running rich...new O2 sensor

[doug7x]

anyone have any ideas?...'91 Metro XFI...it's been sitting for 8 yrs, just got it running, runs pretty good, just a rough idle & black (carbon, not oil) plugs. Cap, rotor, wires, O2 sensor & plugs are all brand new, timing is @ 6 deg. BTDC. Air cleaner is not bad, cold air inlet is disconnected. (not plugged up) Exhaust seems OK, too.....Thanks

[doug2060]

Are you sure it's running rich? Is the check engine light on? There are still many things that will cause your bad idle. Have you put fresh gasoline in it? If it's been sitting that long and you're running on the old gas that could be a problem too. So many things... How's your EGR valve if equipped? Is the PCV clean? Old oil could have hardened in it. You will probably have to do some old fashioned trouble shooting here. If it's sat that long it could be anything.

[doug7x]

No to most...I read the plugs...it's rich. I've got it narrowed down to either a sticking injector, or for some reason, the ECM is telling it to run rich. (maybe the engine temp sensor?...I'm not sure how to test it) There are no trouble codes (OBD-I), so that's why I'm thinking bad info to the ECM. Any thoughts would be welcome...I've got plenty of time to wait, just no time to work on it...thanks

[Woodie83]

Could be sticky injector or bad fuel pressure regulator. Both are mounted on the top of the throttle body. If you look down the throttle body with a flashlight (some use a timing light) you should be able to see a nice cone shaped spray pattern coming from the injector. When you turn the engine off, it should stop cold, no drips. FPR can be tested by testing the fuel pressure on the return hose going back to the tank. Removal of either part can get tricky, the screws are Locktited. Warm it up with a hair dryer before approaching the screws, they're known to break off.

[Woodie83]

Also could be a temperature sensor, they can be tested too. You're going to need a Factory Shop Manual.

[BillCP]

I'm weeding though this myself on a 93 1.0L. From what I read, the TPS (throttle position sensor) sends info back to the computer. If the TPS is bad the computer can cause a rich burn...and other problems like not letting the auto tranny shift properly. I checked my tps and it's bad. Soon as its replaced I'll find out if the O2 code can be cleared and if the tranny shifts ok.

Bill

[kmguy13]

Does the cooling fan kick on? I have a 97 lsi 1.3l and it was running rich, and the cooling fan would not kick on. Turned out the temperature sensor was out of order and telling the computer it was -40F. As a result the excess raw fuel killed 2 os sensors until I figured it out. Runs much better now. Another symptom was difficult starts once it was warmed up.
Hope this helps