2018 high country surging

[Chad541121]

I am attaching 4 hp tuner files. I have a customer complaining of surging amongst other things. He presented me with these files to help diagnose.
I have a good understanding of cars but reading these files, I'm struggling to come to a conclusion.

2018 High Country with 36k miles on it. Whipple charger was added at 10k along with long tube headers, stage 2 kit, and underdrive pulley according to customer.
Was tuned and drove great for 20k miles. Problem seemed to happen overnight.
Transmission has since been rebuilt, with high performance torque converter and then back to factory torque convertor. Customer stated it made no difference with this issue.
He has replaced the throttle body.

I'm seeing lots of fluctuation in fuel pressure and STFT. Maybe someone with more experience can notice the issue easily.

Thanks in advance.

test drive 1 - 7-8-23 245 pm.hpl
test 2.hpl
test 3 305 pm.hpl
test 4 310 pm.hpl

[jake 03]

If it still has the original stock in tank fuel pump I would take a good hard look at it. I've seen a lot of them start causing fuel supply issues right around 36k

[Chad541121]

That?s what I was trying to determine. From what I can find, pressure should range from 46-84 which seems very broad. Can it be determined by these files that the fuel pump is at fault?

[jake 03]

Seems like they start having issues once it drops below 40 psi on the supply side. I can't view the logs until I get back to my laptop

[cadillactech]

Have them log with this channel list.

E92 V8.Channels.xml

[Chad541121]

Customer will get the new tests with those channels. I?ll post back when I get them

[Chad541121]

Have them log with this channel list.

E92 V8.Channels.xml

Here is the new test.

test 7-13-23.hpl

[Chad541121]

Have them log with this channel list.

E92 V8.Channels.xml

steady rpms - 7-13-23.hpl

I asked for this file also. Hoping to see more steady fuel pressures. Seems like they are all over the place.

[cadillactech]

Doesn't look like you used my channel list but its not a big deal, there isn't much available to log on the ECM anyway after plugging in your log to my scanner.

Low side fuel pressure always looks choppy, but your high side looks ok. As load increases so does the rail pressure, can't see desired but I don't see that being your surge.

Long term fuel trims are turned off but your short term trims at idle are over 20% and they get pretty high under some driving conditions. This would indicate some kind of vacuum leak possibly, and with the Whipple, there are multiple leak points that could be possible.

Has anyone smoke tested the intake to make sure there are not any vacuum leaks? Seems likely that could be a possible issue.

I would also rule out a misfire from a burned plug wire on a header, spark plugs being worn, etc.

Can you read the calibration and post it? It being a Whipple it may not be able to be read but its worth a shot. Whipple tunes are know to be really crappy as well so that could explain it, even if the customer has been living with it for 20K miles.

[Chad541121]

Doesn't look like you used my channel list but its not a big deal, there isn't much available to log on the ECM anyway after plugging in your log to my scanner.

Low side fuel pressure always looks choppy, but your high side looks ok. As load increases so does the rail pressure, can't see desired but I don't see that being your surge.

Long term fuel trims are turned off but your short term trims at idle are over 20% and they get pretty high under some driving conditions. This would indicate some kind of vacuum leak possibly, and with the Whipple, there are multiple leak points that could be possible.

Has anyone smoke tested the intake to make sure there are not any vacuum leaks? Seems likely that could be a possible issue.

I would also rule out a misfire from a burned plug wire on a header, spark plugs being worn, etc.

Can you read the calibration and post it? It being a Whipple it may not be able to be read but its worth a shot. Whipple tunes are know to be really crappy as well so that could explain it, even if the customer has been living with it for 20K miles.

I apologize. I briefly looked at this truck and then scheduled it back in a few weeks once I had time to figure something out. The customer must not have understood my instructions on using the channel list.
I agree It looks like a vacuum leak. I am not familiar with supercharger tunes. Wasn't sure if the STFT numbers were related to a tune or not. I did notice the LTFT was not showing. Why would that be turned off? I sent instructions directly from the HP Tuners site to the customer to retrieve the calibration file. I'm interested in learning something here myself. Thanks for you time.

I will post back once he provides me with the file.

[cadillactech]

I apologize. I briefly looked at this truck and then scheduled it back in a few weeks once I had time to figure something out. The customer must not have understood my instructions on using the channel list.
I agree It looks like a vacuum leak. I am not familiar with supercharger tunes. Wasn't sure if the STFT numbers were related to a tune or not. I did notice the LTFT was not showing. Why would that be turned off? I sent instructions directly from the HP Tuners site to the customer to retrieve the calibration file. I'm interested in learning something here myself. Thanks for you time.

I will post back once he provides me with the file.

Some people will turn off LTFT, some won't. Unless the setup is radical I will keep them on but sometimes they need to be turned off as they skew things fueling wise.

I would exhaust any mechanical concerns like a vacuum leak, misfire underload, etc. first so you don't end chasing your tail but a file would be helpful. It is unfortunate that there are not many of the logging parameters available for that ECM, I am unsure why but I could only pull about a quarter of what I usually view from the log file you sent.

[Chad541121]

So, I was able to get the vehicle in my possession again. For some reason the MPVI2 will not communicate with the VCM Software. I have tried resyncing and resinstalling the software. Not sure whats going on there.
I did a smoke test on the intake and everything looks great. There was a silent code in the ecm for MAF low circuit. I cleaned it with MAF cleaner and test drove. It didn't make a difference, but the code never returned. Driving it, I can replicate the surge at 36-39% throttle consistantly, no matter what gear its in. It feels like the boost kicks in 2-3 times and then quits. I have read about the vacuum valve going bad but it appears to stay steady when this happens. I am meeting with a guy tomorrow that has the hp tuning equipment also and see if we can get some better information. I do know that it was fine for 20k miles and then the customer took it on a road trip from coast to coast practically and then this surging started. So It shouldn't be a tune issue, even tho it maybe can be corrected with a new tune. I'll chime back when I have more information.

[cadillactech]

Where are you located?

Whipple bypass valves have been known to cause issues but if you think its staying closed when the surge happens then I guess that would rule it out.

Can you monitor misfires while the surge happens? It looks like the throttle and timing are all over the place during the surge when I looked at the data log but there wasn't much else in the way of good data to look at.

[Chad541121]

I?m in northern Indiana. I unplugged the bypass valve and the issue is still present. I also can power brake the vehicle and get the issue to happen and the bypass is steady. Everything the tps is about 35-40% and timing dives is when the surge occurs. All new plugs, wires, and msd coils. New throttle body/tps as well.

[Chad541121]

I am not familiar with the vcm software. I am not seeing a way to view the misfires. Here is a new log file. Clearly can see the timing dropping and that matches the surging exaclty. I can't see any other readings going haywire when this happens. I was able to get the tune file also. If there is something to be looked at there.

Thanks in advance.7-16 118 pm.hpl

[Alvin]

Adding a SCIAP sensor to this type of blower fixes a lot of driveablity issues like surging under cruise, or cruising up hill. It makes the throttle much more predicable too.

I wouldn't tune another PD style blower on a GEN 5 without a SCIAP sensor added at this point.

Search the forum for SCIAP.

[Chad541121]

Update. After spending 2-3 hours trying to figure this out. I have determined that setting the cam from 1 to none the problem disappears. Basically shutting off the vvt. So I turned it back on and tried playing with numbers. The High Baro Thresh was set to 99. Raising it to 118 seems to correct most of it.
The timing calms down and the commanded throttle is steady. So now I need to figure out is this a MAP reading incorrectly? Or do I have a vvt solenoid acting funny or what?
Does this make sense?

[cadillactech]

Update. After spending 2-3 hours trying to figure this out. I have determined that setting the cam from 1 to none the problem disappears. Basically shutting off the vvt. So I turned it back on and tried playing with numbers. The High Baro Thresh was set to 99. Raising it to 118 seems to correct most of it.
The timing calms down and the commanded throttle is steady. So now I need to figure out is this a MAP reading incorrectly? Or do I have a vvt solenoid acting funny or what?
Does this make sense?

MAP sensor readings look ok, setting high baro threshold to 118kpa, sounds like you shut down VVT.

Many issues with VVT solenoids on factory engines, try unplugging it and driving it.

[smokeshow]

SCIAP addition is a definite yes. But this looks to be dominated by the cam phasing. I posted on the truck forum about it a few years ago.

https://www.performancetrucks.net/fo...3/#post5393875

[Chad541121]

SCIAP addition is a definite yes. But this looks to be dominated by the cam phasing. I posted on the truck forum about it a few years ago.

https://www.performancetrucks.net/fo...3/#post5393875

I have just replaced the cam solenoid and sensor. Not the actual phaser though. I will post the low, med, and high for the intake.
I read that thread you posted but I'm not entirely sure what to look for.
Here is a new log file as well. I can see the tps and spark jumping around when I have a steady foot on the pedal.
7-23 118 hi baro 118 new vvt solenoid and valve.hpl
Low Baro.jpg
med baro.png
high baro.png
If I set the high baro value to 94 where the tuner had it then the problem happens more drastically and happens about 38-42% throttle. I posted those logs previously.