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Parris Boyd
User Rank
Iron
Re: Recall?
Parris Boyd   10/17/2013 3:37:30 PM
NO RATINGS
Overtures to NHTSA (by Spyderchat, et. al.) have been rebuffed based on the "safety" issue (frankly, I think an engine suddenly disintegrating DOES have safety implications), so it seems the EPA should get involved given the environmental considerations, appropriately highlighted in several other comments. I've focused on that angle in at least one blog post: http://uc2.blogspot.com/2013/10/toyota-told-to-conduct-awareness.html 

GTOlover
User Rank
Platinum
Re: Variable Valve Timing
GTOlover   10/17/2013 2:27:06 PM
NO RATINGS
Not that I condone tampering with emissions devices on newer vehicles, but on a 1987 I would take off the cat and empty it. Put the shell of it back on the car for appearances.

I look at it this way, there are very few old cars running around and that number is dwindling. A few here and there with some of the emissions surpressed is not as big a deal as new cars not working correctly. In the case of this Spyder, they were crapping out with very few miles on them! Unacceptable. As a previous commentor pointed out, the engine failure was an even worse enviromental hazard!

1800ES
User Rank
Gold
Re: Variable Valve Timing
1800ES   10/17/2013 1:57:05 PM
Catalytic converters ARE a caution, in my 1987 Volvo wagon, the 'orange' of catalytic material came loose inside the converter shell.  It wasn't too much of a problem on level ground, but it would roll back and plug the catalytic converter outlet when going uphill....Talk about loss of power!  Pulling over, and reduced exhaust from the engine would allow the 'orange' to roll away from the outlet, engine would run just fine- It took a while to figure out what was going on!

Rob Spiegel
User Rank
Blogger
Re: Variable Valve Timing
Rob Spiegel   10/17/2013 10:25:26 AM
NO RATINGS
Hey Jake, this problem isn't so much because of envirnmental equipment, it's because of faulty environmenal equipment. Most -- if not all -- of the other car models with pre-cats are doing just fine.

ab3a
User Rank
Platinum
Re: Variable Valve Timing
ab3a   10/17/2013 9:41:55 AM
NO RATINGS
The point of installing environmental controls is to lower the waste and effects on the environment.

At some point, we have to ask whether there is an environmental return on the investment. Here we have entire engines self-destructing after only 30k miles on them. How environmentally sound is that?

Please don't misunderstand me, I'm not ranting against environmental controls, I'm only trying to find the most efficient way we can deal with the methods themselves without causing undue harm to the environment just by it being there. 

 

Jake Brodsky

GTOlover
User Rank
Platinum
Re: Variable Valve Timing
GTOlover   10/17/2013 8:59:42 AM
tekochip, I also found information related to incorrect bore and hone of the cylinders that may lead to an incorrect break in of the rings. This leaves the bore oval and oil bypasses the rings and settles on the precats. The burning off of the oil may lead to the precat failure. Toyota changed the bore and hone of the cylinder late 2002 early 2003 (no one is quite sure). This seems to take care of the ring break in issue. Many also speculate that the precat was revised at the same time. Seems Toyota isn't really saying and most of what I found on the web is conjecture and theories.

One universal on the web, the failure is catastrophic. Other recommendation, take off the exhaust manifold and knock out the precat! I have seen recommendations to do this to the newer models after 2003. Seems that the engine will pass emissions when at operating temperature (mandatory lawyer clause of not responsible for this information if you fail your emissions test).

TJ McDermott
User Rank
Blogger
Recall?
TJ McDermott   10/16/2013 11:25:20 PM
NO RATINGS
Toyota may have discontinued the model in the US, but that wouldn't protect them from a government mandated recall.  Or do those only apply if safety is on the line?

Parris Boyd
User Rank
Iron
Re: Variable Valve Timing
Parris Boyd   10/16/2013 12:48:45 PM
NO RATINGS
Great post - explains the "ins and outs" (pardon the pun) very clearly from a technical perspective. Especially informative since the question has come up in other forums as to how material from the pre-cats finds its way into the engine. Thanks for your help.

Rob Spiegel
User Rank
Blogger
Re: Variable Valve Timing
Rob Spiegel   10/16/2013 10:34:53 AM
NO RATINGS
That's a very good description of the problem and how it affects the vehicle, Tekochip. This seems to be a widespread problem with this model. A quick Google search found tons and tons of references to pre-cat problems.

tekochip
User Rank
Platinum
Variable Valve Timing
tekochip   10/16/2013 9:35:32 AM
Another example of complex systems failing in complex ways.  As the pre-catalyst fails you would think that the exhaust gas pressure would keep all the containments from flowing back into the engine, but the MR2 engine features variable valve timing.  Under some conditions the valves change their timing to allow a little exhaust gas back into the cylinders, sort of a vale timing version of EGR.  So, with the variable valve timing sucking in exhaust and the pre-catalyst failing, the result is containments scoring the cylinder walls and valves.


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