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6.2 popping on cold starts

country_09

By country_09
in Engines & Drivetrain

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country_09 Enthusiast

country_09

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Little background, truck is a 14 6.2 with headers/ory to a 22" magnaflow, airaid Tube with k&n filter, and khp tune. When the truck sits over night or through the day, basically its first cold start, I get this popping from the exhaust, clear as day comes from there and out back to the 5" tip I have. It only does it for 10 seconds maybe, some days it's worse than others, but it throws a code for rough engine idle, even though nothing's wrong. I can't seem to find anything on it. I don't think it's tune related but hell it may be, it did it stock too with all the stock exhaust, but it never did it bad enough to throw a code. Now it's just annoyin. I changed the plus/wires, cleaned the MAF and throttle body just to see. Kinda grabbin at straws here...any help is appreciated

country_09 Enthusiast

country_09

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Tried to get one today when I left for work about 4:15 but it didn't do it. Only thing I noticed different was that the temp outside was hotter than it has been and I let it sit all day instead of startin it once I woke up around 10-11 coming off nights. Will see if I can't get one tomorrow

country_09 Enthusiast

country_09

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th_EA347B0C-6332-4C83-A2E8-74390E1285FE_

 

Ok so it did it this mornin. Can't really hear it but there is a poppin noise a couple times in there

Willshire Enthusiast

Willshire

Posted
Posted

I hear it. Lean Misfire? So...you took out all of the cats and put headers/ory on? How does the truck know if it's in a lean/rich condition if it has no sensor data to make adjustments? If you plug in dummy O2s, are they designed to switch above and below 500mV like an O2 sensor does? Based on MAF, TPS, O2's the ecm leans or enriches the fuel mixture. You have removed one of these components so data collection and adjustment may be flawed and on a cold engine may create a lean misfire. But, not enough for a code. If your programmer can read data, put it on misfire and see if you are getting any. ECM has to see 5 in a row i think to set the SES light.

 

You say it happened on the stock exhaust too? Was it tuned or was that without a tune?

country_09 Enthusiast

country_09

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I wanna say it happened on the stock exhaust, but I can't be for sure since it was so quiet and with the baffle in there it never made an audible poppin noise. And it never threw a code for the rough engine idle. But since I've added the headers, y-pipe that took the cats out, and magnaflow it's noticeable. I did remove the rear o2 sensors, the fronts stayed the same and it is tuned now. It wasn't before I did any exhaust work. Now when it pops, it'll throw the code, truck runs great, just the poppin on cold starts and that's what I'm tryin to figure out. My buddy has hptuners on his laptop so I'm sure I could get him to look at it, but duplicatin the poppin is hit and miss, and never happens after its ran once that day

  • 1 month later...
morrislee Enthusiast

morrislee

Posted
Posted

get a bluetooth OBD 2 reader with Torque and monitor misfires. if you get any misfires, it is going to be consistantly over 10-20 misfires. anything from 2-4 that shows up every now and then should not be an issue.

 

saw your post here, http://www.performancetrucks.net/forums/gmt-k2xx-trucks-general-discussion-221/p050d-code-533167/page2/

 

keep the code on, dont wipe it off, find a good dealer to fix it. the dealer finally fixed my issue did not mention anything against my oil catch can, cold air intake, and magnaflow exhaust

TJay74 Senior Enthusiast

TJay74

Posted
Posted

I seriously doubt the front O2 sensors were removed, those are the only ones the ECM uses for fueling changes. The rear O2 sensors only tell the ECM if the catalytic converters are working.

country_09 Enthusiast

country_09

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I didn't wanna take it t the dealer due to headers and the tune, they'd turn me away in a heartbeat which I guess is the chance I took when installin them lol. Front o2 sensors are in of course, rears were deleted. Now I've changed plugs and wires, poppin has substantially minimized with that and I'm thinkin the wires were no good as all plugs look great but changed em anyways. Now it does have slight pops, but sounds more like a rumble I guess. I did get a flashing light this mornin but didn't have time to check it as I was goin to work so I drove my wife's car. Last time it flashed I got cylinder 1 misfire iirc. Only problem is the truck runs with no issues at idle, it's when I'm gainin speed. Not floored, but just easing into the throttle it feels like the truck jerks or hesitates. I've been researching and leaning towards a bad coil pack and im Guessin it's safe to assume it's cylinder 1? Anyone else think it could be somethin else? Injector maybe?

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