[V8] Clogged Cats? - '90 V8q

[urq]

... based on your description you may have cat issues ... but I suspect 
you've got more than that causing the problem ... I can't see any way a cat 
problem will cause the tach to drop ... that with the "dies until the engine 
cools" sounds a lot like a speed sensor to me ...

I wonder if the engine isn't running excessively rich too ... that would 
cause the cats to overheat and be damaged as well ...

Read the codes ...

Steve B
San Jose, CA (USA)


> Hey all,
>        Sold that '90 V8q I sold long ago started acting very strange for
> it's owner.  I was out there to take a peak and I'm thinking that it's a
> clogged-catalytic problem based on what I can see from the outside.  I'm
> looking to see if anyone has alternate ideas.
>
> Description:
> a.  car starts up from cold perfectly
> b.  warms up fast in water-temp, faster than I've ever seen
> c.  exhaust flow at the tip seems minimal air, but super-hot.
> d.  car is drivable - but a bit sluggish
> e.  after 10-15mins of steady cruise car bucks, tach drops to zero, will
> maintain some drivability with held throttle poz.
> f.  a few miles after 1st buck event car dies & won't restart until cool.
> g.  when cool all is fine by cycle is repeatable.
>
> So if someone can reply and let me know whether or not this sounds like
> clogged-cats or something else I'd appreciate it.