failed emissions, jr/sc?

hi,

yes connecticut once again has an emission program and my 95 miata
failed w/ high hydrocarbons, (185 vs a pass @ 167). i am wondering if
this is due to the fact that the jr supercharger on the car froze an
idler wheel and shortly there after the belt. i have ordered both parts
and i am wondering if this is the only issue or if i should check for
something else. btw: car has 97k on the clock and a resent valve job.
thanks,
peter

picaza wrote:
> hi,
>
> yes connecticut once again has an emission program and my 95 miata
> failed w/ high hydrocarbons, (185 vs a pass @ 167). i am wondering if
> this is due to the fact that the jr supercharger on the car froze an
> idler wheel and shortly there after the belt. i have ordered both parts
> and i am wondering if this is the only issue or if i should check for
> something else.

Well, if your S/C nose pulley isn't spinning - and it won't be
without a belt on it - then you're not getting any boost. With
no boost, you're in bypass mode all the time (assuming your bypass
valve and actuator are working correctly) and should not be seeing
any fuel enrichment at all. My experience is limited to the NB system
which uses the JR Powercard for fuel enrichment - this system would
not be running rich under these conditions.

However, I do not know the tricks used for fuel management on the
older systems, which relied on manipulating sensor signals. I suppose
it's possible that you could be seeing a problem if your bypass assembly
isn't working correctly but that's just speculation, and I suspect that
you'd be way down on power if the bypass valve wasn't in bypass mode.

So - assuming your bypass assembly is working correctly and your sensors
are correctly connected, which are probably both true, you've just
failed a test by being slightly over the limit. It could be a catalytic
converter issue or ?

So I think you should check for something.

Dana

"Dana H. Myers" > wrote:

>picaza wrote:
>> hi,
>>
>> yes connecticut once again has an emission program and my 95 miata
>> failed w/ high hydrocarbons, (185 vs a pass @ 167). i am wondering if
>> this is due to the fact that the jr supercharger on the car froze an
>> idler wheel and shortly there after the belt. i have ordered both parts
>> and i am wondering if this is the only issue or if i should check for
>> something else.
>
>Well, if your S/C nose pulley isn't spinning - and it won't be
>without a belt on it - then you're not getting any boost. With
>no boost, you're in bypass mode all the time (assuming your bypass
>valve and actuator are working correctly) and should not be seeing
>any fuel enrichment at all. My experience is limited to the NB system
>which uses the JR Powercard for fuel enrichment - this system would
>not be running rich under these conditions.
>
>However, I do not know the tricks used for fuel management on the
>older systems, which relied on manipulating sensor signals. I suppose
>it's possible that you could be seeing a problem if your bypass assembly
>isn't working correctly but that's just speculation, and I suspect that
>you'd be way down on power if the bypass valve wasn't in bypass mode.
>
>So - assuming your bypass assembly is working correctly and your sensors
>are correctly connected, which are probably both true, you've just
>failed a test by being slightly over the limit. It could be a catalytic
>converter issue or ?

I would think the settings JR devised to get through CARB clearing
might not work as well if the SC is not acting normally. JR is trying
to trick the ECU in delivering too much HC (gas). I would replace
belt and idler pulley, retest, and take it from there.

Leon

--
Leon van Dommelen Bozo, the White 96 Sebring Miata .)
http://www.dommelen.net/miata
EXIT THE INTERSTATES (Jamie Jensen)

Leon van Dommelen wrote:
> "Dana H. Myers" > wrote:

>>So - assuming your bypass assembly is working correctly and your sensors
>>are correctly connected, which are probably both true, you've just
>>failed a test by being slightly over the limit. It could be a catalytic
>>converter issue or ?
>
>
> I would think the settings JR devised to get through CARB clearing
> might not work as well if the SC is not acting normally. JR is trying
> to trick the ECU in delivering too much HC (gas). I would replace
> belt and idler pulley, retest, and take it from there.

If the s/c isn't generating boost and is bypassed, I'd rather expect
the fuel delivery to be about normal - regardless of the reason
why the S/C is bypassed. It seems it would need to be this way
for emissions approval in the first place. So, while your advice
is obviously sound, I tend to believe that the original poster
needs to prepare himself for the chance of replacing the O2 sensor
and/or the catalytic converter.

Of course, we're just guessing from a description in
a Usenet message ;-)

Dana

"Dana H. Myers" > wrote:

>Leon van Dommelen wrote:
>> "Dana H. Myers" > wrote:
>
>>>So - assuming your bypass assembly is working correctly and your sensors
>>>are correctly connected, which are probably both true, you've just
>>>failed a test by being slightly over the limit. It could be a catalytic
>>>converter issue or ?
>>
>>
>> I would think the settings JR devised to get through CARB clearing
>> might not work as well if the SC is not acting normally. JR is trying
>> to trick the ECU in delivering too much HC (gas). I would replace
>> belt and idler pulley, retest, and take it from there.
>
>If the s/c isn't generating boost and is bypassed, I'd rather expect
>the fuel delivery to be about normal - regardless of the reason
>why the S/C is bypassed.

No. The ECU is tricked into thinking that the air that is coming
through is at -40 C, hence dense, causing it to deliver more fuel
than it should.

> It seems it would need to be this way
>for emissions approval in the first place. So, while your advice
>is obviously sound, I tend to believe that the original poster
>needs to prepare himself for the chance of replacing the O2 sensor
>and/or the catalytic converter.

You are probably right here anyway. They both have obviously
seen a lot of abuse.

Leon

>Of course, we're just guessing from a description in
>a Usenet message ;-)
>
>Dana

--
Leon van Dommelen Bozo, the White 96 Sebring Miata .)
http://www.dommelen.net/miata
EXIT THE INTERSTATES (Jamie Jensen)