:
: Well I haven't post here before, but from
: reading some of the posts I can see there
: are some knowledgeable folks here so I am
: asking if anyone can shed some light on my
: problem.
:
: Several days ago my 86 started to idle weird,
: fast, slow, almost stall, then OK, then the
: same thing again. And backing off down a
: long hill would cause back fireing in the
: exhaust. I don't run a muffler, just the cat
: converter makes it quiet enough, so
: backfires are noticable. The last day or so
: it is running fine again. However it won't
: ping normally. Usually, with the timming set
: where I have it, it will ping going up a
: hill if I don't shift and keep it running at
: a reasonable rpm. And after an oil change
: today and just looking around it seems the
: exhaust pipe looks to be rich, that is
: black. Could be from idleing after the oil
: change, but I don't think so, don't remember
: black there. Maybe it is running rich?
: Therefore no, or much less tendency to ping?
: Could the timming be retarded? This is what
: I thought till I say the exhaust. However it
: has normal power, and seems to run normally
: except for the change in the
: "ping". Anyone got any ideas. Sure
: would appreciate a tip or two. This thing
: isn't like the old ones.
:
: Thanks, Tom

: well, i had a problem similar to this, first
: off has the timing chain ever been repaced,
: that'd be my #1 guess, and the carb rebuild
: and full tuneup would be my next best guess
: (any signs of flooding when the idle
: dropes?? how do the plugs look?? do you hear
: poping noises from the exhaust?? could be
: missing on a cylender check the most basic
: things and work your way up from there
:
: Justin

:
: Well the timming chain isn't new, the engine
: has only 170,000 on it, I have had them last
: a lot longer, Don't think it is that anyway,
: runs too good now for that. Still have black
: exhaust pipe, but is running well today, no
: pinging still. Carb hasn't been ribuilt,
: that is a possibility. It could have been
: flooding when it was nearly stalling from
: low speed. Other parts, wires, plugs, cap
: and rotor not new but not that old.
: Thanks for responding.

: An 86 what? Truck?
: When my slant 6s have weird idle problems,
: often it is just the nuts are loose that
: hold the carburetor to the manifold.

: Well I haven't post here before, but from
: reading some of the posts I can see there
: are some knowledgeable folks here so I am
: asking if anyone can shed some light on my
: problem.
:
: Several days ago my 86 started to idle weird,
: fast, slow, almost stall, then OK, then the
: same thing again. And backing off down a
: long hill would cause back fireing in the
: exhaust. I don't run a muffler, just the cat
: converter makes it quiet enough, so
: backfires are noticable. The last day or so
: it is running fine again. However it won't
: ping normally. Usually, with the timming set
: where I have it, it will ping going up a
: hill if I don't shift and keep it running at
: a reasonable rpm. And after an oil change
: today and just looking around it seems the
: exhaust pipe looks to be rich, that is
: black. Could be from idleing after the oil
: change, but I don't think so, don't remember
: black there. Maybe it is running rich?
: Therefore no, or much less tendency to ping?
: Could the timming be retarded? This is what
: I thought till I say the exhaust. However it
: has normal power, and seems to run normally
: except for the change in the
: "ping". Anyone got any ideas. Sure
: would appreciate a tip or two. This thing
: isn't like the old ones.
: Thanks, Tom

: It could have something to do with the EGR
: valve, see if that is operating correctly
: and that the passageway is clear.
: I am a bet "weak" on these, are there
: any feed-back sensors that help the computer
: adjust mixture? (temp or O2 sensor?)
:
: I know that's not much to go on but just some
: ideas on possible places to look.
: DD

: Believe it or not I've had a sticking PCV valve
: cause these same symptoms. After pulling my
: hair out it was a $5.00 PCV valve.

:
: It could have something to do with the EGR
: valve, see if that is operating correctly
: and that the passageway is clear.
: I am a bet "weak" on these, are there
: any feed-back sensors that help the computer
: adjust mixture? (temp or O2 sensor?)
:
: I know that's not much to go on but just some
: ideas on possible places to look.
: DD

: One more thing to check for. Is it automatic or
: manual transmission? The Auto trans trucks
: have two pick-up coils in the distributor.