I noticed while trying to solve this:

If I disconnect the 12v battery to reset the computer, the rough idle will go away for about 2-3 days (not sure if this is a function of simply time or how many times the car is started) but the MPG drop remains.

The rough idle only seems to happen when the engine is charging the traction battery, so when the battery shows about two bars.

I recorded the actual idle sound but can't post it yet because I don't have enough posts and I didn't want to "cheat." If someone can allow me to before I reach the posting amount that would be awesome, or I can just wait until I get there.

It is definitely NOT the head gasket, knock wood. That is obviously a very distinct sound, and I listened to it on youtube from several sources. The sound all sounded the same, and the sound my car is making is absolutely NOT that sound.

My sound definitely seems to be tied to having trouble with air and/or breathing.

So that's my issue. I'd appreciate any thoughts, definitely. If more info is needed or any questions please ask.

Be gentle, lol. I hope I'll be able to give back many times over.

Thank you everyone.

Sincerely,

Frank

 

Oops, I forgot something. It's not throwing any codes.