Auto: erratic voltage while accelerating, big drop at idle while stopped

[junior varsity]

Ah.  Good deal.  Will start investigating that route.

[DarkMonster620]

OK ...

Many times, and by experience at the shop, many alternators were replaced and vehicles kept on having the same issue come back until one day I got tired and took my multimeter [I had access to wiring diagrams] and followed the path of electricity, it was all a rusted connection from ECU to 'distribuitor' and since at idle there's just enough voltage to keep the vehicle running with accesories and these 'stole' electricity from the ignition system the vehicle had an erratic idle but above 1000rpm everything was good.

[junior varsity]

Hmmmm..... at the ECU you say....    I will begin stretching / limbering up for any required engine-compartment gymnastics.

[DarkMonster620]

Hmmmm..... at the ECU you say....    I will begin stretching / limbering up for any required engine-compartment gymnastics.

Rmember to fully disconnect the battery ... jic

[junior varsity]

Powermaster Alternator 48202 swapped out with 48237, which is what it 'should have been'..., cleaned the beejeesus out of the throttle body (a drive-by-wire unit), then found a BBK 80mm throttle body for cheap (stock is around 75mm, so barely bigger) and swapped it in, cleaned MAF, discovered a ridiculous amount of carbon and such inside intake manifold attributable to the EGR setup after 220,000mi, so I removed it and blocked off the header and intake port, removed the hose/bracket assembly and the valve itself. I see that it can help reduce pinging at part throttle application, but at the expense of filthing everything up... I understand the principles behind the PCV system, and while I understand the EGR setup, I suppose I reach a different conclusion when I weigh the pro's and con's than the factory did when they made this 5.3L engine.  Apparently a few years later they changed their minds as well and ditched the setup.

Truck ran great today. Will be getting the folks at Black Bear Performance or Wheatley Performance to tune the ECM and remove the EGR trouble code, etc.

Only thing I still wonder is why the needle 'flinches' ever so slightly when the blinker is flashing...  All the previous erratic voltage wobbling has disappeared, so this may be completely normal - I just can't remember what 'normal' looked like anymore!

[DarkMonster620]

jv,

the needle flinching might be a bad ground behind the dash ... Take out and clean with contact cleaner ... This should help

[junior varsity]

nice, will do.