ctgreddy

about 3 weeks ago i posted about my car hunting for an idle. no codes present, had one for a water temp sensor and replaced it. it was an intermittent problem for a while, every now and then at a stop light it would just decide to not want to idle, but now it does it every time it's at idle, it fluxuates between 500-1500 rpm. it's running rich at idle which i'm thinking might be why it's so rough? when it used to actually idle ok the afr would be at around 14.0:1 so a little rich, and when it's bad it fluxuates between 11 and 14:1. timing is set at 10*, tps volts with koeo is .98. when i did a base idle reset i unplugged the iac and nothing changed, isn't the idle saposed to change? as of now i'm thinking either the iac is bad or the o2's possibly since i used leaded 110 the day the problem started.

while driving and wot afr's are perfect and it drives just fine. only issue is at idle. so what does everyone think?

ctgreddy

bought a new iac and same thing. cleaned the maf and no change. i hooked my dmm up to the o2 sensor and in closed loop and the engine at 2k, the reading was flucuating rapidly between .4 and 1 volt, but my wideband read between 14-15.0:1 the whole time. is this normal or no?

AdderMk2

It's too bad you didnt get a quarterhorse, because I'd love to see the tune thats in your car.

mattdel

first problem would be the leaded gas. no good for o2's. you might have gotten lucky and not fouled them up too bad, though.

secondly i'd look into the IAC.

67mustang302

What about plugs/wires?

ctgreddy

wires are new frpp's. plugs are new (about 1k miles) autolite 3923's. when i put the colder plugs in was also when i installed my nitrous, so would having too cold of plugs for the motor when it's not spraying cause this at all? i'm guessing no but who knows.

67mustang302

It shouldn't. A colder plug would just get deposits on it. Unless your plugs somehow fouled out(unlikely) then the heat range won't matter.