Car stutter easily at low RPMs
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From: Fullerton
Car stutter easily at low RPMs
Not long ago I posted that the car stutters easily at low RPMs after the Vortech SC install. Well I believe I found the fix for it.
The idle fuel pressure was just a tad too high after using the Walbro 255lph fuel pump and the OEM Fuel Pressure Regulator. The stock OEM fuel pump and regulator idled at ~43psi. While the new pump drove the idle pressure up to ~51psi with the OEM FPR. To get the pressure back to stock, I just installed an AEM FPR 25-301 to adjust the idle fuel pressure back to 43psi.
Another way to compensate for the increased pressure, the installation manual recommended to drill a small bypass hole on the return line inside the OEM FPR to alleviate the extra pressure from the upgraded fuel pump. This is a jimmy rig fix and it should bring idle pressure back down a bit, but it can only be adjusted by the size of the hole you drilled. Once you drill the hole, you may not be able to reuse the OEM FPR if you take out the Vortech SC as the fuel pressure will be too low.
With the adjusted fuel pressure to 43psi, the power delivery feels smoother now. But it feels a bit less responsive when you gun it. Maybe its just the hotter weather this weekend. The VTEC engagement is less abrupt. I would like to dyno the car again to see if it improved torque delivery at certain RPMs. Oh, also with the lowered static pressure, it helps the RPMs go down faster when downshifting. Not quite the stock N/A setup, but close enough.
All along I thought that the mixture was too lean at low RPMs after the SC installation but it was actually richer which caused the sensitive drivability at low RPMs. I thought that the ECU will automatically adjust the fuel maps over time but it didn't adjust enough at closed loop learning.
One last thing, my fuel mileage before the installation for mixed highway and city was ~22-24MPG. After the SC install, it dropped to ~20-22MPG. Not bad for the additional power added. I bet my miles per gallon will improve with adjusted fuel pressure @43psi. I'll find out in a few fill ups. Hope this helps yall.
The idle fuel pressure was just a tad too high after using the Walbro 255lph fuel pump and the OEM Fuel Pressure Regulator. The stock OEM fuel pump and regulator idled at ~43psi. While the new pump drove the idle pressure up to ~51psi with the OEM FPR. To get the pressure back to stock, I just installed an AEM FPR 25-301 to adjust the idle fuel pressure back to 43psi.
Another way to compensate for the increased pressure, the installation manual recommended to drill a small bypass hole on the return line inside the OEM FPR to alleviate the extra pressure from the upgraded fuel pump. This is a jimmy rig fix and it should bring idle pressure back down a bit, but it can only be adjusted by the size of the hole you drilled. Once you drill the hole, you may not be able to reuse the OEM FPR if you take out the Vortech SC as the fuel pressure will be too low.
With the adjusted fuel pressure to 43psi, the power delivery feels smoother now. But it feels a bit less responsive when you gun it. Maybe its just the hotter weather this weekend. The VTEC engagement is less abrupt. I would like to dyno the car again to see if it improved torque delivery at certain RPMs. Oh, also with the lowered static pressure, it helps the RPMs go down faster when downshifting. Not quite the stock N/A setup, but close enough.
All along I thought that the mixture was too lean at low RPMs after the SC installation but it was actually richer which caused the sensitive drivability at low RPMs. I thought that the ECU will automatically adjust the fuel maps over time but it didn't adjust enough at closed loop learning.
One last thing, my fuel mileage before the installation for mixed highway and city was ~22-24MPG. After the SC install, it dropped to ~20-22MPG. Not bad for the additional power added. I bet my miles per gallon will improve with adjusted fuel pressure @43psi. I'll find out in a few fill ups. Hope this helps yall.
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