1984 with s5 13b N/A idle woes
 

okay so first off, i had my engine dyno tuned by a pretty reputable tuner. Before this tune my engine idled at 1500 cold and 1100-1200 hot. which was way to high, so i had the tuner set my idle down to 800-900. i noticed the next morning when i started the car and needed my headlights and wipers going that the car would stumble down to 600 rpm and it would quit the odd time. it should also be added that i have a rather customized ITB setup using tec3. when ever i first press the pedal theres a slight hesitation where my AFR gauge just blanks then the car will catch up. it drives perfectly until i slow down where the idle will once again drop down to 500-600 rpm. I put my laptop on the car and watched the fuel flow at idle. with no engine load ( no radio, fan motor, wipers or lights ) the car sits around 4.2-4.5 lpm ( pretty sure liters but i wasnt focused on the units of measure) then once i flick the lights on it goes to 3.9-4.2. i tried to set the idle higher in the program but the engine doesnt really respond. im thinking A, my alternator just doesnt provide enough juice at an idle speed to run my fuel pump properly, or B maybe my fuel pump isnt so great. its a walbro 255, but im tempted to think the alternator simply because the fuel pump wont stumble a bit all the way through my rev range. has anyone experienced this before? sorry if i am unclear.

welcome to the board. :)

firstly, which alternator are you running? secondly, i agree that that's where you need to focus since it seems to do it only under increased electrical load.

well as far as i know, its the stock alternator off of the 1991 motor. the motor was swapped when i bought the car, it seems stock and small. just curious if a bigger alternator would help or hurt the situation

well, you should probably start by having it checked for output. if it passes that, then your next step would be wiring.

have you double-checked your wiring? check out the schematics NZConvertible provided.

https://www.rx7club.com/2nd-generati...alt-s4-669675/

even though it's an S6 alternator, i included this one since it has some troubleshooting tips that might apply.

https://www.rx7club.com/2nd-generati...tartup-999751/

thanks diabolical, i will have to check into this more when i get the time.