Help!!!! I've tried just about everything.new o2 sensor, new ecm I burn proms and have changed settings to make o2s enable sooner but made no difference.The scanner reads that it is crossing over but o2 voltage stays between 458 and 453 only affected when rpm change. And to add to this tps reading is'nt constant. I've lowered the threshold for maf error to 30 thinking it might be it but still no code but ran better and idled higher. any ideas????
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It sounds like the ECM may be going out. With the O2 staying between 458 and 453 that isn't enough swing for the ECM to go closed loop. But with the TPS reading also being off, it points to the ECM.

With the engine running tap on the ECM. If the engine changes or stumbles it points to an ECM.

On the other hand, check the battery cables for good clean tight connections. Then the grounds on the back of the heads. the ECM needs to have decent power and good grounds to the engine to operate properly.

RBob.

 

thanks rbob I'll give it a try.