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-   -   4.0 running weak (https://www.jeepscanada.com/jeep-mailing-list-32/4-0-running-weak-8206/)

Lee Ayrton Dec 1, 2003 01:01 PM

Re: 4.0 running weak
 
On or about 1 Dec 2003, Dalewhite of dalewhite@aol.com wrote:

> The engine runs smoothly with no missing. When "stepping on it" at
> moderate RPM's it just "wilts", acting like it is getting too much or
> not enough gas. I will add that I have an Avenger supercharger
> installed but I believe my problems are not associated with that.


This is way out of my area, but perhaps it will help: I was just reading
some old reviews and one article was on an aftermarket turbocharger kit
developed for Jeeps (during the 1970s "oil crisis"). The article spent
quite a bit of time on just the symptom you describe above. In this case
it was the accelerator pump delivering far too much gas for the engine to
handle.




Lee Ayrton Dec 1, 2003 01:01 PM

Re: 4.0 running weak
 
On or about 1 Dec 2003, Dalewhite of dalewhite@aol.com wrote:

> The engine runs smoothly with no missing. When "stepping on it" at
> moderate RPM's it just "wilts", acting like it is getting too much or
> not enough gas. I will add that I have an Avenger supercharger
> installed but I believe my problems are not associated with that.


This is way out of my area, but perhaps it will help: I was just reading
some old reviews and one article was on an aftermarket turbocharger kit
developed for Jeeps (during the 1970s "oil crisis"). The article spent
quite a bit of time on just the symptom you describe above. In this case
it was the accelerator pump delivering far too much gas for the engine to
handle.




Lee Ayrton Dec 1, 2003 01:01 PM

Re: 4.0 running weak
 
On or about 1 Dec 2003, Dalewhite of dalewhite@aol.com wrote:

> The engine runs smoothly with no missing. When "stepping on it" at
> moderate RPM's it just "wilts", acting like it is getting too much or
> not enough gas. I will add that I have an Avenger supercharger
> installed but I believe my problems are not associated with that.


This is way out of my area, but perhaps it will help: I was just reading
some old reviews and one article was on an aftermarket turbocharger kit
developed for Jeeps (during the 1970s "oil crisis"). The article spent
quite a bit of time on just the symptom you describe above. In this case
it was the accelerator pump delivering far too much gas for the engine to
handle.




Kevin in San Diego Dec 2, 2003 03:23 AM

Re: 4.0 running weak
 
What area of the country do you live in. Maybe the group can send you to
someone who knows what the heck they are doing.
KH

"Dalewhite" <dalewhite@aol.com> wrote in message
news:20031201093115.08153.00000859@mb-m03.aol.com...
> The CPS (Advance Adapters) is mounted on the front of the engine. It is
> positioned per AA instructions. I took the rig to a hot rod shop in

Phoenix.
> 4 hours of tweaking and trying different settings only produced worse

results.
> The diagnostic reader showed the timing to be "off" but setting it to

spec.
> caused the engine to run much worse. One of their last exercises was to
> install a pressure guage on the exhaust pipe ahead of the cat. conv. it

showed
> approx. 5=6 lb. of back pressure at 4k rpm. Then they said I must have an
> obstruction in the exhaust line as I should show no more than 2-3 lb of

back
> pressure and that must be the cause of the problem.
> So I went home, took the cat. conv. off and replace it with t straight

pipe.
> The cat showed no apparent problem. The car runs just the same. The

exhaust
> muffller is a Borla and I have not disturbed it.
> The engine runs smoothly with no missing. When "stepping on it" at

moderate
> RPM's it just "wilts", acting like it is getting too much or not enough

gas. I
> will add that I have an Avenger supercharger installed but I believe my
> problems are not associated with that.
> Thank you for your feedback.




Kevin in San Diego Dec 2, 2003 03:23 AM

Re: 4.0 running weak
 
What area of the country do you live in. Maybe the group can send you to
someone who knows what the heck they are doing.
KH

"Dalewhite" <dalewhite@aol.com> wrote in message
news:20031201093115.08153.00000859@mb-m03.aol.com...
> The CPS (Advance Adapters) is mounted on the front of the engine. It is
> positioned per AA instructions. I took the rig to a hot rod shop in

Phoenix.
> 4 hours of tweaking and trying different settings only produced worse

results.
> The diagnostic reader showed the timing to be "off" but setting it to

spec.
> caused the engine to run much worse. One of their last exercises was to
> install a pressure guage on the exhaust pipe ahead of the cat. conv. it

showed
> approx. 5=6 lb. of back pressure at 4k rpm. Then they said I must have an
> obstruction in the exhaust line as I should show no more than 2-3 lb of

back
> pressure and that must be the cause of the problem.
> So I went home, took the cat. conv. off and replace it with t straight

pipe.
> The cat showed no apparent problem. The car runs just the same. The

exhaust
> muffller is a Borla and I have not disturbed it.
> The engine runs smoothly with no missing. When "stepping on it" at

moderate
> RPM's it just "wilts", acting like it is getting too much or not enough

gas. I
> will add that I have an Avenger supercharger installed but I believe my
> problems are not associated with that.
> Thank you for your feedback.




Kevin in San Diego Dec 2, 2003 03:23 AM

Re: 4.0 running weak
 
What area of the country do you live in. Maybe the group can send you to
someone who knows what the heck they are doing.
KH

"Dalewhite" <dalewhite@aol.com> wrote in message
news:20031201093115.08153.00000859@mb-m03.aol.com...
> The CPS (Advance Adapters) is mounted on the front of the engine. It is
> positioned per AA instructions. I took the rig to a hot rod shop in

Phoenix.
> 4 hours of tweaking and trying different settings only produced worse

results.
> The diagnostic reader showed the timing to be "off" but setting it to

spec.
> caused the engine to run much worse. One of their last exercises was to
> install a pressure guage on the exhaust pipe ahead of the cat. conv. it

showed
> approx. 5=6 lb. of back pressure at 4k rpm. Then they said I must have an
> obstruction in the exhaust line as I should show no more than 2-3 lb of

back
> pressure and that must be the cause of the problem.
> So I went home, took the cat. conv. off and replace it with t straight

pipe.
> The cat showed no apparent problem. The car runs just the same. The

exhaust
> muffller is a Borla and I have not disturbed it.
> The engine runs smoothly with no missing. When "stepping on it" at

moderate
> RPM's it just "wilts", acting like it is getting too much or not enough

gas. I
> will add that I have an Avenger supercharger installed but I believe my
> problems are not associated with that.
> Thank you for your feedback.




Simon Juncal Dec 2, 2003 10:55 PM

Re: 4.0 running weak
 


Dalewhite wrote:
> The engine runs smoothly with no missing. When "stepping on it" at
> moderate RPM's it just "wilts", acting like it is getting too much or
> not enough gas.


Perhaps it's not just "acting" like it.

> I will add that I have an Avenger supercharger installed but I
> believe my problems are not associated with that. Thank you for your


Why do you believe that? No offense but you haven't given us much to go
on. Do you still have stock injectors? If you upgraded injectors did you
also upgrade the fuel pump? Have you changed the fuel filter?

Did the same shop that told you about the back pressure install the SC,
injectors and higher volume fuel pump/regulator?

As for the symptoms when did they show up (safe to assume they didn't
show up right after the SC was put on?) How many miles do you have on it?


Simon Juncal Dec 2, 2003 10:55 PM

Re: 4.0 running weak
 


Dalewhite wrote:
> The engine runs smoothly with no missing. When "stepping on it" at
> moderate RPM's it just "wilts", acting like it is getting too much or
> not enough gas.


Perhaps it's not just "acting" like it.

> I will add that I have an Avenger supercharger installed but I
> believe my problems are not associated with that. Thank you for your


Why do you believe that? No offense but you haven't given us much to go
on. Do you still have stock injectors? If you upgraded injectors did you
also upgrade the fuel pump? Have you changed the fuel filter?

Did the same shop that told you about the back pressure install the SC,
injectors and higher volume fuel pump/regulator?

As for the symptoms when did they show up (safe to assume they didn't
show up right after the SC was put on?) How many miles do you have on it?


Simon Juncal Dec 2, 2003 10:55 PM

Re: 4.0 running weak
 


Dalewhite wrote:
> The engine runs smoothly with no missing. When "stepping on it" at
> moderate RPM's it just "wilts", acting like it is getting too much or
> not enough gas.


Perhaps it's not just "acting" like it.

> I will add that I have an Avenger supercharger installed but I
> believe my problems are not associated with that. Thank you for your


Why do you believe that? No offense but you haven't given us much to go
on. Do you still have stock injectors? If you upgraded injectors did you
also upgrade the fuel pump? Have you changed the fuel filter?

Did the same shop that told you about the back pressure install the SC,
injectors and higher volume fuel pump/regulator?

As for the symptoms when did they show up (safe to assume they didn't
show up right after the SC was put on?) How many miles do you have on it?



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