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How to Guides / Troubleshooting / Re: Diagnosing Vacuum Leak Locations - Not PCV/Rear Breather
« Last post by dadawg22 on February 05, 2026, 11:02:45 am »Found the source(s) of my issues. There was a split in the brake booster hose assembly 1K0612041GM underneath one of the hose clamps which was not visible until disassembly, as well as cracks on the lower tube that runs below the HPFP (also not visible until I pulled the assembly out).
Replaced this part and started the car, which caused all the cylinders to misfire. However that was likely due to the ECU using the fuel trims compensating for the vacuum leak as after wiping the codes and driving the car hard I'm happy to report no more CEL.
Unfortunately I can still smell fuel in the cabin when the HVAC system is running, but I noticed that the hose for the low pressure path coming out of the bottom of the HPFP has surface cracks. Will replace that part asap and hopefully all will be right again with this car, at least until the DV goes.
Speaking of the DV, the car makes a somewhat concerning rattling/almost wheezing noise when the RPM's drop, usually after lifting off the gas. I'm guessing DV but if anyone has had similar issues I'd love some input.
Replaced this part and started the car, which caused all the cylinders to misfire. However that was likely due to the ECU using the fuel trims compensating for the vacuum leak as after wiping the codes and driving the car hard I'm happy to report no more CEL.
Unfortunately I can still smell fuel in the cabin when the HVAC system is running, but I noticed that the hose for the low pressure path coming out of the bottom of the HPFP has surface cracks. Will replace that part asap and hopefully all will be right again with this car, at least until the DV goes.
Speaking of the DV, the car makes a somewhat concerning rattling/almost wheezing noise when the RPM's drop, usually after lifting off the gas. I'm guessing DV but if anyone has had similar issues I'd love some input.

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