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Afr At Idle

mynameisdaniel

By mynameisdaniel,
in Engines & Forced Induction

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mynameisdaniel Contributor

mynameisdaniel

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In the process of getting my car running 100% before starting to tune/track it. The head gasket has just been replaced with everything cleaned out very well.

Car is an R33 GTS-T Series 2 manual with the standard ECU plugged back in (also have Z32 and RB20 Nistuned ECUs for it). Has full 3/3.5" exhaust, FMIC, fuel pump with everything else standard (including fuel rail, injectors and FPR).

Base timing set to 15 degrees correctly and I have it idling at 800rpm in base timing mode (ConZult). I've installed a wideband (LC-2) and have been monitoring AFRs and have found after startup while warming it has an AFR of about 5. When the car is well and truly up to temp the AFR sits on about 7 varying slightly but no higher than 8.0. When I hit the throttle revving to 2.5/3k it approaches closer to 14.7.

I assume the car shouldn't be idling this rich? But I'm not sure what is causing it - the standard O2 sensor could be dead but would the ECU have enough correction to run it this rich based on O2 feedback?

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mynameisdaniel Contributor

mynameisdaniel

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The LC-2 doesn't have any air calibration like the LC-1 did. It supposedly does it itself when you first power it. I thought it was the problem initially myself but the fact it reads 14.7 with higher revs and then maxes out on deceleration (no fuel) have me thinking it isn't. Plus the car is definitely running rich based on exhaust smell/residue on bar (car has a cat still). The sensor is brand new, 30 minutes of use and correctly positioned.

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mynameisdaniel Contributor

mynameisdaniel

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Just looked into the calibration some more and it can be redone so I'll give that a shot and see how it goes. Failing that, is there some way of knowing for sure when the car is in closed loop or not?

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