In message <JxX2tWiP5BNp-pn2-NnDw1Qd4X29K@anon.none.net>, "Will Honea" wrote:

>On Tue, 16 Dec 2003 04:29:09 UTC bllsht <nospam@invaliddot.net> wrote:
>
>> In message <151220030900494970%RhmpL33@nospam.net>, "Rich Hampel" wrote:
>>
>> >
>> >Its a @ 2SE (non-Kalyfornia)
>>
>> Good, that eliminates a problem with electronic controls.
>> >
>> >Cam timing is Correct
>>
>> If you say so....
>>
>> >
>> >Yup, I know (now) that changing/replacing intake gaskets has been a
>> >waste of time.
>> >With low vac the engine runs retarded hence rich at normal highway rpm,
>> >at low vac all the dampers in the air cleaner close ... also make it
>> >run rich (but I have them locked out at the moment).
>>
>> Two or three posts have mentioned restricted exhaust now, and you haven't
>> responded to them. Have you checked this? A *symptom* of plugged exhaust would
>> be low vacuum. This would cause a couple of problems.
>>
>> 1) If you can't get the all of the burned gas out, you can't get a full charge
>> of fuel/air in for the next cycle.
>>
>> 2) That vehicle is equipped with a back pressure EGR valve. Too much back
>> pressure could cause too much EGR action. Too much exhaust gas in the
>> combustion chamber displaces too much of the air and fuel needed for decent
>> combustion.
>>
>> Once again, have you checked for restricted exhaust?
>
>Can you put a number on the expected or acceptable back pressure
>(pressure ahead of the cat) for the 4.0 and/or the 2.5? I've seen
>lots of talk about excessive back pressure, but just what constitutes
>excessive??

I don't have a number for it. I don't know if there is one. Most that I see
are pretty obvious just by the symptoms. The marginal ones can be picked up
using a vacuum gauge.

 

In message <JxX2tWiP5BNp-pn2-NnDw1Qd4X29K@anon.none.net>, "Will Honea" wrote:

>On Tue, 16 Dec 2003 04:29:09 UTC bllsht <nospam@invaliddot.net> wrote:
>
>> In message <151220030900494970%RhmpL33@nospam.net>, "Rich Hampel" wrote:
>>
>> >
>> >Its a @ 2SE (non-Kalyfornia)
>>
>> Good, that eliminates a problem with electronic controls.
>> >
>> >Cam timing is Correct
>>
>> If you say so....
>>
>> >
>> >Yup, I know (now) that changing/replacing intake gaskets has been a
>> >waste of time.
>> >With low vac the engine runs retarded hence rich at normal highway rpm,
>> >at low vac all the dampers in the air cleaner close ... also make it
>> >run rich (but I have them locked out at the moment).
>>
>> Two or three posts have mentioned restricted exhaust now, and you haven't
>> responded to them. Have you checked this? A *symptom* of plugged exhaust would
>> be low vacuum. This would cause a couple of problems.
>>
>> 1) If you can't get the all of the burned gas out, you can't get a full charge
>> of fuel/air in for the next cycle.
>>
>> 2) That vehicle is equipped with a back pressure EGR valve. Too much back
>> pressure could cause too much EGR action. Too much exhaust gas in the
>> combustion chamber displaces too much of the air and fuel needed for decent
>> combustion.
>>
>> Once again, have you checked for restricted exhaust?
>
>Can you put a number on the expected or acceptable back pressure
>(pressure ahead of the cat) for the 4.0 and/or the 2.5? I've seen
>lots of talk about excessive back pressure, but just what constitutes
>excessive??

I don't have a number for it. I don't know if there is one. Most that I see
are pretty obvious just by the symptoms. The marginal ones can be picked up
using a vacuum gauge.

 

In message <JxX2tWiP5BNp-pn2-NnDw1Qd4X29K@anon.none.net>, "Will Honea" wrote:

>On Tue, 16 Dec 2003 04:29:09 UTC bllsht <nospam@invaliddot.net> wrote:
>
>> In message <151220030900494970%RhmpL33@nospam.net>, "Rich Hampel" wrote:
>>
>> >
>> >Its a @ 2SE (non-Kalyfornia)
>>
>> Good, that eliminates a problem with electronic controls.
>> >
>> >Cam timing is Correct
>>
>> If you say so....
>>
>> >
>> >Yup, I know (now) that changing/replacing intake gaskets has been a
>> >waste of time.
>> >With low vac the engine runs retarded hence rich at normal highway rpm,
>> >at low vac all the dampers in the air cleaner close ... also make it
>> >run rich (but I have them locked out at the moment).
>>
>> Two or three posts have mentioned restricted exhaust now, and you haven't
>> responded to them. Have you checked this? A *symptom* of plugged exhaust would
>> be low vacuum. This would cause a couple of problems.
>>
>> 1) If you can't get the all of the burned gas out, you can't get a full charge
>> of fuel/air in for the next cycle.
>>
>> 2) That vehicle is equipped with a back pressure EGR valve. Too much back
>> pressure could cause too much EGR action. Too much exhaust gas in the
>> combustion chamber displaces too much of the air and fuel needed for decent
>> combustion.
>>
>> Once again, have you checked for restricted exhaust?
>
>Can you put a number on the expected or acceptable back pressure
>(pressure ahead of the cat) for the 4.0 and/or the 2.5? I've seen
>lots of talk about excessive back pressure, but just what constitutes
>excessive??

I don't have a number for it. I don't know if there is one. Most that I see
are pretty obvious just by the symptoms. The marginal ones can be picked up
using a vacuum gauge.