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Were there any other symptoms, such as laboring or stalling on hills?

 

Thanks for the input. With as many miles as I have on my 2005, I've been wondering about the converter. I get abut 42 to 43 mpg where I live. I'm in the sticks, uphill both ways out of town. In Seattle I get 50mpg, but it's all flat driving I do there. I may just pop into a muffler shop and have them check the back-pressure at the tailpipe so see if the converter's clogging.

 

Curious if this is something other then a hand near the tail pipe?

 

Yes, there are tests for backpressure. However, they're somewhat subjective. Often, if the converter is plugged the symptoms are,

• you can see it at night. The exhaust system cannot evacuate the hot gasses as fast as the engine can produce them. This causes the system to trap the heat. That can be measured, as well as seen at night. If the converter is really plugged up the converter, downpipe, and sometimes exhaust manifold will actually glow a dull to bright red from the heat. It is quite impressive.

• Since the Prius ICE is not always running, the exhaust system does get some breathing room. This means that the converters seemingly last longer. When the ICE is not running there still some backpressure traveling through that clogged converter. This problem sneaks up on you far slower than on a conventional gas engine powered car.

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• The vehicle loses power on hills. This is because all that loose debris falls to the back of the converter and plugs up the outlet. You pull over on the highway and turn of the engine. The pressure dissipates as you wait in frustration. You restart the car, and since there's no pressure built up in the exhaust system, you drive merrily away. When you top the hill the debris fall back down to the bottom of the converter and the backpressure can flow freely again... until the next hill when the cycle may repeat itself.

Tests can involve

• removing the pressure via a small hole drilled in the converter, or the piping and
• measuring pressure build up (if you're that sophisticated, me, I'm not). I have to admit, I'm not sure what the measurement is on a Prius, I suspect is different than on a non-hybrid gas engine. I've always done business with Mom & Pop exhaust shops most of my life. They'll simply

• rap on the converter and listen for falling debris in the converter.
• relieve the pressure by drilling a small, hole in the converter and seeing if engine power is restored. If the problem is not the converter then they can weld up the hole.

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• Measure the heat of the converter.

I also agree that the Toyota Dealer is NOT the place to go for this type of work unless you're kind of rich and willing to pour your bank-account out on the service desk. I base this solely on the price differential, not quality of parts or labor. I'd much rather deal with a good Mom & Pop place. They usually have a good reputation in the area and rely on word of mouth for new customers. I've yet to be let down by one.

 

thanks for the tip, never even thought about the cat. I bet mine is plugged up real well. The only problem is that with oil burning you will quickly plug up another cat as well. A simple answer is to replace with a test pipe, but won't pass emissions that way. If you cat isn't performing well you should be throwing codes p0401 and 402 too related to the downstream o2 sensor readings

 

Just a note that a bad cat is often a symptom of burning oil. If you just replace the cat without doing some things to reduce oil use, it will go bad fairly quickly. I would switch up an oil grade and use high mileage oil (probably 10W-40 or 5W-40) with as low of ZDDP as possible (ZDDP is an excellent anti-wear additive, but it's bad for cats when burining oil). Also, many here have reported reduced oil use after running injector/fuel cleaner or other engine cleaning methods. The theory is that the piston rings are getting gunked up and letting oil by, and so removing this buildup reduces the oil use.