CJ - backfiring problem help (a little long)
06-12-2006, 11:44 PM
#1
Guest
Posts: n/a
CJ - backfiring problem help (a little long)
My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
4.11's, Detroits, etc and "full" factory emissions crap meaning
computer, pulse air and all those vacuum lines etc (I have one more WA
state emissions test to pass before it "ages out" and it no longer
needs to be tested) is having a mild to severe "backfiring problem"
on deceleration. LOTS of popping and noises out the exhaust when I
decelerate or downshift.
The timing is set at "about 12 degrees" before TDC (which
Chilton's suggests is about right - (pretty sure it's a California
model). The timing mark sorta "bounces around" when I check it
witht the light (distributor vacuum line disconnected and plugged) -
possibly due to some wear in the distributor or ??. I have another
distributor to swap in to "test" the wear theory, but haven't had
the time to do so yet.
Anyway - if I advance the timing further which significantly improves
the driveability and idle, I start to get engine pinging (a little
difficult to hear over the tires) - so I don't really want to leave
it too far advanced. I'm running 87 octane - NOT from Arco.
But I'd like to improve the drive-ability, STOP the "backfiring",
and not damage the engine.
Any thoughts or guidance?
Thanks
Lynn in Vancouver, WA
4.11's, Detroits, etc and "full" factory emissions crap meaning
computer, pulse air and all those vacuum lines etc (I have one more WA
state emissions test to pass before it "ages out" and it no longer
needs to be tested) is having a mild to severe "backfiring problem"
on deceleration. LOTS of popping and noises out the exhaust when I
decelerate or downshift.
The timing is set at "about 12 degrees" before TDC (which
Chilton's suggests is about right - (pretty sure it's a California
model). The timing mark sorta "bounces around" when I check it
witht the light (distributor vacuum line disconnected and plugged) -
possibly due to some wear in the distributor or ??. I have another
distributor to swap in to "test" the wear theory, but haven't had
the time to do so yet.
Anyway - if I advance the timing further which significantly improves
the driveability and idle, I start to get engine pinging (a little
difficult to hear over the tires) - so I don't really want to leave
it too far advanced. I'm running 87 octane - NOT from Arco.
But I'd like to improve the drive-ability, STOP the "backfiring",
and not damage the engine.
Any thoughts or guidance?
Thanks
Lynn in Vancouver, WA
06-13-2006, 12:05 AM
#2
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
That usefully means there's a exhaust gasket or crack leaking
oxygen back into the exhaust. Sometimes disconnecting the Exhaust
Recycling Valve, or Gulp valve will hide a problem in there SMOG
systems.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
oxygen back into the exhaust. Sometimes disconnecting the Exhaust
Recycling Valve, or Gulp valve will hide a problem in there SMOG
systems.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
06-13-2006, 12:05 AM
#3
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
That usefully means there's a exhaust gasket or crack leaking
oxygen back into the exhaust. Sometimes disconnecting the Exhaust
Recycling Valve, or Gulp valve will hide a problem in there SMOG
systems.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
oxygen back into the exhaust. Sometimes disconnecting the Exhaust
Recycling Valve, or Gulp valve will hide a problem in there SMOG
systems.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
06-13-2006, 12:05 AM
#4
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
That usefully means there's a exhaust gasket or crack leaking
oxygen back into the exhaust. Sometimes disconnecting the Exhaust
Recycling Valve, or Gulp valve will hide a problem in there SMOG
systems.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
oxygen back into the exhaust. Sometimes disconnecting the Exhaust
Recycling Valve, or Gulp valve will hide a problem in there SMOG
systems.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
06-13-2006, 10:12 AM
#5
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
I have converted my 86 to a manually tuned engine with about 9 deg
static timing and a ported vacuum advance. Mine pops and burbles when I
decelerate down a steep hill.
If it actually 'backfiring', (firing on the back side of a valve) that
can mean your exhaust and/or intake manifold is loose. This isn't
uncommon. You can test for it by spraying a mist of water along the
seam or carb cleaner or I think even WD40. If any of these make the
engine stumble, then you need to re-torque the intakes back down.
You also could have a broken mechanical timing advance spring or a
seized up advance plate. The advance plate inside the distributor needs
to be lubricated regularly. To do this you pull off the rotor and put
oil on the sponge or felt pad you should find in the center of the
distributor shaft. You then can hand work the advance plate to be sure
it moves freely and springs back hard and fast when released.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
static timing and a ported vacuum advance. Mine pops and burbles when I
decelerate down a steep hill.
If it actually 'backfiring', (firing on the back side of a valve) that
can mean your exhaust and/or intake manifold is loose. This isn't
uncommon. You can test for it by spraying a mist of water along the
seam or carb cleaner or I think even WD40. If any of these make the
engine stumble, then you need to re-torque the intakes back down.
You also could have a broken mechanical timing advance spring or a
seized up advance plate. The advance plate inside the distributor needs
to be lubricated regularly. To do this you pull off the rotor and put
oil on the sponge or felt pad you should find in the center of the
distributor shaft. You then can hand work the advance plate to be sure
it moves freely and springs back hard and fast when released.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
06-13-2006, 10:12 AM
#6
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
I have converted my 86 to a manually tuned engine with about 9 deg
static timing and a ported vacuum advance. Mine pops and burbles when I
decelerate down a steep hill.
If it actually 'backfiring', (firing on the back side of a valve) that
can mean your exhaust and/or intake manifold is loose. This isn't
uncommon. You can test for it by spraying a mist of water along the
seam or carb cleaner or I think even WD40. If any of these make the
engine stumble, then you need to re-torque the intakes back down.
You also could have a broken mechanical timing advance spring or a
seized up advance plate. The advance plate inside the distributor needs
to be lubricated regularly. To do this you pull off the rotor and put
oil on the sponge or felt pad you should find in the center of the
distributor shaft. You then can hand work the advance plate to be sure
it moves freely and springs back hard and fast when released.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
static timing and a ported vacuum advance. Mine pops and burbles when I
decelerate down a steep hill.
If it actually 'backfiring', (firing on the back side of a valve) that
can mean your exhaust and/or intake manifold is loose. This isn't
uncommon. You can test for it by spraying a mist of water along the
seam or carb cleaner or I think even WD40. If any of these make the
engine stumble, then you need to re-torque the intakes back down.
You also could have a broken mechanical timing advance spring or a
seized up advance plate. The advance plate inside the distributor needs
to be lubricated regularly. To do this you pull off the rotor and put
oil on the sponge or felt pad you should find in the center of the
distributor shaft. You then can hand work the advance plate to be sure
it moves freely and springs back hard and fast when released.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
06-13-2006, 10:12 AM
#7
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
I have converted my 86 to a manually tuned engine with about 9 deg
static timing and a ported vacuum advance. Mine pops and burbles when I
decelerate down a steep hill.
If it actually 'backfiring', (firing on the back side of a valve) that
can mean your exhaust and/or intake manifold is loose. This isn't
uncommon. You can test for it by spraying a mist of water along the
seam or carb cleaner or I think even WD40. If any of these make the
engine stumble, then you need to re-torque the intakes back down.
You also could have a broken mechanical timing advance spring or a
seized up advance plate. The advance plate inside the distributor needs
to be lubricated regularly. To do this you pull off the rotor and put
oil on the sponge or felt pad you should find in the center of the
distributor shaft. You then can hand work the advance plate to be sure
it moves freely and springs back hard and fast when released.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
static timing and a ported vacuum advance. Mine pops and burbles when I
decelerate down a steep hill.
If it actually 'backfiring', (firing on the back side of a valve) that
can mean your exhaust and/or intake manifold is loose. This isn't
uncommon. You can test for it by spraying a mist of water along the
seam or carb cleaner or I think even WD40. If any of these make the
engine stumble, then you need to re-torque the intakes back down.
You also could have a broken mechanical timing advance spring or a
seized up advance plate. The advance plate inside the distributor needs
to be lubricated regularly. To do this you pull off the rotor and put
oil on the sponge or felt pad you should find in the center of the
distributor shaft. You then can hand work the advance plate to be sure
it moves freely and springs back hard and fast when released.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"lynnhowlyn@aol.com" wrote:
>
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
06-13-2006, 10:42 AM
#8
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
The most common cause for backfiring on deceleration is idle mixture too
lean. That could be a vacuum leak with this vintage. They really do have
too many vacuum lines, don't they? If that is not it, then short of a new
or rebuilt carburetor, I don't know how you get a proper idle mixture. With
older models you simply back off the idle mixture screw, until the engine is
getting a rich enough mixture. With the smog controlled models, there is
usually something to prevent that.
Mike and Bill have some good ideas too. Just don't take either of those
guys too seriously. They are pretty old and grizzled, both of them. ;^)
Earle
<lynnhowlyn@aol.com> wrote in message
news:1150170260.713493.323610@y43g2000cwc.googlegr oups.com...
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
>
--
Posted via a free Usenet account from http://www.teranews.com
lean. That could be a vacuum leak with this vintage. They really do have
too many vacuum lines, don't they? If that is not it, then short of a new
or rebuilt carburetor, I don't know how you get a proper idle mixture. With
older models you simply back off the idle mixture screw, until the engine is
getting a rich enough mixture. With the smog controlled models, there is
usually something to prevent that.
Mike and Bill have some good ideas too. Just don't take either of those
guys too seriously. They are pretty old and grizzled, both of them. ;^)
Earle
<lynnhowlyn@aol.com> wrote in message
news:1150170260.713493.323610@y43g2000cwc.googlegr oups.com...
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
>
--
Posted via a free Usenet account from http://www.teranews.com
06-13-2006, 10:42 AM
#9
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
The most common cause for backfiring on deceleration is idle mixture too
lean. That could be a vacuum leak with this vintage. They really do have
too many vacuum lines, don't they? If that is not it, then short of a new
or rebuilt carburetor, I don't know how you get a proper idle mixture. With
older models you simply back off the idle mixture screw, until the engine is
getting a rich enough mixture. With the smog controlled models, there is
usually something to prevent that.
Mike and Bill have some good ideas too. Just don't take either of those
guys too seriously. They are pretty old and grizzled, both of them. ;^)
Earle
<lynnhowlyn@aol.com> wrote in message
news:1150170260.713493.323610@y43g2000cwc.googlegr oups.com...
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
>
--
Posted via a free Usenet account from http://www.teranews.com
lean. That could be a vacuum leak with this vintage. They really do have
too many vacuum lines, don't they? If that is not it, then short of a new
or rebuilt carburetor, I don't know how you get a proper idle mixture. With
older models you simply back off the idle mixture screw, until the engine is
getting a rich enough mixture. With the smog controlled models, there is
usually something to prevent that.
Mike and Bill have some good ideas too. Just don't take either of those
guys too seriously. They are pretty old and grizzled, both of them. ;^)
Earle
<lynnhowlyn@aol.com> wrote in message
news:1150170260.713493.323610@y43g2000cwc.googlegr oups.com...
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
>
--
Posted via a free Usenet account from http://www.teranews.com
06-13-2006, 10:42 AM
#10
Guest
Posts: n/a
Re: CJ - backfiring problem help (a little long)
The most common cause for backfiring on deceleration is idle mixture too
lean. That could be a vacuum leak with this vintage. They really do have
too many vacuum lines, don't they? If that is not it, then short of a new
or rebuilt carburetor, I don't know how you get a proper idle mixture. With
older models you simply back off the idle mixture screw, until the engine is
getting a rich enough mixture. With the smog controlled models, there is
usually something to prevent that.
Mike and Bill have some good ideas too. Just don't take either of those
guys too seriously. They are pretty old and grizzled, both of them. ;^)
Earle
<lynnhowlyn@aol.com> wrote in message
news:1150170260.713493.323610@y43g2000cwc.googlegr oups.com...
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
>
--
Posted via a free Usenet account from http://www.teranews.com
lean. That could be a vacuum leak with this vintage. They really do have
too many vacuum lines, don't they? If that is not it, then short of a new
or rebuilt carburetor, I don't know how you get a proper idle mixture. With
older models you simply back off the idle mixture screw, until the engine is
getting a rich enough mixture. With the smog controlled models, there is
usually something to prevent that.
Mike and Bill have some good ideas too. Just don't take either of those
guys too seriously. They are pretty old and grizzled, both of them. ;^)
Earle
<lynnhowlyn@aol.com> wrote in message
news:1150170260.713493.323610@y43g2000cwc.googlegr oups.com...
> My 83 CJ7 with a stock (so far as I know) 258, T176, D300, 33's,
> 4.11's, Detroits, etc and "full" factory emissions crap meaning
> computer, pulse air and all those vacuum lines etc (I have one more WA
> state emissions test to pass before it "ages out" and it no longer
> needs to be tested) is having a mild to severe "backfiring problem"
> on deceleration. LOTS of popping and noises out the exhaust when I
> decelerate or downshift.
>
> The timing is set at "about 12 degrees" before TDC (which
> Chilton's suggests is about right - (pretty sure it's a California
> model). The timing mark sorta "bounces around" when I check it
> witht the light (distributor vacuum line disconnected and plugged) -
> possibly due to some wear in the distributor or ??. I have another
> distributor to swap in to "test" the wear theory, but haven't had
> the time to do so yet.
>
> Anyway - if I advance the timing further which significantly improves
> the driveability and idle, I start to get engine pinging (a little
> difficult to hear over the tires) - so I don't really want to leave
> it too far advanced. I'm running 87 octane - NOT from Arco.
>
> But I'd like to improve the drive-ability, STOP the "backfiring",
> and not damage the engine.
>
> Any thoughts or guidance?
>
> Thanks
>
> Lynn in Vancouver, WA
>
--
Posted via a free Usenet account from http://www.teranews.com
