I don't have an A/F meter so no way to verify, but I swear my car runs pig rich. The smell out of the exhaust is horrible and the motor is only about 20,000 miles old. If you stand by the car while it's running or drive with the windows down, your eyes start to water and burn. So what are some things I could look at that may be contributing to a rich condition?

 

This a new motor or a stock 350 TPI?

If your motor is stuck in open loop it might run really rich. Not exactly sure. 90 is SD right? Bad O2 sensor? Bad catalytic converter?

 

Remanufatured long block put in about 20,000 miles ago, retained original TPI stuff. Nothing changed there, except for new distributor, plugs, wires, ignition coil, ignition module, fuel pump and fuel pressure regulator.

It just rans really crappy. Never really dies once it's running, but the idle is by no means smooth and again, stinks like crap. The catalytic converter was replaced with an aftermarket one only about 50,000 ago. Also, when I say it stinks, I don't mean like rottin eggs, but smells like too much gas in there.

How can I tell if it's in open loop? I wonder if that's my problem? Just to let you know, when I first start it up, it will idle pretty high, then slowly work it's way down and at some point, you can hear something different about the engine, like it all of a sudden drops idle. Wouldn't that indicate it's just went to closed loop??

 

scan your codes check your o2 sensor check your timing make sure its not off
dont drive it rich like that or it will warp your headers and turne them blue making exhaust leaks bad bad

 

Run it for a bit and when it gets to operating temp, get the voltage reading off the O2 sensor.

 

How would I get the voltage reading off the O2? I think there is only a single wire coming off of it, right?

 

backprobe the single wire and ground the other terminal of the meter thats how the sensor works, one wire is power and the sensor grounds itself

 

O2 sensor voltage at operating temp is .395 volts.

So is that good or bad?

BTW, it does seem as though I have an exhaust leak on the passenger side and seems to be coming from the header as you suggest. So that does tell me I'm running rich, but I just can't figure out why? Could it be that my computer is shot? But being software programmer, I know that code doesn't just change on it's own so I have hard time believing anything is wrong with the computer.

Also, I unplugged the MAF sensor while it was running and initially the car dropped down in idle then it picked back up and didn't seem to run all that much differen with the MAF unplugged, but it wasn't as responsive to throttle input. What does this tell me??

 

0.395 is lean and therefore the ECM will try richen it. Soooo, that leaves us the question of whether the thing is actually lean (look at plugs) or whether there is air entering the system on the driver side .

 

if you car is running normally(on all 8 cylinders) and you have no codes...
your O2 sensor is working? run the engine at 2,000 RPM let it warm up. Watch the voltage it should start varying between .150mv and .850mv. If it is cycling then let it idle. It should cycle the same. You're O2 is working but could be lazy or by now fuel fouled. You can check your O2 sensor respose time and your MAF frequency with a Snap On vantage multimeter. You're sensors could be reporting bad info and not set a code. Also you ECT or coolant temp sensor could also give false info if its reading too hot the ECM leans out the A/F mixture. An exhaust leak before the O2 sensor will give false info to the sensor, it sees all that air and reports to the computer that the system is lean, therefore the ECM will increase pulse width of the injectors. Thus a rich condition. Do you have any vacuum leaks? same thing will happen, A/F is lean so ECM will richen up. Also if you have access to a scanner look at your baro reading with key on eng off. Make sure its reading in the correct range. Then with engine warmed up look at your MAF voltage and your MAF gm/sec or frequency. Also with this going on your Intergrater/Blocklearn should have been driven up to richen the A/F mixture and if it can't it will top out and return to 128. With the scanner you can also see if the car is in closed or open loop. Check to see if the timing connector hasn't been unplugged, and be sure when you check th base timing you indeed unplug the timing connector. If timing is off this will affect the performance. Hope this helps...

 

Sorry guys, I think it was a false reading because I had the car off. I didn't realize I was supposed to leave it running while testing, I just left the ignition on. I did let it get to operating temp though before testing. But now reading your posts, I guess I screwed up! I'll try it again tonight with the car running and see what happens.

Oh and it is a new O2 sensor put in only about 500 miles ago if that...

 

BTW, I think I really got to get a laptop so I can hook up the WinALDL software to see what's going on in my computer's brain. May give me some insight to my problem.

 

Okay, voltage reading on O2 at idle with the car at operating temp was about .625 volts. It did flucate a bit, but the average was right about .625. What does this tell us? I didn't do it at 2,000 rpm yet cause it was getting late and I don't want to bother my neighbors any more. If I need to take a reading at 2,000 rpm for you to determine anything, I'll do it early tomorrow and let you know. But in the mean time, does the .625 tell you anything?

 

Idle with 0.625V is not that bad. It should bounce up and down because it is going from rich to lean and back to rich and so on. Find us the voltage when it is running "pig rich". Unfortunately this reading only gives us what the left bank is doing so the way to extrapolate what the right side is doing is to check and compare the plugs.

 

The thing is that it always runs pig rich. Well, let me just say that that is my assumption because I do not have an A/F meter to prove it. What I mean by pig rich is that the car smells horrible. It really makes you want to cough and your eye start to burn if you stand to close to the car, anywhere around the car, but obviously more as you stand near the rear. Something is just not right. The cat was replaced about 50,000 ago with a high flow after market. Could that cat not be doing it's just and that's why it smells like this? I did pass smog not too long ago, but they do seem pretty leaneant on the parameters, so that's not to say that my car was running perfect by any means.

I checked my plugs earlier and they did seem to be pretty consistent from side to side. Is it possible that my fuel injectors are old and therefore putting out more gas they they should be?