Running rough/stalling, after replacing MAFS and new gas engine

DanThorne

Newbie
Joined
Sep 3, 2022
Messages
4
Points
1
Make
Toyota
Model
Prius gen 3
Year
2010
Miles
260k
Engine
Hybrid + 2ZR 1.8L 4 cylinder ICE
Hi everyone, newbie here just joining the forum. This car's been pretty reliable. It's got some highway miles, but I'm not crazy about a new car until prices return to normal. I just replaced the gas engine this week at Gasket Masters (the old motor was burning oil badly, common with this Gen 3). A little after I picked it up on my long drive home, I noticed it started running rough & showing codes P3190 and P0101. I have a call into the shop & waiting for their feedback. They installed a long block so not likely anything like PCV or EGR, and those codes didn't appear. Meanwhile, today I replaced the MAFS with a new Denso, replaced the air filter, & reset all the codes. It ran alright for a bit. Soon after the 2 codes popped back up. The motor got sluggish, nearly stalling out, & makes a loud air whistle when the engine is under a load (I tried not to push it that hard). It's perplexing. I'm wondering if anyone's seen this before, and what the chances are that I got a bad MAFS from Autozone, or if there's something else going on that might be the root cause.
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,869
Points
63
Whistles always make me suspect a vacuum leak, but I urge you to quit throwing parts at it or fussing with it in any way until the shop that changed the engine has chance to make this right. Most likely is that something did not get reinstalled correctly, or got damaged during the engine change. There are so many things that get disturbed during an engine change that having something not go back right is not all that unusual. I would not consider the shop to be poor if they made such a mistake. However, if they won't step up right away and fix it, then they are flaky and you either have to get a different shop involved or get into some serious DIY trouble-shooting.
 

DanThorne

Newbie
Joined
Sep 3, 2022
Messages
4
Points
1
Thanks for the feedback and quick response, Bill. Was trying to tackle what I thought might be something simple before a long trip back into the shop
 
Last edited:

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,869
Points
63
OK, I understand. Look around for a loose hose end dangling; that doesn't cost anything.

If you are adventuresome, you could try loading the engine while standing still and listening for the whistle. Holding the service brake on hard should allow you load the engine pretty well. Obviously, you need somebody you really trust to jam their foot on the brake and give it throttle while you are under the hood listening for the whistle!

In my earlier years, I would take the hood off and ride sitting on top of the engine when trying to track down problems that only showed up at load or vehicle speed...
 

grcauto

wrench
Joined
May 29, 2014
Messages
1,423
Points
48
Hi everyone, newbie here just joining the forum. This car's been pretty reliable. It's got some highway miles, but I'm not crazy about a new car until prices return to normal. I just replaced the gas engine this week at Gasket Masters (the old motor was burning oil badly, common with this Gen 3). A little after I picked it up on my long drive home, I noticed it started running rough & showing codes P3190 and P0101. I have a call into the shop & waiting for their feedback. They installed a long block so not likely anything like PCV or EGR, and those codes didn't appear. Meanwhile, today I replaced the MAFS with a new Denso, replaced the air filter, & reset all the codes. It ran alright for a bit. Soon after the 2 codes popped back up. The motor got sluggish, nearly stalling out, & makes a loud air whistle when the engine is under a load (I tried not to push it that hard). It's perplexing. I'm wondering if anyone's seen this before, and what the chances are that I got a bad MAFS from Autozone, or if there's something else going on that might be the root cause.
I second waiting on the rebuilders.
 

DanThorne

Newbie
Joined
Sep 3, 2022
Messages
4
Points
1
Thanks for your feedback, guys. I'm working to get it back up to the shop and will follow back up with the outcome. Meanwhile one other issue that was resolved was replacing the failed HV battery pack from Hybrid2Go. The shop is going to honor the warranty and make it right.

Even with those 2 major replacements it's still far cheaper than new car prices @ $10k over MSRP. Has anyone else shopped for a new car this year? Surprisingly, neither Honda, Toyota, nor Hyundai budged on removing the dealer add ons, and would only negotiate them down slightly. The only one priced closest to MSRP was Nissan. I'm talking base model non-hybrid cars. It's nuts. Gone are the days of negotiating a markup from dealer invoice. They're all moving so few cars that they're basically in survival mode. Probably be this way until economy changes. I can't wait to get this old car cleaned up & back on the road again.
 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
13,010
Points
83
Location
St-Hyacinthe, Quebec, Canada
I urge you to follow the electric hybrid section of this site. I will be back in the game son. My sister died lately, that got me backed up on schooling.

family first. Had to get my niece and nephew squared away and good for adult school since my sister and their mom died.

I know this is not an excuse for not being more diligent on this site, as I made a promise a LONG time ago, I would come here till the end and give FREE advice for as long as I could.

In regards to your second gen prius, I am absolutely going to second my colleagues here, if they so wish me to say, cuz I really consider them good, you need to stop. Regroup, and watch MR weber. This is the best guy I have ever seen. Our school bought rights to his content to put it in french. This man is a genius, sadly, he ha a problem where he needs a wheel chair, not my domain to say what, even if I know, just take time, watch him.

Stay AWAY from the nissan. Unless you live in californium. Up here, those leafs are a night mare.
 

DanThorne

Newbie
Joined
Sep 3, 2022
Messages
4
Points
1
Hi Nick, I'm terribly sorry for you & your family's loss. Hope that you, your niece & nephew and family members are alright & taking care.

Thanks for the link to John Kelly's WeberAuto. The guy clearly knows his stuff.

I brought the car into a local shop & the finding was: bad catalytic converter. No amount of Cataclean would've helped because it was physically damaged & clogging the exhaust. Literally broken pieces of the honeycomb filter spun 45-90 degrees off axis. The MAFS error code might've just been a false positive from restricted airflow or back pressure. Good news is that the transmission (MG1/MG2), transmission oil pump, inverter, & inverter cooling pump all tested good. Mystery solved & waiting patiently through the national backorder on catalytic converters.
 
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