My truck is coming due for emmisions testing soon so I
thought I'd do the good thing and giver her a tuneup.
So I picked up plugs, wires, cap, and rotor from Toyota
and also adjusted the valves (hot). After doing all of
this she was running great. I also checked the idle HC/CO
with my voltmeter at the check connector, looked good.
I then figured I'd check the
idle speed and timing to make sure it was still within
specs. Idle was a little high but timing was right at 5*
with connector jumpered. I lubed the throttle linkages and
adjusted idle down a bit to make sure it would be within
specs and then went to recheck timing. It was about this
time that I started to notice an intermittent popping from
the muffler and an intermittently rough idle. When I tried
to jumper the check connector and check/reset the timing
the jumper had no effect and the timing was somewhere around
20* BTDC!! WTF happened?! Over the next 2 hours I tried
the following:

1. Disconnect batt. to reset ecu. NO effect.
2. Checked coil for power, primary and secondary resistance
all were within specs.
3. Checked pickup coil resistance. Spec. is 140-180 ohm,
mine is 199 ohm. FSM says replace the distributor, but
it looks like this pickup coil could be replaced by
itself. Any thoughts on this? Could the pickup coil
screw up the timing this bad?
4. Checked air gap on distributor, was within specs.

The only thing left in the FSM to check on the ESA system
is to check the 'IGt' signal from the ECU. It got dark
and I ran out of time tonight. Since the jumper and timing
were working ok previously, the only thing I can figure is
that some electronic part has suddenly decided to crap out
at the worste possible time. Any thoughts on what I may
have screwed up or what I should be checking into would be
much appreciated. This truck has performed flawlessly and
I just took it on a weekend trip over Mt. Hood this past
weekend with not so much as a hicup. I'm very stumped. <img src="/forums/images/graemlins/confused.gif" alt="" />

Regards,
Indy