vehicle - 83 LG4 w/CCC Q-Jet, 700r4. - 119,xxx miles, no smog pump, no egr, all missing vac lines capped off. MSD OE style cap/rotor/coil/wires

I've been dealing with drivability issues this summer involving ethanol/non-ethanol fuels. I think I have that figured out by running 89 octane 5% Ethanol. One problem I can't solve is if I come to a stop sorta quickly, the voltage drops down to below 12v and the car will try to stall out. what I have to do is slow down early, and shift into neutral to rev the engine up to keep the voltage up to atleast 13v. I've tested the electrical system twice in the past 3 weeks and the battery, alternator and starter all check out fine. The CEL came on for a code 44 so I swapped out the oxygen sensor and fuel filter one at a time to see if that helped.. I have also dumped various additives ( seafoam, lucas ethanol treatment, etc) in the fuel system to help with the problem and nothing has really fixed it. One thing I haven't done is changed the spark plugs. They have been in the car for a atleast 5 years, but the car hasn't been driven much in that time frame.

I know it's hard to diagnose something via the internet, but does anyone have any idea what else it could be?

 

you have some bad electrical connection(s)-especially check the battery cables,the cable connections at the starter motor,ground cable connection to engine,and engine to body ground strap.

 

Even if alternator output dropped to 6V, shouldn't a GOOD battery keep the car running at a stop? My first car as a kid, '70 Duster with slant 6 and 36A alternator, would regularly discharge at an idle. This was normal and expected. It simply did not put out enough amps at 600 or so RPM to supply the ignition, headlamps, marker lamps, dash lamps, radio, etc. You could see the headlamps dim to the beat of the music! But it never caused a stalling problem.

Sounds to me like you have another drive-ability issue. As the engine is choking coming to a stop, with low RPM, yes the alternator output will drop. But that's a result, not the cause.

 

One thing I forgot to mention is the oe alternator was replaced a couple years ago with a reman'ed unit from the local big box parts store. Is it possible that the alternator is not putting out enough amps even if it tests good voltage wise?

I haven't had a chance to check anything else out in the past couple days. the frustrating part is the wiring is stock and has not been hacked. the only thing not original is the battery and the alternator.

 

It's worth having them test for.

If I recall correctly, the computers would shut down at around 9V, so if it's dipping too low, that could be your issue.

 

So it's been a week or two and I think I may have figured out what it was.

Two weeks ago I spent a few minutes cleaning the battery terminals and the one ground on the passenger side fender. there was hardly any corrosion, but it didn't hurt to clean them up. took it for a drive and no change. Ok, back to the drawing board.

this past week I was at walmart and figured I'd try something. I grabbed a 8oz bottle of StarTron and dumped it in the tank with about a 1/4 tank of gas. I drove it the half mile home and let the car sit until today. I went to where I normally fill up and topped off the tank with some 5% ethanol 89 octane, then I went for about a 50 mile loop and boy what a difference. about 90% of my problems have disappeared. the voltage still drops at a quick stop, but it doesn't get down below 12v on the dash. I'm gonna say that most of the problems I had were fuel related. the car was actually fun to drive tonight, sort of like how it should be.