'96 LHS cats

Mike Easter wrote:

>
> I'm thinking that if the same engine didn't even have a 3rd cat, with my
> brand new rear cat taking care of a little weakness in one of the front
> cats, I'll probably be OK anyway.
>
>
>

Not if the front cats are reduction catalysts and the rear cat is the
oxidation catalyst.... if so then all 3 need to work. I'm not sure how
the 96 LH is set up in that regard.

But you're still HEAVILY speculating. Cats rarely fail, CELs are almost
always set by some other problem throwing the O2 readings out of balance.

Steve wrote:
> Mike Easter wrote:
>> MoPar Man wrote:
>>
>> Thanks for your input.
>>
>>> Mike Easter wrote:
>>>
>>>> I have a 96 Chrys LHS. Its catalytic converters are 3, one for
>>>> each exhaust manifold/bank and one central behind those.
>>
>>> I've been told that the catalytic convertor units (left and right) are
>>> very expensive. Are you sure that your's is defective?
>>
>> It passed CA smog check 1 year ago. Recently the check engine light
>> came on which 'suggested' the R cat's function. A friend with some
>> experience had a computer that allowed us/him (I was confused by the
>> dynamic readout) to look at the upstream and downstream O2 levels
>> comparing one side to the other. If people like to think of cats as
>> getting 'tired', I suppose that was the idea he was trying to get
>> across. He turned off the check engine light and I'm waiting to see
>> if it comes back on now.
>
>
> Its much more probable that what is getting "tired" is either the
> upstream or downstream O2 sensor that is then giving false erroneous
> readings to the engine management system. Either that or another engine
> management problem like a leaky injector causing an excessively low O2
> reading on one bank but not the other, or an intake leak causing a high
> O2 reading on one bank but not the other. Those upstream cats very
> rarely fail on LH cars, unless there's a catastrophic problem like a
> badly leaking fuel injector or an un-treated misfire that causes a
> severe overheat.

Ah, so. Perhaps it needs more accurate diagnostics than he was using.
Those O2 levels upstream and downstream were all over the map on both
sides to my untrained eye.


--
Mike Easter

Steve wrote:
> Mike Easter wrote:
>
>>
>> I'm thinking that if the same engine didn't even have a 3rd cat, with
>> my brand new rear cat taking care of a little weakness in one of the
>> front cats, I'll probably be OK anyway.
>>
>>
>>
>
> Not if the front cats are reduction catalysts and the rear cat is the
> oxidation catalyst.... if so then all 3 need to work. I'm not sure how
> the 96 LH is set up in that regard.
>
> But you're still HEAVILY speculating. Cats rarely fail, CELs are almost
> always set by some other problem throwing the O2 readings out of
> balance.

This is 3 days later and I'm still waiting for the light to come back on.

--
Mike Easter

Mike,

If it does, make sure it isn't just the O2 sensor... A much simpler and
cheaper fix.

Bob

"Mike Easter" > wrote in message
...
> Steve wrote:
>> Mike Easter wrote:
>>
>>>
>>> I'm thinking that if the same engine didn't even have a 3rd cat, with
>>> my brand new rear cat taking care of a little weakness in one of the
>>> front cats, I'll probably be OK anyway.
>>>
>>>
>>>
>>
>> Not if the front cats are reduction catalysts and the rear cat is the
>> oxidation catalyst.... if so then all 3 need to work. I'm not sure how
>> the 96 LH is set up in that regard.
>>
>> But you're still HEAVILY speculating. Cats rarely fail, CELs are almost
>> always set by some other problem throwing the O2 readings out of
>> balance.
>
> This is 3 days later and I'm still waiting for the light to come back on.
>
> --
> Mike Easter

the rear cat is the reduction cat, the post cat o2 sensors are always behind
the ox cat.
"Mike Easter" > wrote in message
...
> MoPar Man wrote:
>
>> Also, are there any sensors in the exhaust stream? If so, where?
>> Before, or after, the cats ?
>
> There are sensors before and after both L & R cats. Then later comes the
> middle/rear cat.
>
> The before L&R cat sensors are best seen/found from the engine compartment
> not far past the manifolds, the after L&R cats from underneath not far
> forward of the mid/rear cat.
>
> I had occasion to see all of those sensor connxns Friday.
>
>
> --
> Mike Easter
>

If you do replace O2 sensors, do *not* use Bosch sensors - they do not
work on the LH cars.

--
Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')


Bob Shuman wrote:
> Mike,
>
> If it does, make sure it isn't just the O2 sensor... A much simpler and
> cheaper fix.
>
> Bob
>
> "Mike Easter" > wrote in message
> ...
>> Steve wrote:
>>> Mike Easter wrote:
>>>
>>>> I'm thinking that if the same engine didn't even have a 3rd cat, with
>>>> my brand new rear cat taking care of a little weakness in one of the
>>>> front cats, I'll probably be OK anyway.
>>>>
>>>>
>>>>
>>> Not if the front cats are reduction catalysts and the rear cat is the
>>> oxidation catalyst.... if so then all 3 need to work. I'm not sure how
>>> the 96 LH is set up in that regard.
>>>
>>> But you're still HEAVILY speculating. Cats rarely fail, CELs are almost
>>> always set by some other problem throwing the O2 readings out of
>>> balance.
>> This is 3 days later and I'm still waiting for the light to come back on.
>>
>> --
>> Mike Easter
>
>