Having one issue after another after the head swap. the engine is a 370, 236/242 cam, bolt ons.ect.. After the head swap the a/f was dialed in and about 500 miles where put on. Out of nowhere the truck starts surging from 900 to 1200 at idle. then started throwing maf code and high idle code.. Swapped mafs and nothing changes, swapped map and it seemed to clear it up. Now the a/f has gone down into the deep 10s and has a slight miss at light throttle. Swapped plugs, and wires and literally went and made more wot passes 30 min later and the a/f was in the low 11s and still has a slight miss at light throttle.. This is all on the same tune that was in the high 12s. any ideas on what might have changed? any ideas please
thanks

 

intake gaskets?

 

swapped, brand new... but that would make it run lean id think. not get richer?

 

you would think, but the O2's will read the extra air (unmonitored coming in the intake side) and richen up the mixture to compensate.

someone correct me if im wrong.

 

That makes since but wouldn't my wideband be picking up the same lean condition as the o2s are seeing

 

have you modifyied the VE table to accomidate for the 'different' airflow of the new heads?

You could also have an air leak somewhere, maybe the oppsite bank as the wideband is in since that reads good.

 

Yes. Got the tune lined out on the dyne and then fine tuned on the street. All that was done about 500 miles before it started acting up. Any ideas on looking for the leak? I don't have evap at all so I don't think a smoke test can be done. And iv sprayed all over with starter fluid with no results

 

Have you reset your LFTs since swapping the sensor? Did you install the same PN sensor?

 

Yes same part number. How do I reset the LFTs?

 

its in the scanner.