NoKz
Speed Limit Tester
- Joined
- Jul 23, 2018
- Threads
- 28
- Messages
- 842
- Reaction score
- 1,110
- Location
- SoCal
- Vehicle(s)
- '18 Si Coupe (Sold 12/2021)
- Vehicle Showcase
- 3
- Thread starter
- #1
Hey guys, I'm curious to see if anyone can lead me in right direction to continue diagnosing the issue with my 2018 Civic Si Coupe.
The specs are as follows:
Symptom(s): Car breaks up in gears 3-6 when over 3200 RPM and/or 30% throttle. After 20 or so minutes of highway driving, the issue appears to dissipate.
Description: When I start my car to drive it, I usually let the ECT warm up until about 170'ish degrees before driving off. I monitor this using TunerView on my head-unit. Once the vehicle is warmed up, I go about my drive. Primarily, the vehicle is used to get to work and back, which is roughly 62 miles round-trip.
When starting my commute, if I take 3rd gear over 3000-3400 RPMs it will break up like the vehicle is cutting ignition timing. If I push through it, the vehicle will go into limp mode and I have to restart it. If I let off, I can continue driving without issue. When going into limp mode, I get no check engine lights, no error codes, nothing.
After about 20 minutes of steady driving on the highway, the issue appears to go away. I can drop down to 3rd gear and rip on the car, but it will break up around 5K instead of 3K. Normal street driving is fine and I can rev beyond 3K without issues. But if I shut the car off and restart it, the issue comes back.
I actively monitor my Knock Control, Fuel Pressure Target, Fuel Pressure and AFR. My Knock Control is consistently at 0.49 on E40 and can go up to 0.54 when on 91 octane only. Previously, with different spark plugs, it would be all over the place. I replaced them with OEM spark plugs and it has been much more consistent.
I have been trying to diagnose this issue for a while, but have been unable to narrow down the root cause. I have done the following in attempt to try and diagnose/fix the issue.
The specs are as follows:
- PRL Cobra CAI w/Race MAF
- PRL Catless Downpipe
- PRL Frontpipe
- KTuner Flex-Fuel Kit
- E40 Fuel Blend (91 Oct & E85)
- KTuner v1.2
- TSP Stage 2 Tune
- Google Sheets Document (Spreadsheet Line #3710 For An Example)
- Google Drive Download (KDLG File)
Symptom(s): Car breaks up in gears 3-6 when over 3200 RPM and/or 30% throttle. After 20 or so minutes of highway driving, the issue appears to dissipate.
Description: When I start my car to drive it, I usually let the ECT warm up until about 170'ish degrees before driving off. I monitor this using TunerView on my head-unit. Once the vehicle is warmed up, I go about my drive. Primarily, the vehicle is used to get to work and back, which is roughly 62 miles round-trip.
When starting my commute, if I take 3rd gear over 3000-3400 RPMs it will break up like the vehicle is cutting ignition timing. If I push through it, the vehicle will go into limp mode and I have to restart it. If I let off, I can continue driving without issue. When going into limp mode, I get no check engine lights, no error codes, nothing.
After about 20 minutes of steady driving on the highway, the issue appears to go away. I can drop down to 3rd gear and rip on the car, but it will break up around 5K instead of 3K. Normal street driving is fine and I can rev beyond 3K without issues. But if I shut the car off and restart it, the issue comes back.
I actively monitor my Knock Control, Fuel Pressure Target, Fuel Pressure and AFR. My Knock Control is consistently at 0.49 on E40 and can go up to 0.54 when on 91 octane only. Previously, with different spark plugs, it would be all over the place. I replaced them with OEM spark plugs and it has been much more consistent.
I have been trying to diagnose this issue for a while, but have been unable to narrow down the root cause. I have done the following in attempt to try and diagnose/fix the issue.
- New OEM Spark Plugs
- Swapped Coil Packs w/Wife's Si (No Change)
- Flashed to TSP Stage 1 Tune with 91 Octane
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