My car is a 1989 305 TPI and over the past few months I have noticed an abnormal amount of black soot on the rear bumper directly above the tailpipe. Obviously the car is running rich. However, my car constantly throws an "oxygen sensor LEAN" code.
The engine sometimes hits an RPM wall and will not rev. This is a lean condition.

Can anyone explain this? Is my o2 sensor measuring lean, and then the computer tries to compensate, adding too much fuel, causing my rich condition?

Please help!

 

Have you changed your O2 sensor? It could be giving false lean readings causing a rich condition. Also, an exhaust leak before the O2 sensor could do the same. The "RPM wall" could be the converter plugging up from running rich.

Just some thoughts!

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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!

 

O2 sensor is original and has 93k on it.



[This message has been edited by JeffP (edited November 12, 2000).]

 

It would probably be a good idea to replace the O2 sensor. You should also check your fuel pressure regulator since they can go bad and make it seem like your 02 sensor is at fault.

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92 Camaro RS LO3, 5-spd, T-tops
Mechanics:
Open Air Element w/K&N Filter, Flowmaster 3" Cat-back Exhaust, Z28 Grille w/aftmkt fog lamps
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-90 Amps powering 2 12" Pro Red subs and 4 Infiniti speakers.
NEXT UP: SLP 1 3/4" Headers/Y-pipe, Centerforce Dual Friction Clutch kit