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Discussion Starter #1
I am getting codes 33:insuffiecient EGR flow as well as codes 41 and 91 which translate to the same thing for each bank (left and right): EGO/HO2S oxygen sensor voltage lean and NO EGO sensor rich/detected. The car has a 351 with cam, long tubes, no smog pump and the heads have no air holes. My question is: are these codes normal given the car described or should I check further? Thanks in advance.
 

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Replace the o2 sensors and check the EGR valve. If your running no emmisions equipment then you will have to have a chip or tuner to turn the EGR off or it will keep posting the DTC.
 

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One GTOneLX said:
I am getting codes 33:insuffiecient EGR flow as well as codes 41 and 91 which translate to the same thing for each bank (left and right): EGO/HO2S oxygen sensor voltage lean and NO EGO sensor rich/detected. The car has a 351 with cam, long tubes, no smog pump and the heads have no air holes. My question is: are these codes normal given the car described or should I check further? Thanks in advance.
Well before you go off and buy some O2 sensors......check to see if the HEGO ground is hooked up. It is the orange wire that comes off the injector wiring harness and hooks to either the rear of a head or an intake bolt.
Make sure that ground is in good shape 1st.

Casey
 

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Discussion Starter #4
I will check the ground. Will the O2 sensors from my speed density '87 work on my '89? That might tell me if the 89's sensors are the issue since the '87 has very low miles. Thanks for the replies.
 

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Sounds like a bad EPT sensor (the little thing on top of the egr valve). Change it and run some seafoam thru it, should be okay after that.
 

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Discussion Starter #6
Re: Re: EEC IV experts, please analyse codes

C. Johnson said:
Well before you go off and buy some O2 sensors......check to see if the HEGO ground is hooked up. It is the orange wire that comes off the injector wiring harness and hooks to either the rear of a head or an intake bolt.
Make sure that ground is in good shape 1st.

Casey
The ground was bolted to the EGR bolt. I moved it to the back of the head where it would be stock.
 
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