having a continued prob w/ my 86S hoping to get guidance.
car began throwing TPS code earlier in year. replaced the TPS. yet i still throw the code each time the car is cold started. once the car warms up, it doesnt throw the code until the next cold start.
it wont hold a stable idle speed even after full hot. idle jumps from 800-1,500 rpm. very erratic idling, never did this before, and the a/f ratios jump as the idle moves.
at steady state cruise, w/o moving the throttle, a/f ratios will look fine bouncing 14.5-15.0, but even though the throttle is not being moved suddenly go full lean (off the scale), then an instant later, go to 13.0 or richer, then an instant later return to normal. this cylce of normal to full lean to way rich and back to normal will repeat at steady cruise 55 mph driving. this a/f ratio jumping is exactly what is does during the erratic idle, leading me to believe this is an electrical problem.
checked ground wires: i have zero ohms from fuel rail to neg batt post, zero ohms from fuel rail to firewall, zero ohms neg batt post to engine block.
voltage checks w/ key on:
3.5 volts going into the TPS at the 6-way connector
.9 volts coming out of the TPS at the 6-way connector
as i rotate the throttle, TPS voltage rises to 3.5
is the 3.5 volts into the TPS too low? my manual says 5 volts goes to the TPS, could that be the problem? battery voltage is 13+.
any other advise as to why i am throwing TPS code when cold, getting erratic idle, and getting erratic a/f ratios at steady state cruise?
thanks.