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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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