So I have been trying to diagnose this problem for months now without any luck, so I figured I'd come on here and try to get some ideas. Symptoms: 1 Car runs extremely rich 2 When cruising and going to WOT rather than passing gear kicking in it acts like it's going to cut off and gets sluggish. 3 I can hear a slight whistle if I hold the gas at 800-1000RPM in park but anything further and it goes away (even just 2-3RPM different over 1k) Things I've tried to remedy the problem: Swapped out the entire computer from my wrecked 89 Formula and bought new O2 Sensor. I've also checked all connection and made sure there were no obvious leaks, but with that whistling noise I must have a air leak somewhere (could this cause my issues with passing gear?) Also when I do the paper clip trick to get the computer to run a simple diagnostic it comes back with normal... In park the card seems to act fine to WOT, but in gear WOT makes it almost die. I have a spare 305 TBI + 700R4 transmission, but I'm not trying to into that if this is just a simple fix. Does anyone have any idea of a way to diagnose the problem or any idea to what the problem may be? I'm thinking of making one of those harnesses that plug into the Car computer then into my Laptop and diagnose it that way if I can't get any other ideas. Thanks for any help, Led

May seem stupid but i had several cars come in like that with plugged cats. May be to much pressure under load. Just a thought

Well that my be possible but wouldn't it be less likely with a low flow cat like mine:



Tearing my exhaust apart could be an option, but why would this symptom only be present at rolling WOT and not during park WOT.

Yes, Its still possible.. Its more likely to do it while under acceleration due to the load being put on. Its like a faulty fuel pump/filter. You notice more when your driving than in park. Not trying to contradict your thoughts but its worth a shot to unbolt the flang's and take it for a spin. Your not out anything other than a hour of labor. That would also explain the whistle with all that back pressure. Or you could simply put your hand over the tail pipe and see if it feels abnormal. Does it smoke? Does it smell unusual? Is it Only while warmed up or even when your vehicle is cool? Just a refresher and im sure you know this...The car when cold is in open loop. After the car warms up it goes into closed loop (i.e. O2 feedback) Once a certain load/throttle position is achieved they will switch back to open loop. (reading from fuel map and not O2 sensor. Hope you understood all my blabber

Yes, Its still possible.. Its more likely to do it while under acceleration due to the load being put on. Its like a faulty fuel pump/filter. You notice more when your driving than in park. Not trying to contradict your thoughts but its worth a shot to unbolt the flang's and take it for a spin. Your not out anything other than a hour of labor. That would also explain the whistle with all that back pressure. Or you could simply put your hand over the tail pipe and see if it feels abnormal. Does it smoke? Does it smell unusual? Is it Only while warmed up or even when your vehicle is cool? Just a refresher and im sure you know this...The car when cold is in open loop. After the car warms up it goes into closed loop (i.e. O2 feedback) Once a certain load/throttle position is achieved they will switch back to open loop. (reading from fuel map and not O2 sensor. Hope you understood all my blabber

sorry for the double post...OOPS

Well I checked the exhaust flow and everything felt/smelled normal for 305 TBI. Does anyone else have any ideas?

The ECM wont go into closed loop unless certain conditions are met. Check your coolant and intake air temp sensors to make sure they have resistances that make sense (you can find a chart showing temp vs. resistance). If they are at the extremes, then the ECM usually catches that and sets a code. If they are just reading wrong, then the ECM might think the engine isn't warm yet and prevent closed loop operation. If they are reading low, then the engine will run rich because the ECM is feeding it extra fuel. Just tossing that out there.

I agree with afremont...that was gonna be my next suggestion.Could be somthing as simple as a thermostat

you should consider the oxygen sensor too... mine wouldnt go into closed loop because my oxygen sensor was bad.... no check engine light came on either.... after i replaced that car went into closed loop...