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Hey yall! New member here, sorry for creating a thread so early on, but my warranty expiration is creeping up on me fast and I need to get this sorted- so here's my issue.

 

I have a 2015 2500HD with the 6.0 and about 95,000mi, and for the past 6 months, I've been having this issue where It'd start pulling timing ( up to 15 degrees of KR) under moderate to heavy throttle, as soon as it hits 3000RPM. There is no audible knock, but 15 degrees of KR sounds very excessive. Higher octane fuel makes the issue better,  and usually after long interstate drives (no heatsoak), it runs great, but generally, it's very bad. Towing a 32FT trailer full of band equipment up a mild hill, it struggles to get out of first gear, and slams into the next gear because the timing is so far retarded before the shift, that it screws with the shift timing.  I have used various fuel system cleaners ( now trying Amsoil Pi, as I know its well proven ) but so far, none have made any difference. I want to check the fuel pressure, but I don't see a test port, and I can't get any OBD app to display fuel pressure.

 

Here's what confuses me:  Sometimes, under the same conditions, It'll run just fine and pull hard straight through 3000 RPM. The only thing I can find different between the times that it runs like a POS and times that it runs like its brand new, is that when it's running like crap, it shudders at idle- enough to be felt throughout the entire truck.

 

It pulls the most timing at around 3000, and tapers down as the revs increase.

 

I got it used, with about 76,000mi, so I'm not clear about its past. Back when it was running horribly I was considering that It might have been tuned by the previous owner, but lately, its been randomly running just fine. 

Its been fine for the past week or so, but I'm still very curious about what could be going on. 

 

I have TorquePRO recordings of the issue happening, which I may upload later if that would be of any help. I've been hoping for a CEL but of course- no pending or stored codes!

 

Thank you all! Sorry for the length of the post!

Edited by Abarth500.
added a bit about the lack of CEL
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  • 2 weeks later...
8 hours ago, avalonandl said:

Tune it with a Diablo Sport. 

 

There is a schrader valve somewhere on the fuel rail.

I got a fuel pressure test kit, expecting to see a Schrader valve sitting on the rail and there wasn't one! Possibly it's further down near the tank since it's return less ans has a PWM controlled pump. I'll have to look again I guess.

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  • 1 year later...
  • 5 months later...

Wow. It's been a long time.  The primary driver of the truck drives it so calmly that the issue doesn't really bother him, and with me constantly running into dead ends I guess I just got discouraged and gave up on the issue...until now.

 

So here's where I am. It has the e78 PCM of course, and it seems a lot of local tuners don't really want to touch all of this torque based stuff, understandable, but it's stopped me from finding any local help. I've done some logs, but I wouldn't say they have been very helpful for me at least, and with few people wanting to look into it, it hasn't yielded much. 

 

The issue is very much still there, same behavior as before. Just thought i'd give an update since I left this thread dead in the water before.

 

Also fun fact, there is no schrader valve on the fuel rail for whatever reason. To test fuel pressure I had to hook up an adapter on the fuel line that teed into both the gauge and the rail. Weird. 

 

 

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Look into a VXDIAG NANO with GDS software so you can see everything and run proper tests.  Could be loose heat shield or something that knock sensors are picking up.  Good scan tool can read fuel pressure and commanded fuel pressure.  Maybe even your Torque Pro App if you get the right PIDs.  Ask Ken, KBUSKILL over at the TahoeYukon Forum.  Some guys here might know too.

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On 6/12/2020 at 1:23 AM, swathdiver said:

Look into a VXDIAG NANO with GDS software so you can see everything and run proper tests.  Could be loose heat shield or something that knock sensors are picking up.  Good scan tool can read fuel pressure and commanded fuel pressure.  Maybe even your Torque Pro App if you get the right PIDs.  Ask Ken, KBUSKILL over at the TahoeYukon Forum.  Some guys here might know too.

Great, thank you for pointing me in the right direction. Looking into software, it seems you kind of have to go all or nothing with this platform if you want to do proper logging. It's a shame there aren't any $50 phone apps that can do it all, like I've found on other platforms. 

 

 

Looking into VXDIAG, also trying the software that came with my OBDLink MX. 

 

Any pointers on the specific parameters i should log to give data to the people trying to help out?

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11 hours ago, Abarth500. said:

Great, thank you for pointing me in the right direction. Looking into software, it seems you kind of have to go all or nothing with this platform if you want to do proper logging. It's a shame there aren't any $50 phone apps that can do it all, like I've found on other platforms. 

 

Looking into VXDIAG, also trying the software that came with my OBDLink MX. 

 

Any pointers on the specific parameters i should log to give data to the people trying to help out?

Well Torque Pro and there's another whose name I forget can see a lot of engine functions if you get the PIDs set up for them.  I would want to see the fuel pressure, actual and commanded, the O2 sensors and Long Term Fuel Trims, Spark Advance and all ****** options.

 

If yours were mine, I'd get the MDI2 with GDS2 software so I could see and test everything.

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Well, after complaining about it I just sucked it up and purchased VCM Suite- it gets here Friday. I'll be sure to have some logs up by the end of the weekend.

 

I was looking into other options but as the price started to creep higher, I figured I may as well just get HPT and be done with it. Not backing down from fixing the issue this time :cheers:

 

Thanks for the help so far y'all, sorry it too me so long to suck it up and invest in something.

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Hi yall, here's a log, along with the config and tune.

 

I've been having a hard time getting the truck to act up like it has for the past 40,000mi (of course), so this isn't a great example of "hitting a wall" but still, lots of KR can be seen near the end of the log, with TPS steady. 

 

Thanks!

we did it 6.hpl Default 2.Channels.xml Original ECM TCM.hpt

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On 6/20/2020 at 6:28 PM, Abarth500. said:

Hi yall, here's a log, along with the config and tune.

 

I've been having a hard time getting the truck to act up like it has for the past 40,000mi (of course), so this isn't a great example of "hitting a wall" but still, lots of KR can be seen near the end of the log, with TPS steady. 

 

Thanks!

we did it 6.hpl 148.75 kB · 3 downloads Default 2.Channels.xml 1.97 kB · 3 downloads Original ECM TCM.hpt 1.82 MB · 4 downloads

Not able to view any of this, how about some screen shots?

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