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Engine backfiring and the check engine light is blinking and the traction control and stablilitrack warnings are on?

Tiny
TJVAN518
  • MEMBER
  • 2012 CHEVROLET 1500
  • 4.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 153,000 MILES
I recently rebuilt the bottom end in the truck. I purchased it from a guy at my father in laws work. The truck keeps stuttering like it’s going to stall out. The MAF sensor will read right after I unplug battery and reset computer but after it starts sputtering the MAF sensor won’t register. Also I read online that the throttle body might need cleaned so I sprayed throttle body cleaner and now it’s barley running and sounds like it’s backfiring and the check engine light is blinking and the traction control and stablilitrack warnings are on. I can’t figure out what it is. And I’m scared to drive it to get codes checked with check engine light blinking.
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Saturday, March 27th, 2021 AT 5:15 PM

25 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

If the check engine light is blinking, that indicates at least one cylinder is misfiring.

As far as the MAF, have you replaced it? The MAF incorporates the IAT (intake air temperature sensor). Also, have you checked the air intake tube where it mounts to the throttle body? There were issues with them cracking and allowing unmetered air to enter the engine. See pic 1 below.

Next, if you sprayed a lot of throttle body cleaner into it, that could have caused issues for the spark plugs. Also, when you open the throttle plate by hand, you have to perform an idle relearn procedure.

Do me a favor, take a look through the manuals directions for cleaning the throttle body. (See pic 2 below). Pay attention to what I highlighted and check the product you used.

If you look at pic 3, it explains the idle relearn procedure.

The last recommendation I have is to remove the spark plugs and make sure they are good. If you sprayed a lot of throttle body cleaner into the throttle body, the plugs could be fouled or have dirt on them preventing spark.

___________________________

Let me know what you find or if you have other questions.

Take care.

Joe
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Saturday, March 27th, 2021 AT 9:19 PM
Tiny
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So I went out this morning and started it and it’s not sputtering now. Kind of wondering if because the engine is cold now. But I tried to do the high idle and it didn’t change the idle but the idle isn’t high. Also the check engine light isn’t on anymore and the truck seems to be idling fine While it’s cold. As writing this I let it warm up and sit for awhile and after about ten minutes the idle drops slightly and you can feel it shake and smell gas but no check engine light. What might this be seeing how it’s not backfiring anymore and there is no light?
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Sunday, March 28th, 2021 AT 6:13 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
Where are you smelling gas? Does it seem like it's running rich or do you smell it from a different place? It could be an issue with the EVAP system causing a vacuum leak.

Do me a favor. Check the EVAP purge solenoid. I attached two pics below to help you locate it. Check the line to and from it. Make sure nothing is disconnected or damaged. When that solenoid opens, it allows fuel vapor to enter through the intake. It comes from the charcoal canister. The solenoid itself may be damaged causing a vacuum leak (lowering RPMs) and the fuel smell.

If that isn't the issue and you have a live data scan tool, check the short-term fuel trims and let me know what they are. Do this when the engine is at idle and you feel it shaking.

I will watch for your reply.

Joe
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Sunday, March 28th, 2021 AT 7:53 PM
Tiny
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I’ll check that! Do you think it might be the charcoal canister? I also noticed that I have a hard time filling it with gas because it’s not venting properly it takes forever to fill up because I can’t hold it open all the way it keeps stopping like it’s full. I saw online that they get plugged up.
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Monday, March 29th, 2021 AT 7:03 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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I found an interesting technical service bulletin you may find of interest. It deals with the fuel tank slow filling.

See the pics below and let me know if you feel this could be relevant.

Joe
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Monday, March 29th, 2021 AT 7:08 PM
Tiny
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I’ll check on that! I got a code reader and it said P0300 which would be random misfire. I got light to go off and I drove it down road. I made it like 3 miles then stopped at stop sign and I could feel it shake. So I took off and it was sputtering and sounding like it was backfiring but not out of the exhaust and then it just started running fine and worked fine the rest of way home.
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Wednesday, March 31st, 2021 AT 7:28 AM
Tiny
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And also I put a fuel pressure gauge on it and the needle was jumping crazy between 60-63 not sure if that would have something to do with it.
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Wednesday, March 31st, 2021 AT 7:28 AM
Tiny
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Does the scan tool you have provide live data? If it does, can you check the short-term fuel trims and let me know what they are? Also, is there any smoke coming from the exhaust?

Joe
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Wednesday, March 31st, 2021 AT 5:54 PM
Tiny
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No it doesn’t have live data and I don’t believe so besides when it was cold outside.
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Thursday, April 1st, 2021 AT 10:40 AM
Tiny
JACOBANDNICKOLAS
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Okay, that makes it a little more difficult. Do me a favor. The next time it starts making the noise that sounds like a backfire, record it and upload it for me to hear. Without a code or data, it makes it difficult. I hope you understand.

Have you done anything with the crankshaft position sensor?

Joe
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Thursday, April 1st, 2021 AT 6:32 PM
Tiny
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Update: I tried driving it to rest the permanent codes and I got about 5 miles down the rode and I lost power while driving and the exhaust got really loud. It stalled out on side of road. I could not get it to start and when it did I’d would barley run and there would be white smoke puffing out of exhaust. Then I let it sit and it was like it came back to life drove about 100 yards down road and it stalled again. I hooked code reader up and it came up P0122, P0123 and P0223. I let it sit a little but longer and it started up again but the exhaust was really loud for the amount of pedal I was pushing and it sounded like something was rattling was rattling. I just let it sit and going to go back in a while and see if that makes a difference.
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Friday, April 2nd, 2021 AT 11:48 AM
Tiny
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I went back and those codes went away, but I got new codes P0011 and P0443 and then the engine sounds like this and it quit running right after.
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Friday, April 2nd, 2021 AT 3:36 PM
Tiny
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Another video.
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Friday, April 2nd, 2021 AT 3:37 PM
Tiny
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Hi,

In the first video, it sounds like an exhaust leak. I can't identify anything in the second.

Interestingly, the codes that went away are opposites. One indicates throttle position sensor low voltage and the other indicates throttle position sensor high voltage.

The 443 is related to the purge solenoid. I asked about that earlier. Are you certain it is working?

Last, you mentioned white smoke. How much was there? Is the engine coolant going down? White smoke usually indicates engine coolant is getting into the combustion chamber. Here is a link that explains how to check for head gasket issues:

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know what you find. Also, take a rubber mallet and tap around the catalytic converters to see if that could have been what you heard rattling. If one is loose inside, that certainly causes a power loss and odd sound.

Joe
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Friday, April 2nd, 2021 AT 6:59 PM
Tiny
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So now I figured out that the catalytic converter on driver side was broken so had them replaced and pulled plugs and the driver side were flooded while the passenger side wasn’t. The check engine light is still flashing.
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Tuesday, April 13th, 2021 AT 3:18 PM
Tiny
JACOBANDNICKOLAS
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Were the plugs replaced? The idea that they were flooded sort of makes sense. If there was an exhaust leak as described, that could have caused the sensors to think there was a lean mixture. In that case, the computer would have been adding fuel to compensate.

Let me know if the plugs were replaced. Also, what code is present?

Joe
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Tuesday, April 13th, 2021 AT 6:33 PM
Tiny
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Well, the passenger side is dry that’s why I was confused. And I read online that the upstream 02 sensor would cause one side of plugs to be wet and the other not. And the side that is wet is the side of the cat converter that was broken. And the plugs were replaced when the engine was put back in. And the codes are Po300 and Po443 also I haven't replaces that evap solenoid but when I unplug it the truck doesn’t do anything. Does that mean that is bad?
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Wednesday, April 14th, 2021 AT 7:21 AM
Tiny
JACOBANDNICKOLAS
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Hi,

As far as the purge solenoid, you can't check it that way. You need to confirm power to it (using a scan tool that can actuate) and you check resistance in the actuator.

If you look at the attachments, I included the diagnostics and tests for the purge solenoid. Take a look through them and see if it is something you feel comfortable doing. If you need additional information, let me know.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find.

Joe
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Wednesday, April 14th, 2021 AT 6:58 PM
Tiny
TJVAN518
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Okay, so I found that there was a broken ground on the driver side lower end of engine so repaired that and solved my problem. But then I drove up road and back and noticed when I got back and stopped that it lost oil pressure and the top end started ticking like before I change oil sending unit, high pressure oil pump, and new crank and bearings. Wondering if because it sat and the engine was dirty maybe the oil filter is now clogged up. Only reason I shape that is cause after the top end started ticking I shut it back of and minute later started it back up and oil pressure was fine at idle.
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Sunday, May 2nd, 2021 AT 12:53 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

That is odd. You mentioned earlier that there was white smoke. If you check the engine oil, is it clean, full, and no evidence that coolant is mixing with it? Also, does it smell like gas could be mixing with it?

As far as dirt in the engine, if you replaced the oil pump, I have to assume the pick-up tube in the oil pan was checked to make sure it was clean, correct? And where the pick-up tube attaches to the pump was properly secured, correct?

See pic below for the two areas I'm questioning.

Let me know.

Joe
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Sunday, May 2nd, 2021 AT 5:53 PM

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