Code meaning

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mclark

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Can anyone tell me where to start in trying to fix the listed codes:KOER codes 327,536,551/ KOEO codes 175,176,177,189. The 94 Sho auto feels like it starves of power around 80 mph, I can slowly apply throttle around that speed and barley accelerate, any ideas where to start to fix the problem. Thanks
 

SHOdded

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175 (M) Oxygen sensor not switching- system was at adaptive limits - Left orr Front HO2S - Fuel control
176 (M) Oxygen sensor not switching- system is or was lean Left or Front HO22SSS - Fuel control
177 (M) Oxygen sensor not switching- system was rich Left or Front HO2S - Fuelcontrol
189 (M) Fuel system was lean at partthrottle - Left or Front HO2S - Fuel control
327 (O,R,M) EGR feedback signal is/waslow - EVR or PFE
536 (O,R,M) Brake On Off open or shortedto ground - BOO
551 Problem in Intake Manifold RunnerControl (IMRC) solenoid/circuit - Solenoids

looks like a good intake cleaning + new o2 sensors are due ... i think the cats are ok but doesn't hurt to check them.
 

Greg Corcoran

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I guess next step is to clear the codes and see what comes back.
It seems if they all come back that the left O2 sensor is defective, the connector is not fully seated to the sensor, or there is a problem with the wiring. Likewise for the intake runner solenoid. Maybe go over the wiring/connectors with a fine tooth comb looking for loose or broken wires on those 2 circuits.
 

BaySHO Performance

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The 551 is the prime suspect. Could be that the butterfly valves aren't opening at 4K RPM. If you look at the rear butterfly valve, you will notice a small tab on it that is in the down position. You will be able to lift it up by hand. That valve is open engine off, allowing air through the short runners. Start the engine and see if the tab goes up, closing the valves. If not, it could indicate a vacuum leak somewhere. Now rev the engine above 4K to see if the tab goes down again to open the shorties. If not, there could be a problem with the IMRC bolted to the back of the intake or the wiring.
 
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