I just bought a 2019 Suburban Z71 5.3 w/AFM. I have a rough idle, but no stalling and it runs pretty good otherwise. No codes and idle is ~500 rpms and steady, not moving around. No misfires on scanner. All the plugs and wires are well connected. I have replaced air filter which was in bad shape. I pulled the MAF and cleaned it well. I pulled the throttle body and cleaned it. It wasn’t bad at all. I’m about to do 2nd tank of fuel system cleaner. My MPG is what it should be. I’ve been driving in L5 to prevent AFM. I plan on deleting AFM, just haven’t figured out which way to do it yet. I’m scratching my head. I ran across old TSB about motor mounts. Any ideas?
2019 5.3 Suburban Rough idle at stop No Codes Run good though
- Thread starter Cut Wagon
- Start date
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Blackcar
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What's mileage on your vehicle.
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When you accelerate, are there any stutters or misfires? Or, is the misfire only at idle?
I only notice it at idle, either in P or D. Runs clean on acceleration and I don’t feel a miss. Now I have had vehicles have misfires while it “feels” clean to me. Sometimes hard to feel slight miss with 8 cylinders.
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Are you using a quality bi-directional scanner when you look for codes, or are you using an under $50 scanner to look for codes?
what scanner are you using? i'm asking because some live data may show more detailed data, a "misfire" technically can start happening before any codes are set.
Isn't this pretty common because of the low idle rpm? Read a lot about it when we got our 15. I picked up a cheap diablo tuner bumped the idle up 100 rpm, if I remember correctly, and it idles smooth as butter ever since.
Forgot to say that my friend with expensive diagnostic tool raised my idle to 700 and while it was slightly better sitting in driveway, as soon as he unplugged and I drove away, it went back to 500 and rough idle.
fozzi58
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Could be the notorious torque converter stutter. I never personally experienced that but many on this forum have.
How about plugs and wires? My TA sits in the garage a lot and while it doesn't get a lot of mileage, as soon as the idle starts to roughen up I usually do plugs and wires and that cures it.
How about plugs and wires? My TA sits in the garage a lot and while it doesn't get a lot of mileage, as soon as the idle starts to roughen up I usually do plugs and wires and that cures it.
if everything is working properly there should be no need to "raise the idle"
on these direct injection engines they need a good cleaning done by 100k at the most, and injector cleaner added every 2-3 months won't hurt.
the injectors fail also, more often than previous generations, you will see it happening on cold starts and monitoring misfire data (which may not throw a code) until a certain threshold is met, but you will feel it performance wise.
look at the live misfire data, normal operation should 0 (cylinders 1~8) almost always with very few random counts if any at all.
the computer monitors this data and will only throw a misfire code if a specific amount of misfires is counted, otherwise it just runs like crap with no codes
you gotta dig for it.... maf data, o2 sensor data, injector data, coil data, fuel pressure........
clean the maf and throttle body on a regular basis
02 sensor rated life is 100k same as plugs & wires.
on these direct injection engines they need a good cleaning done by 100k at the most, and injector cleaner added every 2-3 months won't hurt.
the injectors fail also, more often than previous generations, you will see it happening on cold starts and monitoring misfire data (which may not throw a code) until a certain threshold is met, but you will feel it performance wise.
look at the live misfire data, normal operation should 0 (cylinders 1~8) almost always with very few random counts if any at all.
the computer monitors this data and will only throw a misfire code if a specific amount of misfires is counted, otherwise it just runs like crap with no codes
you gotta dig for it.... maf data, o2 sensor data, injector data, coil data, fuel pressure........
clean the maf and throttle body on a regular basis
02 sensor rated life is 100k same as plugs & wires.
With Direct Injection, I suggest a bottle/can of BG44K Fuel System Cleaner to you fuel tank.
How long has it been since the valves were cleaned?
