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reading through an AEM wideband pass through? anything else installed on the car that might interfere? I haven't seen this yet, but I will log for it next time I am in the Z. Do you have any other PIDs vs this list or it's the same? Also what OS/cal are you two using, maybe it's the same? Mine is 12678648 and fuel system is 12680360.
Last edited by Higgs Boson; Dec 23, 2019 at 11:31 PM.
reading through an AEM wideband pass through? anything else installed on the car that might interfere? I haven't seen this yet, but I will log for it next time I am in the Z. Do you have any other PIDs vs this list or it's the same? Also what OS/cal are you two using, maybe it's the same? Mine is 12678648 and fuel system is 12680360.
I've experienced it on my car with and without the AEM passthrough, and a couple of other customer cars the same. I experienced this before I installed the dsx aux kit, so I don't think it's the issue and the only other aftermarket electronic device in my car is the flex fuel kit other than a mirror tap for a radar detector that seldomly have plugged in.
I only ever see this on vettes though, none of the camaros I tune have the issue. The truly odd part to me is how sometimes it will just work and then flatline within the same log and come back again.
I still need to get a hold of another mpvi1 to test with, that will be my next step after the holidays. From the times it does work though, I do know my aux fuel kit is working at least cause I can see the low pressure ramp in.
My ECU OS is 12665218 and Fuel system is 12653904. I just updated them with sps a couple of months ago, but I was thinking about seeing if there was another cal out there.
This is what I was logging to try and make sure the tables I was in for the DSX kit.
I wonder if it's the different OS doing it, no signs of it on my logs. In fact my lift pump pressure varies quite a bit, bouncing around commanded, 54-64 give or take during normal driving and idle, looks like O2 sensors switching.
I have the AEM wideband on my car and the DSX low side as well. I physically unplugged both and the flatline issue was still occurring so safe to say not the issue. Specifically happening on "Fuel Pressure (SAE)" PID which is the low side PSI reading. It will do it regardless if that's the only PID monitored or if I have a ton of others logging. Mine too looks like an o2 sensor when its working, but then will randomly just flatline at 57.9psi
In short review of my diag, I also installed a new low side sensor, ohm checked, short checked, voltage drop tested all the low side wiring from sensor to ECU, verified 5v reference. Checked ECU powers and grounds. Installed and programmed new ECU with factory GM equipment and tune, Replaced fuel pump driver. None of it ever corrected the issue. I also verified with a physical gauge that the car is still hitting its commanded lift PSI, even though the sensor reading is flatlined. Its either a software error within GMs operating system(s) , or its a hardware error of what we are using to communicate (ie the MPIV2). @Higgs Boson ... What HPTuners device are you using?
Ill have to check the operating system and report back, but with that said, I also saw this issue on a 14 stingray (Mine being a 15 Z06)
Does it take a certain amount of time in the log for this to start occurring? Generally my logs are not very long before I restart them. I try to get specific data, save the log, get other specific data, save, and so on.
Does it take a certain amount of time in the log for this to start occurring? Generally my logs are not very long before I restart them. I try to get specific data, save the log, get other specific data, save, and so on.
For me it's pretty random. Usually my logs are 5-10 mins long. When I get home from Christmas travels I can upload an example
@sevinn You give up on this one yet? New firmware on my MVIP2 , ran all the updates on on VCM scanner. Still happening. I requested months ago from HP to add the low side voltage PID so I can just write the math to convert to PSI, still not there. . Just sent support another email
@sevinn You give up on this one yet? New firmware on my MVIP2 , ran all the updates on on VCM scanner. Still happening. I requested months ago from HP to add the low side voltage PID so I can just write the math to convert to PSI, still not there.
@atljar Yeah I've been dealing with it because nothing we've tried has worked. My next move on my car at least is that I'm installing a nitrous outlet kit with the promax controller so I'm going to tap into the low side feed signal wire at the ecu and basically bypass hpt on it. I did buy a new vcx nano device, so I'm going to go out and make sure if I log fuel pressure with gds2 everything looks good to kind of confirm that it's an hpt issue.
I do find that it happens to work a little more often now, or at least I get a jagged line instead of a flat one so I can kind of infer my pressures based on the peaks.
@atljar Yeah I've been dealing with it because nothing we've tried has worked. My next move on my car at least is that I'm installing a nitrous outlet kit with the promax controller so I'm going to tap into the low side feed signal wire at the ecu and basically bypass hpt on it. I did buy a new vcx nano device, so I'm going to go out and make sure if I log fuel pressure with gds2 everything looks good to kind of confirm that it's an hpt issue.
I do find that it happens to work a little more often now, or at least I get a jagged line instead of a flat one so I can kind of infer my pressures based on the peaks.
My VCX Nano with GDS2 also malfunctions. Just as a FYI. I wasnt ever able to get my hands on a genuine MDI2 to test or a MPVI1. My thought is it may be an issue in the USB drivers on the HP/Nano? Who knows.
Regardless, there is a voltage PID for the low side sensor in GDS2 which always reads correctly. I keep trying to get HP to add it to VCM scanner, but no dice. Happy 4th!
Did anyone find a fix for this or another way of verifying the low side pressure correctly? Short of putting a sensor in where the feed line connects to the under manifold feed line I was hoping someone here may have found a solution.
The exact same thing is going on with my car and I actually think it's gotten worse just over a couple weeks. I initially thought the low side was dropping pressure but I now think it's the pid going in and out leaving spikes of commanded pressure all the way down to 57.9 psi which for some reason is what the pid will flatline at. High side looks good no issues there. I'm using hptuners vcm scanner and an mpvi2. Reading the replies about hptuners not doing anything about it makes me not want to even put a ticket in. I plan to throw some more boost and fuel at it so I wanted to get some baseline numbers and while doing the logging noticed this odd phenomena.
I've seen the Fuel Pressure SAE (low side) PID work properly on most C7's and Gen 6 Camaro's but I have noticed that the newer cars(2019+) sometimes have inconsistent low side readings from the PID. Make sure your sample rate for this PID is set to fastest. I haven't been able to determine why some cars are fine and some are not. But I've seen it enough times now to know, as long as high side is holding steady, the low side PID is likely wrong.
I've seen the Fuel Pressure SAE (low side) PID work properly on most C7's and Gen 6 Camaro's but I have noticed that the newer cars(2019+) sometimes have inconsistent low side readings from the PID. Make sure your sample rate for this PID is set to fastest. I haven't been able to determine why some cars are fine and some are not. But I've seen it enough times now to know, as long as high side is holding steady, the low side PID is likely wrong.
Yes I've tried many different things but nothings been a 100% fix. I've tried flashing to the completely stock tune. Reading only the low side pid with vcm scanner. Turning the poll rate to fastest. Reconnecting to the vehicle multiple times. Throttle modulation. Nothing works. Sometimes the signal comes back and sometimes it doesn't. It almost never is fully present during a pull though.
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. Just sent support another email
