F/IC 8 Frequency in/out dropping | AEM
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kpforce1
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F/IC 8 Frequency in/out dropping

I have a 470hp DOHC supercharged v8 from an 08 cadillac STS-V in my AWD 05 Cadillac SRX. The FIC has worked wonderfully until the engine gets half way warmed up. The problem is with my MAF frequency input/output. The hotter things get the more the input frequency drops out until it basically stops completely with a random input here and there so I get codes about MAF frequency low input , throttle body performance and air intake system performance etc. The ECM puts the injectors in a "default" map due to the codes so I cant tune.

I have checked the wiring continuity and power/low ref. to and from the MAF. O even ran a new signal wire directly from the MAF to the FIC. Is there something I am missing? I need to get this squared away so I can start tuning.

kpforce1
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Last seen: 4 months 2 weeks ago
Joined: 01/16/2019 - 18:46
I forgot to mention if I run

I forgot to mention if I run the maf directly to the ECM I do not get codes other than a MAP correlation due to more air.

kpforce1
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Last seen: 4 months 2 weeks ago
Joined: 01/16/2019 - 18:46
I rewired the MAF signal wire

I rewired the MAF signal wire and low reference directly from the ECM to the MAF, the F/IC signal ground was tied into the low reference for the MAF circuit as well and I thought it was fixed until everything was up to operating temp. It started dropping the signal again. Anyone have an idea of what I need to do here?

kpforce1
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Last seen: 4 months 2 weeks ago
Joined: 01/16/2019 - 18:46
I discovered another

I discovered another potential cause. When the dropping of signal occurs, I can turn the 12v ign power off and it reappears instantly. Turn it back on and it drops instantly. What is going on? I have sourced power from different sources (ECM, fused circuit, and the battery directly) and it doesn't seem to matter. I have done the same with grounding.

When I scoped both the input and output from the FIC, the input was never an issue, only the output is a problem. The square wave starts intermittently dropping out but the input is unchanged. Why then would the fic indicate the input is dropping when it is not?