Wild Fluctuations of AFR--Why? - The Saab Link Forums

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Performance Modifications for the NG900 / Old 9-3 This forum contains PERFORMANCE related Q&A's for the NG900 and 9-3. This may also include suspension.

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Old 04-07-2015, 08:31 PM   #1
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Wild Fluctuations of AFR--Why?

So, I'm running a wideband LC1 with the yellow wire to the signal wire from the OE narrowband. I'm also running dekka 630's and w/m.
I have noticed that logged afr's differ by about ~2 at either end of the map--high vacuum and boost. Cruising load AFR's remain unaffected as far as I can tell, but that may be from the masking effect closed-loop adaption has.
Boost afr's may vary from mid 10's to mid 12's. Seeing as how anything after ~8psi goes to open loop,I cannot see how the ecu would be making such drastic changes....is it the rift coefficient? The weird thing is, it will oscillate--seemingly every other run is rich as hell and then it leans out. Doesn't matter how I drive.

The strange thing is: I am running straight methanol, so no mixture changes possible.
Purge is disabled and the line is plugged.

fuel level is the same in the tank
Temperatures are roughly the same at each test run.

Any ideas? Is it hardware or is it electrical e.g ground issue?
I checked all the lugs and connections and they seem fine.
Thanks,
Cm
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T5 Suite Stg GpopT28, Deka 630's, Walbro 255LPH, 3 bar MAP @ 1.92Bar, W/M, Stg2 clutch, full suspension/bushes, 308mm brake upgrade, 3" turbo-back, big-azz FMIC &Oil-cooler, and fwdlol diapers.
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Old 04-09-2015, 10:41 AM   #2
Flirting With TSL Addiction
 
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Another theory I have is that since my DIC is weak, the fuel/air mix is not being combusted completely and thus leading to differing AFRs. Is this crack-pot or does it make sense?
-Cm
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T5 Suite Stg GpopT28, Deka 630's, Walbro 255LPH, 3 bar MAP @ 1.92Bar, W/M, Stg2 clutch, full suspension/bushes, 308mm brake upgrade, 3" turbo-back, big-azz FMIC &Oil-cooler, and fwdlol diapers.
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