My check engine light was popping on and off while i would drive occasionally and i finally got around to pulling the code and ended up with a code 45, rich exhaust. At the time i brought it to my mechanic since i dont have a safe and reliable way to get under the car currently. He changed out the o2 sensor and checked all the grounds in my car and the other sensors and they seemed to be ok, but the light still is coming on when im driving then shutting off after a minute or two of being on. In fact it seems more frequent since he replaced the o2 sensor. Assuming the carb is tuned correctly and all of the above is accurate, what else could be causing the problem? Could it be a problem with the computer itself?

It may be a new or [different ] code ,check your stored codes ..

airpump not pumping nuff air into exhaust manifold/ catalytic converter?

I know we are all the time saying to check for vacuum leaks and to check and make sure the choke is pulling off all the way and there is a vacuum pot on the back of the carb(Pass. side) ,other than that your going to need someone to test the solenoids and the TPS in the carb to make sure they are working correctly if you have the computer controlled carb.To me thats where it sounds where the problem is.
This is the TPS throttle position sensor. http://www.oreillyauto.com/site/c/detail/BOR0/EC1014.oap?keyword=throttle+position+sensor&pt=02207&ppt=C0033
There is also a solenoid that controls the metering rods, the connector is on the top,front,pass. side of the carb and usually a blue color.Be sure to check the harness connector as they are known for getting brittle and loosing connection to the carb.

As sandblaster said check codes again could be a faulty tps happened to me

Here is the flow chart for code 45
Code 45 - Rich Exhaust Indicationhttp://www.alldatapro.com/alldata/PRO~V199824599~C4400~R0~OB0~P4R0H~N/0/41745988/42417544/42417552/42417554/34853741/34857029/34857030/34857663/122915129/145074190/145101864/42451607/41924738
Wiring Diagram for Code 45 - Rich Exhaust Indicationhttp://www.alldatapro.com/alldata/PRO~V199824599~C4400~R0~OB0~P4R0H~N/0/41745988/42417544/42417552/42417554/34853741/34857029/34857030/34857663/122915129/145074190/145101864/42451607/41924737

It's a Q-jet carb? The plastic float in those carbs sometimes becomes fuel-logged, and sink a bit, making the float level off, meaning a higher fuel level in the bowl, which makes for a richer mixture.

same thing happen to me , replaced thermostat and coolant temperature sensor, it fixed it. just a thought.

I was out of town over the weekend was too tired to deal with the car when i came home last night, thanks for the help so far.

It may be a new or [different ] code ,check your stored codes ..

I just finished checking, the only code that showed up was the rich exhaust code again.

I know we are all the time saying to check for vacuum leaks and to check and make sure the choke is pulling off all the way and there is a vacuum pot on the back of the carb(Pass. side) ,other than that your going to need someone to test the solenoids and the TPS in the carb to make sure they are working correctly if you have the computer controlled carb.To me thats where it sounds where the problem is.
This is the TPS throttle position sensor. http://www.oreillyauto.com/site/c/detail/BOR0/EC1014.oap?keyword=throttle+position+sensor&pt=02207&ppt=C0033
There is also a solenoid that controls the metering rods, the connector is on the top,front,pass. side of the carb and usually a blue color.Be sure to check the harness connector as they are known for getting brittle and loosing connection to the carb.

I do have the computer controlled E4ME q-jet, so i will try and look into this, how do you go about checking the solenoids and the choke coming off on time? I'm going to research it myself, but it never hurts too have more info on something. Also i am still not entirely sure how to go about checking for vacuum leaks, last time i hooked up my vacuum gage though, i was reading about 26 mmhg, which i know is on the high side, but i didnt have a T-connector so i just hooked it up to where the EGR valve connects to the carb.

Here is the flow chart for code 45
Code 45 - Rich Exhaust Indicationhttp://www.alldatapro.com/alldata/PRO~V199824599~C4400~R0~OB0~P4R0H~N/0/41745988/42417544/42417552/42417554/34853741/34857029/34857030/34857663/122915129/145074190/145101864/42451607/41924738
Wiring Diagram for Code 45 - Rich Exhaust Indicationhttp://www.alldatapro.com/alldata/PRO~V199824599~C4400~R0~OB0~P4R0H~N/0/41745988/42417544/42417552/42417554/34853741/34857029/34857030/34857663/122915129/145074190/145101864/42451607/41924737

Honestly i do not know what to do with the flow charts you posted. I'm still relatively new to working on cars.

It's a Q-jet carb? The plastic float in those carbs sometimes becomes fuel-logged, and sink a bit, making the float level off, meaning a higher fuel level in the bowl, which makes for a richer mixture.

The plastic float would be located in the float bowl right? If thats the case that's what i've thought it might be (but honestly i dont know enough about the car to know other causes) since my mechanic said the other sensors seemed to be working and he replaced the 02 sensor.


Edit: Not sure if its just me, but every time i refresh this page the images buzz posted change, is that supposed to be happening?

One thing to think about, is that if the coolant temp doesn't get up to like 195 degrees, the ECM will stay in open loop, operating like the engine is cold, and running rich. Maybe a new thermostat would help (?) A 192 or 195 is what's usually in there. Not sure what temp the ECM goes into closed loop, but it's up there near normal operating temp.
And like mentioned above, if the temp sensor isn't working right, and not giving the ECM the correct temp info, it may be the problem too.

One thing to think about, is that if the coolant temp doesn't get up to like 195 degrees, the ECM will stay in open loop, operating like the engine is cold, and running rich. Maybe a new thermostat would help (?) A 192 or 195 is what's usually in there. Not sure what temp the ECM goes into closed loop, but it's up there near normal operating temp.
And like mentioned above, if the temp sensor isn't working right, and not giving the ECM the correct temp info, it may be the problem too.

I'll keep that in mind, my temp sensor on the dash has always seemed to work, but it might be stopping short of the 192-195 mark.

One thing i noticed earlier today, not sure if its a new thing or not, is that when i hit the breaks to stop at a light my voltage meter drops from around the 13-15mark down to the 10-12 area, then goes back up when i start to accelerate. It got pretty cold today (its been hot the last few days and the fog rolled in this morning) if that has anything to do with it, and its been giving me more trouble on startups since the 02 meter was replaced, it stalled out a few times today. Could the alternator be going out and the poor voltage causing a rich mixture somehow, maybe not enough voltage flowing to the TPS or 02 sensor?

The simple answer is yes if the altenator is not producing enough for a certain amount of time and for OBD1 I don't remember the amount of time at this moment is,you can get computer codes or malfunctions.You could take it off and go to Kragens or Autozone and have it tested,they usually do it for free.
I was just reading the codes and it says it takes 5 minutes for this code to show ,so if it is the altenator testing it should show up real fast if the alt. is bad.Your problem could be the O2 sensor also.

I only want to comment about one part of the thread, The voltage drop at the gauge, I personally wouldnt consider that drop when stopping or braking considering the engine slows and the rear brake lites illuminate to be abnormal in itself.......:nothingtoadd:

looks like my car wasnt heating up past around 120* according to my mechanic, so i just took it home and picked up a new thermostat to install. Any tips for replacing the thermostat or is it really just as straight forward as the haynes manual makes it sound?

Thermostat replacement really is that easy. You got more antifreeze too, right? You're gonna spill some.

I dont have any on me, i can go pick some up in a friends car if too much spills out. Does a lot usually spill out?

replaced the thermostat yesterday after noon, the old one was an orangish color it was so grimy/old. The engine light hasnt come on while driving yet, so i'm hoping that fixed the problem. But, the temp gauge on the dash doesnt seem to be going any higher than it used to, is there any easy way to test if the temp sensor or gauge is malfunctioning or broken?

After replacing the thermostat the check engine light is still coming on intermittently while i'm driving. I'm kind of at a loss for what else good be wrong, the trusty haynes manual tells me to check/replace the charcoal canister, but i dont know how to really check that...or why exactly it would set off a rich exhaust code. I searched the forums for info on it, but the majority of threads about it are asking about how to remove it, not fix it.

Elkybrewer the charcoal canister is part of the vapor recovery system and if you posssibly over filled the gas tank in theory you could pull raw gas through the canister and ruined the activated charcoal and all the ones I've seen are a remove and replace on GEN5 .
My Chilton for DTC-45 says - Rich O2 sensor indication. The engine must run for at least 5min before this code will show and also says to check DTC-44 and it says the possible problem is a Faulty O2 sensor circuit.That being said it doesn't necessarily mean the O2 sensor is bad but changing it will eliminate it from the possible problem also check the wire going to it too make sure it's not damaged,mine got against the header and burned in two(previous owner).
Have you noticed a reduction in fuel mileage and what engine do you have?

did you disconnect the battery to clear the codes?

ive disconnected the battery to clear the codes several times and the code still appears. The car has gotten around the same mileage since ive owned it (about 6 months) when i first got it i was getting about 10mpg, and on my last tank i got about 11.5mpg. The o2 sensor was replaced by my mechanic around the time i started this thread. The engine is a 305, and is stock as far as i can tell.

I know that this is probably getting a little tedious but the O2 sensor was replaced before or after this problem came up?

after the problem came up, i had the o2 sensor replaced because i was getting a rich code, and the problem has persisted