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Subject:
Re: EGR Valve on L98
From: "gjt" <gjtooley(at)bellsouth.net>
Subject: Re: EGR Valve on L98
Lines: 62
Date: Sun, 9 Sep 2007 09:46:55 -0500
Bytes: 3808
________________________________________________
Yep, that`s what the guy at Firestone told me. If left alone and not
corrected, the long term effect is loading up the CATs with carbon. He said
the CATS on an L98 are not cheap.
"Butcher" <butcher57(at)swbell.net> wrote in message
news:cuTEi.2105$ZA5.770(at)nlpi068.nbdc.sbc.com...
>
> "Eugene Blanchard" <blanchae(at)telus.net> wrote in message
> news:QhLEi.26498$Pd4.10951(at)edtnps82...
>> My answer is a little bit off topic but it concerns the egr valve. Don`t
>> know where you live but if you don`t have yearly smog tests to pass. I
>> suggest you block off the egr valve.
>>
>> Now I don`t have a 90s Vette but bear with me. On my 92 Ford Ranger, the
>> computer controls the EGR valve position using vacuum, then there`s an
>> EGR
>> position sensor to verify that its working. So disconnecting anything
>> brings up the Check Engine light and a trouble code.
>>
>> To get around the computer, I made a metal plate which matched the
>> outline
>> of the EGR valve gasket and installed it with the gasket. The EGR
>> position
>> sensor reports that the EGR is working and no error codes!
>>
>> Why block off the EGR? It recirculates the exhaust gas back into the
>> intake
>> manifold to reduce NOx emissions. Ideally, you want the coolest air in
>> the
>> intake, the EGR adds extremely HOT exhaust gas in. And it screws up your
>> fuel/air mixture - rather than clean outside air, you have hot CO gas
>> coming back in. The result is less power and poorer gas mileage.
>>
>> Blocking off my EGR valve increased my overall hp (every little bit
>> counts
>> on a 2.3l ford) and increased my gas mileage by 20% around town.
>>
>> http://www.cadvision.com/blanchas/Ranger/egr.html
>>
>> Comments?
>>
>
> Since my LT-4 doesn`t have an EGR valve because of additional cam overlap
> I`m assuming the valve is supposed to close when rpm/throttle increases
> (vacuum decreases, or should I say manifold pressure goes up), so it`s
> `active` only with little or no throttle. And since the ECU controls the
> mixture thinking the EGR is working I`m wondering if the mixture will be
> richer because of the blockoff (instead of just a cooler charge) --
> enriching mixture is usually a good thing for power and throttle off/on
> transition with these newer cars that run so lean, and more power means
> less throttle at any given power setting so mileage would go up a little
> maybe. But what about carbonizing the cat. over time because of the richer
> mixture? Maybe the fix will cause an expensive repair later on if the
> cats. are left in place and block up?
>
> Just a thought...
>
> Butcher
> `96 LT-4 CE
From: "Fixitman" <fixitman333(at)yahoo.com>
Subject: Re: EGR Valve on L98
Lines: 91
Date: Sun, 09 Sep 2007 17:34:21 GMT
Bytes: 4714
________________________________________________
Hmmm.... "badly stuck" can have two very different meanings:
The 1990 Vette has a basic negative backpressure EGR valve. It doesen`t have
an electrical connection, so the ECU cannot directly determine if it is
functioning. The ECU calculates EGR functionality based on changes in sensor
output (knock and O2) when it "expects" the EGR to turn on/off. If it
doesen`t see the change it expects, it will set a code 32 (EGR circuit). If
the EGR is stuck open, it will most likely set a code 45 (Rich exhaust). A
stuck-open EGR will reduce oxygen content in the combustion chamber at all
times though, resulting in poor performance (especially at idle).
basically...
Stuck open = runs bad, code 45 present, CAT damage possible
Stuck closed = runs well, no code 45, CAT damage doubtful
Fixitman
"gjt" <gjtooley(at)bellsouth.net> wrote in message
news:qHTEi.38647$wN3.27074(at)bignews2.bellsouth.net...
> Yep, that`s what the guy at Firestone told me. If left alone and not
> corrected, the long term effect is loading up the CATs with carbon. He
said
> the CATS on an L98 are not cheap.
>
>
> "Butcher" <butcher57(at)swbell.net> wrote in message
> news:cuTEi.2105$ZA5.770(at)nlpi068.nbdc.sbc.com...
> >
> > "Eugene Blanchard" <blanchae(at)telus.net> wrote in message
> > news:QhLEi.26498$Pd4.10951(at)edtnps82...
> >> My answer is a little bit off topic but it concerns the egr valve.
Don`t
> >> know where you live but if you don`t have yearly smog tests to pass. I
> >> suggest you block off the egr valve.
> >>
> >> Now I don`t have a 90s Vette but bear with me. On my 92 Ford Ranger,
the
> >> computer controls the EGR valve position using vacuum, then there`s an
> >> EGR
> >> position sensor to verify that its working. So disconnecting anything
> >> brings up the Check Engine light and a trouble code.
> >>
> >> To get around the computer, I made a metal plate which matched the
> >> outline
> >> of the EGR valve gasket and installed it with the gasket. The EGR
> >> position
> >> sensor reports that the EGR is working and no error codes!
> >>
> >> Why block off the EGR? It recirculates the exhaust gas back into the
> >> intake
> >> manifold to reduce NOx emissions. Ideally, you want the coolest air in
> >> the
> >> intake, the EGR adds extremely HOT exhaust gas in. And it screws up
your
> >> fuel/air mixture - rather than clean outside air, you have hot CO gas
> >> coming back in. The result is less power and poorer gas mileage.
> >>
> >> Blocking off my EGR valve increased my overall hp (every little bit
> >> counts
> >> on a 2.3l ford) and increased my gas mileage by 20% around town.
> >>
> >> http://www.cadvision.com/blanchas/Ranger/egr.html
> >>
> >> Comments?
> >>
> >
> > Since my LT-4 doesn`t have an EGR valve because of additional cam
overlap
> > I`m assuming the valve is supposed to close when rpm/throttle increases
> > (vacuum decreases, or should I say manifold pressure goes up), so it`s
> > `active` only with little or no throttle. And since the ECU controls
the
> > mixture thinking the EGR is working I`m wondering if the mixture will be
> > richer because of the blockoff (instead of just a cooler charge) --
> > enriching mixture is usually a good thing for power and throttle off/on
> > transition with these newer cars that run so lean, and more power means
> > less throttle at any given power setting so mileage would go up a little
> > maybe. But what about carbonizing the cat. over time because of the
richer
> > mixture? Maybe the fix will cause an expensive repair later on if the
> > cats. are left in place and block up?
> >
> > Just a thought...
> >
> > Butcher
> > `96 LT-4 CE
>
>
From: Eugene Blanchard <blanchae(at)telus.net>
Subject: Re: EGR Valve on L98
Lines: 57
Date: Mon, 10 Sep 2007 04:33:21 GMT
NNTP-Posting-Host: 205.206.115.90
Bytes: 3438
________________________________________________
Butcher wrote:
>
> "Eugene Blanchard" <blanchae(at)telus.net> wrote in message
> news:QhLEi.26498$Pd4.10951(at)edtnps82...
>> My answer is a little bit off topic but it concerns the egr valve. Don`t
>> know where you live but if you don`t have yearly smog tests to pass. I
>> suggest you block off the egr valve.
>>
>> Now I don`t have a 90s Vette but bear with me. On my 92 Ford Ranger, the
>> computer controls the EGR valve position using vacuum, then there`s an
>> EGR position sensor to verify that its working. So disconnecting anything
>> brings up the Check Engine light and a trouble code.
>>
>> To get around the computer, I made a metal plate which matched the
>> outline of the EGR valve gasket and installed it with the gasket. The EGR
>> position sensor reports that the EGR is working and no error codes!
>>
>> Why block off the EGR? It recirculates the exhaust gas back into the
>> intake
>> manifold to reduce NOx emissions. Ideally, you want the coolest air in
>> the intake, the EGR adds extremely HOT exhaust gas in. And it screws up
>> your fuel/air mixture - rather than clean outside air, you have hot CO
>> gas coming back in. The result is less power and poorer gas mileage.
>>
>> Blocking off my EGR valve increased my overall hp (every little bit
>> counts on a 2.3l ford) and increased my gas mileage by 20% around town.
>>
>> http://www.cadvision.com/blanchas/Ranger/egr.html
>>
>> Comments?
>>
>
> Since my LT-4 doesn`t have an EGR valve because of additional cam overlap
> I`m assuming the valve is supposed to close when rpm/throttle increases
> (vacuum decreases, or should I say manifold pressure goes up), so it`s
> `active` only with little or no throttle. And since the ECU controls the
> mixture thinking the EGR is working I`m wondering if the mixture will be
> richer because of the blockoff (instead of just a cooler charge) --
> enriching mixture is usually a good thing for power and throttle off/on
> transition with these newer cars that run so lean, and more power means
> less throttle at any given power setting so mileage would go up a little
> maybe. But what about carbonizing the cat. over time because of the richer
> mixture? Maybe the fix will cause an expensive repair later on if the
> cats. are left in place and block up?
>
> Just a thought...
>
> Butcher
> `96 LT-4 CE
You might of guessed it by now, but the cat is long gone...
--
Eugene Blanchard
http://www.cadvision.com/blanchas
Home of the DIY Hot Rod Kustom website
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