05-04-2021, 08:03 AM | #1 |
Drives: 2017 Camaro SS Join Date: Aug 2020
Location: SC
Posts: 9
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High LTFT and Misfire
My car has a problem with misfiring when it starts cold, always cylinder 4. HPtuners shows it misfires around 80 times, and then once the idle dies down it mostly stops. However, anytime I let off the gas from light acceleration, cylinder 4 misfires twice. I have a few other cylinders that misfire a few times but I understand that is mostly normal.
I also noticed that my LTFT reads pretty high, anywhere between 15-25%. I got P0171 and P0174 codes while driving the other day, about 20 miles after I used the CRC intake cleaner. I have a log from a few months ago where it showed my LTFT being between 0-5%. I have tried the following to fix it: Cleaning the intake with CRC intake cleaner Swapping the coil packs and wires between cylinder 2 and 4 Bottle of techron fuel cleaner in the tank. Spraying small amounts of ether around every vacuum line I can find, but no surges or changes on idle when I do it Cleaning the MAF sensor with CRC MAF cleaner At this point I'm not sure what the problem is. Someone said it could be an 02 sensor that got dirty after using the CRC/techron, but the o2 sensors still read as normal when I compare recent logs to past logs. Could it be a bad injector? Mods: E85, GM CAI, Borla Axleback Last edited by StopShoe; 05-04-2021 at 08:37 AM. Reason: Forgot to list mods |
05-04-2021, 08:27 AM | #2 |
Drives: 2018 Chevrolet Camaro 2SS 1LE 6M Join Date: Jul 2019
Location: California
Posts: 283
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List your mods-it may help to troubleshoot.
Try a fresh set of plugs. It could be an injector-if you don't have any vacuum leaks, that could be the cause of your misfire and your high fuel trims.
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Bolt-ons.
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05-04-2021, 08:39 AM | #3 | |
Drives: 2017 Camaro SS Join Date: Aug 2020
Location: SC
Posts: 9
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Quote:
So even if I have 1 injector that is bad/failing, it would cause high fuel trims on the other bank? Also, when looking at the car from the front (cooling reservoir on the left), it goes 2, 4, 6, 8 with 2 being the closest to me, right? |
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05-04-2021, 09:37 AM | #4 |
Drives: 2018 Chevrolet Camaro 2SS 1LE 6M Join Date: Jul 2019
Location: California
Posts: 283
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Firing order/cylinder layout. Except that the firing order is : 1 – 8 – 7 – 2 – 6 – 5 – 4 – 3
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Bolt-ons.
Last edited by NA18CamaroSS; 05-04-2021 at 09:46 AM. Reason: text |
05-04-2021, 10:45 AM | #5 |
Drives: 2017 Camaro SS Join Date: Aug 2020
Location: SC
Posts: 9
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05-06-2021, 07:19 AM | #6 |
Drives: 2016 1SS NFG A8 Join Date: Aug 2017
Location: 46804
Posts: 6,810
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Unmetered air entering the system can cause false positive fuel trims. Check all your connections between TB and Maf.
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2016 NFG 1SS A8
Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA |
05-13-2021, 08:23 AM | #7 |
Drives: 2007.5 Duramax Join Date: Nov 2016
Location: Houston
Posts: 101
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What’s your alcohol content reading currently? If your flex sensor is not working correctly it would dump around that much fuel.
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05-19-2021, 04:28 PM | #8 |
Drives: 2018 Camaro 1SS Join Date: Apr 2018
Location: Gilbert, AZ
Posts: 47
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My fuel trims were about 17% high when I took my car to the dyno. I thought that maybe my wideband or O2 sensor was bad. After talking to my tuner and sending him my dyno logs he informed me that I needed to go to a 95mm TB as my current TB (Solar 87/91 ported) was causing it to pull vacuum and running rich. I have currently swapped out the TB for the 95mm and working on the new tune. Hopefully that takes care of my rich condition at WOT.
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Camaro 1SS M6 - LT2 IM, 1-7/8" Speed Engineering Headers & catless 3" x-pipe to Borla ATAK NPP axle back, Mishimoto Catch Can, BTR Rocker Arm Trunnion kit, E85, 95MM TB, JLT CAI, 180* T-Stat, & SJM line lock - Tuned by Ted Jannetty
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03-13-2024, 04:37 PM | #9 |
Did you ever figure out the issue? My car is also misfiring on cylinder 2 only when I’m on E85. Have headers, manifold, X pipe, intake, tune. Just ordered a 95mm TB. During logs, my TB only opens to around 56% during WOT.
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03-17-2024, 08:22 AM | #10 |
Drives: BLUE CAMARO ZL1 1LE M6 Join Date: Jun 2009
Location: ON THE DYNO WATERBURY CT.
Posts: 15,225
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I retuned it and all is well.
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Celebrating 37 years Performance parts, Installation, Fabrication, Dyno tuning, Remote custom tuning, and alignments. 203-753-7223 Waterbury CT. 06705 email tedj@jannettyracing.com |
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