4th gen owners...what are your AFRs?

My 4th gen swap is running the factory ECU. I have a 3 inch turbo back exhaust, larger water intercooler, and manual boost controller. I hooked up a nice AEM wideband to moniter AFRs. Under idle and lower load driving, its a nice 14.5---15.2. But under full load, its indicating low 10 to 1 AFRs sometimes. Is this normal to run this rich? The car drives like a bat out of hell, so I dont think its really hurting performance.
 

dbucks2k

Member
If you have an ecu for an automatic there's been debate that they run rich. I haven't got an afr gauge on mine yet so idk.
 
Anyone else with a 4th gen swap and a wideband? What are your typical numbers? Is it normal to see the AFRs dip into the low 10 to 1 AFR? Its only happening under full load. The car seems to be OK for fuel consumption. About 17mpg city and around 22-23 on the last highway roadtrip @70mph.
 

CMS-GT4

Active member
My 205 engine was also pretty rich. If there are any faults, it gets considerably richer. Even without faults, I found that the quality of the o2 sensor contributed to extremely rich conditions.
 
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