Random misfire
Thread Starter
Staging Lane
Joined: Apr 2018
Posts: 91
Likes: 14
Random misfire 08 Super 5.3L. Replaced spark plugs, no change.
Most obvious during light throttle and torque converter locked.
With a scanner, it's counting misfires on all 8 cylinders at idle and light throttle. A few easy things like clean injectors and throttle body.
Any ideas?
Most obvious during light throttle and torque converter locked.
With a scanner, it's counting misfires on all 8 cylinders at idle and light throttle. A few easy things like clean injectors and throttle body.
Any ideas?
LS1Tech Sponsor
Joined: Dec 2005
Posts: 2,932
Likes: 12
From: CT
Check coils, spark plugs, plug wires... Make sure plugs fully installed... Make sure no cracked ceramics on any plugs... Make sure plug wires are fully snapped on to plugs & coils (have had people before find that plug wires have slipped off, or even plugs themselves have loosened up and come out)... ----- Also, get a can of CRC Mass Airflow Sensor Cleaner and clean the MAF sensor, and make sure it's re-installed facing the correct direction...
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06MonteSS / DiabLew Tune
2014 Camaro 2SS/RS - LS3, 6-speed manual, short-throw performance shifter, NPP dual-mode performance exhaust, 1LE front splitter, ZL1 rockers, Z28 Rear Spoiler, all paint-matched Red Rock Metallic, BMR strut tower brace, Cold Air Inductions cold air intake, Apex Motorsports, Inc. catch-can, Custom DiabLew Tune
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06MonteSS / DiabLew Tune
2014 Camaro 2SS/RS - LS3, 6-speed manual, short-throw performance shifter, NPP dual-mode performance exhaust, 1LE front splitter, ZL1 rockers, Z28 Rear Spoiler, all paint-matched Red Rock Metallic, BMR strut tower brace, Cold Air Inductions cold air intake, Apex Motorsports, Inc. catch-can, Custom DiabLew Tune
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com
Thread Starter
Staging Lane
Joined: Apr 2018
Posts: 91
Likes: 14
Any way to diagnose without just trying intake gaskets or o2?
I'm pretty confident it is not ignition related. The car ran good, then suddenly misfiring. I don't think the MAF can be installed backwards on these cars. On the scanner it's randomly any one of eight cylinders. I suspect a plug, coil or wire would be a bigger number on a particular cylinder. This is random on all 8.
I also reluctantly changed all 8 spark plugs even though they only had 30,000km. No change.
I'm pretty confident it is not ignition related. The car ran good, then suddenly misfiring. I don't think the MAF can be installed backwards on these cars. On the scanner it's randomly any one of eight cylinders. I suspect a plug, coil or wire would be a bigger number on a particular cylinder. This is random on all 8.
I also reluctantly changed all 8 spark plugs even though they only had 30,000km. No change.
TECH Enthusiast
Joined: Jul 2018
Posts: 635
Likes: 329
From: Missouri
i kinda think your right (about the ignition working) thats why i suggested things that effect all cylinders that ive seen do stupid things like your describing . and on a ls is very simple to do i can do intake gaskets in under 45 min and 02s in 20 min or less. have you checked fuel pressure? or spray carb cleaner around intake to check for a possible leak? any loose hoses? map sensor grommet sealed good? any thing look rodent chewed up? obviously were shooting from the hip here with not alot of info to go off of. just trying to give you some ideas.
Thread Starter
Staging Lane
Joined: Apr 2018
Posts: 91
Likes: 14
Good call Kjd on the O2 sensor.
There was no o2 codes and the scanner was showing activity but on the fact they were original. Threw in 2 new ones and the activity is more pronounced and the big news is no more misfires.
There was no o2 codes and the scanner was showing activity but on the fact they were original. Threw in 2 new ones and the activity is more pronounced and the big news is no more misfires.
