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Hello I'm new on here, I hope yall can help me out. I have a 2015 GMC 3500HD 6.0l gas. I recently bought it and then noticed that when in idle it began to run rough and I can give it some gas and at times it will go but very slowly and sluggish then it will pop and start running better or it will shut off at times. I was thinking it was the cats and when I took it to shop,I had them do a complete scan and they found PIP5644 with four o2 sensors bulletin. It just acts weird, I cleaned all ground wires,used a can of seafoam on intake and one in fuel tank, changed all spark plugs and O2 sensor bank 2 sensor 2 since that was the only fault I had at first. I can't seem to find any air leaks but I did noticed that when purging valve comes on truck runs a lil rough and also noticed lights dimming down at the same time. I checked all battery cables and found them to be loose, so I tighten them and also checked purging valve and seems to be working fine, I'm completely lost on this one any taught or advice I would really appreciate it.
I would clean the Throttle Body first. Throw a new fuel filter on for $12. Then check the fuel pressure. Could also be the Mass Air Flow Sensor. But you should be able to read any codes with an OBD2 reader, get one if you don’t have one. The cats can cause this. Check your exhaust and see how hot it is. If it’s super (burn the hair off your skin) hot then it’s the cat’s.
 

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Discussion Starter · #22 ·
I would clean the Throttle Body first. Throw a new fuel filter on for $12. Then check the fuel pressure. Could also be the Mass Air Flow Sensor. But you should be able to read any codes with an OBD2 reader, get one if you don’t have one. The cats can cause this. Check your exhaust and see how hot it is. If it’s super (burn the hair off your skin) hot then it’s the cat’s.
Hello Will Mann, thanks for your response. I have checked MAF, throttle, harness,ECM connections,changed out O2sensors,checked for vacuum leaks, all good so far ,haven't found anything. The cats seem to be working just fine, I didn't put a temp gun but I feel no restriction, I did pull o2 sensors out and put a camera and saw no damaged. I do have a code reader and it only shows that two codes are stuck P013d and P2272 and even when I switch the connectors on the two o2 sensors after the cats it still shows same codes,I taughtbit would move over the other bank same principle as moving coils to find missfire and it didn't. So that makes me think it's an issue with the ECM but chevy house wants to troubleshoot all codes before they can update/ refresh ECM, what are your taughts? Oh and I haven't changed fuel filter ,I will do that sometime today and I'm going to kick my self if thats all it is, just the o2 sensor issue it's driving me nuts.
 

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Hello Will Mann, thanks for your response. I have checked MAF, throttle, harness,ECM connections,changed out O2sensors,checked for vacuum leaks, all good so far ,haven't found anything. The cats seem to be working just fine, I didn't put a temp gun but I feel no restriction, I did pull o2 sensors out and put a camera and saw no damaged. I do have a code reader and it only shows that two codes are stuck P013d and P2272 and even when I switch the connectors on the two o2 sensors after the cats it still shows same codes,I taughtbit would move over the other bank same principle as moving coils to find missfire and it didn't. So that makes me think it's an issue with the ECM but chevy house wants to troubleshoot all codes before they can update/ refresh ECM, what are your taughts? Oh and I haven't changed fuel filter ,I will do that sometime today and I'm going to kick my self if thats all it is, just the o2 sensor issue it's driving me nuts.
It could be fuel pump but if so you should be seeing lean on both banks 1 & 2 but stranger things have happened. Fuel pressure check is a must at this point. I’ve seen them go and only throw a lean code until your stuck on the road somewhere. fuel filter is quick and easy, it’s good maintenance and you will want/need to replace it anyway if it turns out to be the fuel pump. Hope it’s not they’re a pain in the ass on those trucks, especially if the tank is full. I always syphon pump the gas into another vehicle as opposed to a bunch of 5 gal cans. As for the ECM, you are at the dealerships mercy unless you know of a shop with an expensive bidirectional OBD2 unit with someone that knows what they doing. There are a lot of tests that you can run that your cheap units just can’t do, also everyone will tell you check the grounding wires throughout. I have a feeling that it’s the fuel filter or pump. Pressure checking gauges are not very expensive and a must to have when you do your own work. Your going to want to connect it and turn the key without starting the truck, just off the top of my head you’re looking for 50 to 60 psi. I remember putting a new one in and having it go out a week later. I put the pressure gauge on it and it read 9 psi. Don’t replace it with a cheap pump if it needs replaced.
 

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Discussion Starter · #25 ·
Thank you for the input, I will recheck fuel pressure and injectors. As for the fuel filter, either in blind or its just part of the fuel pump assembly, I followed fuel line from tank to fuel rail and didn't see one.
 

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Thank you for the input, I will recheck fuel pressure and injectors. As for the fuel filter, either in blind or its just part of the fuel pump assembly, I followed fuel line from tank to fuel rail and didn't see one.
Your right, I see that the fuel filter can be a bitch on those trucks, it’s usually in the lower engine compartment, so I’d check the fuel pressure. When my fuel pump went it did the exact same thing. It would start cold idle would get rough and die. If I waited 10-15 minutes it would start and do the exact same thin. I had to wait 10 - 15 minutes before it would start again and then die. It would not start unless I let the pressure build just enough to get it to start but would quickly starve and die. If it passes the pressure test then the natural progression would indicate the fuel rail and injectors, testing them out is not difficult just a little time consuming. The ECM is a long shot.
 

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Thank you for the input, I will recheck fuel pressure and injectors. As for the fuel filter, either in blind or its just part of the fuel pump assembly, I followed fuel line from tank to fuel rail and didn't see one.
fuel filter is in the fuel pump assy... 2002 GM trucks around that year filter in the fuel tank..
my 2000 ext filter replace it 40K miles..
 

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Discussion Starter · #28 ·
fuel filter is in the fuel pump assy... 2002 GM trucks around that year filter in the fuel tank..
my 2000 ext filter replace it 40K miles..
Yes sir, thank you I have looked and looked and figured it be in the tank. So I'm going to test injectors and then re-check fuel pressure and see where I'm at. Just gotta try and finish some of the million other things I have going on. I will post my findings, thank you all.
 

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fuel filter is in the fuel pump assy... 2002 GM trucks around that year filter in the fuel tank..
my 2000 ext filter replace it 40K miles..
Yes, I have a 2003 Avalanche and thank god it’s easy to get to, it’s and in-line filter right under the side rail on the right side. I did look and see that that truck the filter is in the pump assembly which is the stupidest place to put it. The with diesel engines it’s in the engine bay and you got to go through the wheel well to get to it. Which is why I keep an assortment of body and trim clips, bumper push fasteners and rivet clips and various screw sizes. i also have fuel pressure tester gauge that I can use inline or connect to the fuel line as an end point. I modified the line so I can slap it on there easily. I always start my vehicles by turning the switch and waiting 10 to 20 seconds before turning it over to let the system pressurize. I also keep a Wifi obd2 reader connected so I can see real time transmission temperature through an old iPhone 6 used just for that. Because when it says the ”transmission hot” it means the transmission is toast. I just bought a beater car 2007 Buick Malibu, the engine runs great, I’m putting new rear bearings on tomorrow. The previous owner had front bearings and ball joints done a few years ago.
 

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Yes sir, thank you I have looked and looked and figured it be in the tank. So I'm going to test injectors and then re-check fuel pressure and see where I'm at. Just gotta try and finish some of the million other things I have going on. I will post my findings, thank you all.

I have an identical concern to your 2015 6.0, runs rough at idle with all 4 O2 sensor codes. What was the cure for your problem? Thanks in advance.
 

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If you have codes for all four sensors, you could have lost power to the heaters, I think they all share a fuse.
Of course I'm guess at that, what codes are you getting, heater codes, or performance codes?
 

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Voltage stuck high and voltage stuck low. When the concern happens you can watch 2, 4, 6, and 8 cylinder miss fire but sometimes it's all 8 cylinders. Long term fuel trims are -30 both banks. Van only has 38k miles on it, fuel pressure is good, spark is good, volumetric efficiency is 89% (good), cleaned the MAF. Idk what else it could be I'm not to familiar with Chevy.
 

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Well they tell a story.
There is nothing wrong with to O2 sensors, they are just doing their job and reporting what they see.
Your problem is the engine is running too rich.
You have leaking/dirty injectors, or a dirty throttle body.
If it's injectors, the engine is getting too much fuel, if it's the throttle body, the engine isn't getting enough air.
The P0300 is a random mis-fire code, it will do that if the mix isn't correct
 

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P0137, P0152, P0157, P0175, P0300, and P0506.
the IAC idle control valve in the throttle body .. take it out and clean it and clean the internal ports .. the engine has a lean condition and the idle speed is lower p0506 ... also check and clean the MAF .. look up to clean the MAF .. using the MAF cleaner and clean the IAC / port holes..
 

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Nice!!!!
 
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