Re: CJ8 weber conversion timing/backfire problem
"Dave Milne" wrotE:
> If you tell us when it happens more precisely, should be able to narrow it > down for you. (e.g. at idle / when accelerating / when lifting off ) Under heavy acceleration at higher RPMs when the engine is hot. e.g., I have been driving on the freeway in hot weather for an hour and pull off to an exit ramp and sit at a stop light. The light turns green, I hit the gas hard to get back up to speed quickly, and I let it rev fairly high in gear before up-shifting (so that I can accelerate more quickly.) This is typically the point at which I hear a backfire. > Worst case scenario - backfiring can set fire to your engine bay (blow back > in the carb), blow your exhaust apart or even crack piston rings. You want > to fix it. Ouch, no kidding. If I drive it like granny (no quick acceleration/high RPMs) I seem to avoid backfiring so I can do that until I figure out the bigger problem... but that's just not a fun way to drive. :-) |
Re: CJ8 weber conversion timing/backfire problem
That sounds like an air leak.
You could have a leaky exhaust manifold or a bad EGR valve. My first bet is the exhaust. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Joshua Nelson wrote: > > "Dave Milne" wrotE: > > > If you tell us when it happens more precisely, should be able to narrow it > > down for you. (e.g. at idle / when accelerating / when lifting off ) > > Under heavy acceleration at higher RPMs when the engine is hot. e.g., > I have been driving on the freeway in hot weather for an hour and pull > off to an exit ramp and sit at a stop light. The light turns green, I > hit the gas hard to get back up to speed quickly, and I let it rev > fairly high in gear before up-shifting (so that I can accelerate more > quickly.) This is typically the point at which I hear a backfire. > > > Worst case scenario - backfiring can set fire to your engine bay (blow back > > in the carb), blow your exhaust apart or even crack piston rings. You want > > to fix it. > > Ouch, no kidding. If I drive it like granny (no quick > acceleration/high RPMs) I seem to avoid backfiring so I can do that > until I figure out the bigger problem... but that's just not a fun > way to drive. :-) |
Re: CJ8 weber conversion timing/backfire problem
That sounds like an air leak.
You could have a leaky exhaust manifold or a bad EGR valve. My first bet is the exhaust. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Joshua Nelson wrote: > > "Dave Milne" wrotE: > > > If you tell us when it happens more precisely, should be able to narrow it > > down for you. (e.g. at idle / when accelerating / when lifting off ) > > Under heavy acceleration at higher RPMs when the engine is hot. e.g., > I have been driving on the freeway in hot weather for an hour and pull > off to an exit ramp and sit at a stop light. The light turns green, I > hit the gas hard to get back up to speed quickly, and I let it rev > fairly high in gear before up-shifting (so that I can accelerate more > quickly.) This is typically the point at which I hear a backfire. > > > Worst case scenario - backfiring can set fire to your engine bay (blow back > > in the carb), blow your exhaust apart or even crack piston rings. You want > > to fix it. > > Ouch, no kidding. If I drive it like granny (no quick > acceleration/high RPMs) I seem to avoid backfiring so I can do that > until I figure out the bigger problem... but that's just not a fun > way to drive. :-) |
Re: CJ8 weber conversion timing/backfire problem
Could also be running too lean (intake leak or badly set up carb). Exhaust
runs extra hot as a result and any unburned fuel in the exhaust goes bang. You can see the flames flickering out the back of decelerating touring cars as a rather extreme example. -- Dave Milne, Scotland '99 TJ 4.0 Sahara "Mike Romain" <romainm@sympatico.ca> wrote in message news:3F69E061.6D9C9A09@sympatico.ca... : That sounds like an air leak. : : You could have a leaky exhaust manifold or a bad EGR valve. My first : bet is the exhaust. : : Mike : 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 : 88 Cherokee 235 BFG AT's : : Joshua Nelson wrote: : > : > "Dave Milne" wrotE: : > : > > If you tell us when it happens more precisely, should be able to narrow it : > > down for you. (e.g. at idle / when accelerating / when lifting off ) : > : > Under heavy acceleration at higher RPMs when the engine is hot. e.g., : > I have been driving on the freeway in hot weather for an hour and pull : > off to an exit ramp and sit at a stop light. The light turns green, I : > hit the gas hard to get back up to speed quickly, and I let it rev : > fairly high in gear before up-shifting (so that I can accelerate more : > quickly.) This is typically the point at which I hear a backfire. : > : > > Worst case scenario - backfiring can set fire to your engine bay (blow back : > > in the carb), blow your exhaust apart or even crack piston rings. You want : > > to fix it. : > : > Ouch, no kidding. If I drive it like granny (no quick : > acceleration/high RPMs) I seem to avoid backfiring so I can do that : > until I figure out the bigger problem... but that's just not a fun : > way to drive. :-) |
Re: CJ8 weber conversion timing/backfire problem
Could also be running too lean (intake leak or badly set up carb). Exhaust
runs extra hot as a result and any unburned fuel in the exhaust goes bang. You can see the flames flickering out the back of decelerating touring cars as a rather extreme example. -- Dave Milne, Scotland '99 TJ 4.0 Sahara "Mike Romain" <romainm@sympatico.ca> wrote in message news:3F69E061.6D9C9A09@sympatico.ca... : That sounds like an air leak. : : You could have a leaky exhaust manifold or a bad EGR valve. My first : bet is the exhaust. : : Mike : 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 : 88 Cherokee 235 BFG AT's : : Joshua Nelson wrote: : > : > "Dave Milne" wrotE: : > : > > If you tell us when it happens more precisely, should be able to narrow it : > > down for you. (e.g. at idle / when accelerating / when lifting off ) : > : > Under heavy acceleration at higher RPMs when the engine is hot. e.g., : > I have been driving on the freeway in hot weather for an hour and pull : > off to an exit ramp and sit at a stop light. The light turns green, I : > hit the gas hard to get back up to speed quickly, and I let it rev : > fairly high in gear before up-shifting (so that I can accelerate more : > quickly.) This is typically the point at which I hear a backfire. : > : > > Worst case scenario - backfiring can set fire to your engine bay (blow back : > > in the carb), blow your exhaust apart or even crack piston rings. You want : > > to fix it. : > : > Ouch, no kidding. If I drive it like granny (no quick : > acceleration/high RPMs) I seem to avoid backfiring so I can do that : > until I figure out the bigger problem... but that's just not a fun : > way to drive. :-) |
Re: CJ8 weber conversion timing/backfire problem
Joshua Nelson wrote:
> Cal Wheeler <cal@whee.ler> wrote in message news:<bkb7uo$6o9$2@pita.alt.net>... > >>What kind of "sabbatical" do you call that? > > > > I thought several days off, including a weekend, would be long enough for people to forget how much of a troll and liar you are? |
Re: CJ8 weber conversion timing/backfire problem
Joshua Nelson wrote:
> Cal Wheeler <cal@whee.ler> wrote in message news:<bkb7uo$6o9$2@pita.alt.net>... > >>What kind of "sabbatical" do you call that? > > > > I thought several days off, including a weekend, would be long enough for people to forget how much of a troll and liar you are? |
Re: CJ8 weber conversion timing/backfire problem
Thanks Mike & Dave. It's fuel injected so it's probably not a carb
problem. :-) I will see about getting the exhaust looked at. > > You could have a leaky exhaust manifold or a bad EGR valve. My first > bet is the exhaust. > > Could also be running too lean (intake leak or badly set up carb). Exhaust >runs extra hot as a result and any unburned fuel in the exhaust goes bang. >You can see the flames flickering out the back of decelerating touring cars >as a rather extreme example. |
Re: CJ8 weber conversion timing/backfire problem
Thanks Mike & Dave. It's fuel injected so it's probably not a carb
problem. :-) I will see about getting the exhaust looked at. > > You could have a leaky exhaust manifold or a bad EGR valve. My first > bet is the exhaust. > > Could also be running too lean (intake leak or badly set up carb). Exhaust >runs extra hot as a result and any unburned fuel in the exhaust goes bang. >You can see the flames flickering out the back of decelerating touring cars >as a rather extreme example. |
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