1992 S-10 ignition timing

#11

Steve W. wrote:

Quote:

Ken wrote:
On Feb 18, 11:31 am, E Z Peaces <c... (AT) invalid (DOT) invalid> wrote:

Thanks a lot.

I was wrong in moving the distributor. Yesterday, when the block
temperature was probably below 40F, I had the same problem. The starter
would slow cyclically, as if there was high resistance at one point in
the engine's rotation. As the engine rotated easily with the ignition
disconnected, it seemed that one cylinder was still firing too soon.

I ran the engine a few seconds to back up ten feet. In the next half
hour I started several more times to move the truck a few feet. Each
time, the starter turned the engine normally. The plugs would have been
a little warmer than on my first startup.

I think cold temperatures, compression, and old plugs with big gaps and
rounded electrodes all require more firing voltage. My theory now is
that if the voltage required for a certain plug is high enough, the
spark will jump instead from the rotor to another terminal in the
distributor, causing that other plug to fire on the compression stroke.

Not very likely unless the cap is shot. I have pulled plugs that had the
electrodes burnt off that still fired.

That makes sense in that there's no miss when the engine runs. The cap
was the first thing I looked at, but looking at it wouldn't prove it's
okay. I felt pitting on the rotor, so I'll replace that, too. Maybe a
defective rotor could let the spark jump to the wrong terminal.

#12

Over advanced timing can cause it to bind/lockup during cranking.

On 2/15/2009 3:59 PM, E Z Peaces wrote:

Quote:

A few months ago a neighbor bought a 1992 S-10 with a 4.3L V6. It
cranked fine at first. Later it began hesitating as it was cranked. He
thought it needed a new starter, but it cranks fine if the spark cable
is removed from the distributor.

Once started it seems to run okay. Could the timing be off during
cranking? What could cause this?

#13

Well, I set the timing back. It still has the starting problem when
stone cold, but the owner says it no longer knocks when driving. I
guess it needs tune-up parts.

SnoMan wrote:

Quote:

Over advanced timing can cause it to bind/lockup during cranking.

On 2/15/2009 3:59 PM, E Z Peaces wrote:
A few months ago a neighbor bought a 1992 S-10 with a 4.3L V6. It
cranked fine at first. Later it began hesitating as it was cranked. He
thought it needed a new starter, but it cranks fine if the spark cable
is removed from the distributor.

Once started it seems to run okay. Could the timing be off during
cranking? What could cause this?

#14

By starting problems do you me not lighting off or cranking slow? As far
as knock, the "problem" with those engines is that they never were
design to operate on 87 octane without help because the base compression
ratio is too high for 87. TO make it "tolerate" 87 it uses a generation
two spark knock controller that replaces vacuum advance that can retard
spark up to 20 degrees to limit knock. In doing so performance can
suffer. It is possible that you knock sensor is bad and it is not
retarding spark and with timing is retarded enough to not knock without
active control, performance and starting suffers. I would suggest that
you set base line timing to about 4 degrees BTDC and try a tank of
89/plus and see how it starts and runs. As engine get old they tend to
build up carbon in them that raise CR even more which is good for
efficiency but bad if you feel you must use 87 octane fuel.

On 2/26/2009 9:59 AM, E Z Peaces wrote:

Quote:

Well, I set the timing back. It still has the starting problem when
stone cold, but the owner says it no longer knocks when driving. I guess
it needs tune-up parts.

SnoMan wrote:
Over advanced timing can cause it to bind/lockup during cranking.

On 2/15/2009 3:59 PM, E Z Peaces wrote:
A few months ago a neighbor bought a 1992 S-10 with a 4.3L V6. It
cranked fine at first. Later it began hesitating as it was cranked. He
thought it needed a new starter, but it cranks fine if the spark cable
is removed from the distributor.

Once started it seems to run okay. Could the timing be off during
cranking? What could cause this?

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1992 S-10 ignition timing

4x4 Chevy/GMC Trucks 4x4 Chevy/GMC Trucks Discussions (alt.autos.4x4.chevy-trucks)

Re: 1992 S-10 ignition timing - 02-19-2009 , 08:54 PM

Re: 1992 S-10 ignition timing - 02-25-2009 , 10:26 AM

Re: 1992 S-10 ignition timing - 02-26-2009 , 09:59 AM

Re: 1992 S-10 ignition timing - 02-26-2009 , 12:13 PM