Cold Start Auto Rev

[MechEngineer17]

Not sure if the RaceME Ultra is the same, but with the MM3, you choose the PIDs and record a data log.

Import the captured data into Excel and plot a graph.

If you have a higher-end scan tool, you can simply pick the PID, and it will plot a graph.

See attached examples.

Thank you, that's a lot of help!

The RaceME Ultra does provide data logging.

I just have not had a reason to use it yet.

I'll do some digging tonight and see what I can make of it; hopefully, I'll get something going.


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[kgharrin]

Thank you, that's a lot of help!

The RaceME Ultra does provide data logging.

I just have not had a reason to use it yet.

I'll do some digging tonight and see what I can make of it; hopefully, I'll get something going.


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Worst case if you can't data log, just get those 4 parameters on one display (desired & actual fuel pressure + desired & actual VGT) and watch them closely while it stumbles.

Keep an eye on the difference between desired and actual rail pressure and VGT position.

A small deviation is fine, but if you are significantly off in steady state, let us know.

Off the hip, I wouldn't bat an eye at a couple percent error in VGT in the transient regions (while the desired position is changing) and for the fuel pressure.

I'm guessing a couple hundred PSI is nothing to worry about (especially in transients if that's wrong, someone will correct me) but if it is more than that (certainly more than 1000 psi error) let us know.

Of course, a data log onto your SD card will make it easier, but not required.

Good luck!

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[MechEngineer17]

Worst case if you can't data log, just get those 4 parameters on one display (desired & actual fuel pressure + desired & actual VGT) and watch them closely while it stumbles.

Keep an eye on the difference between desired and actual rail pressure and VGT position.

A small deviation is fine, but if you are significantly off in steady state, let us know.

Off the hip, I wouldn't bat an eye at a couple percent error in VGT in the transient regions (while the desired position is changing) and for the fuel pressure.

I'm guessing a couple hundred PSI is nothing to worry about (especially in transients if that's wrong, someone will correct me) but if it is more than that (certainly more than 1000 psi error) let us know.

Of course, a data log onto your SD card will make it easier, but not required.

Good luck!

That’s perfect.

I appreciate the detailed response!

On my way home, I already found those options and configured a screen just for that, so come morning, I will log it.

I just have to figure out how to export to excel using the raceme, but I’ll dig some more I just haven’t gotten that far yet.


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[MechEngineer17]

Worst case if you can't data log, just get those 4 parameters on one display (desired & actual fuel pressure + desired & actual VGT) and watch them closely while it stumbles.

Keep an eye on the difference between desired and actual rail pressure and VGT position.

A small deviation is fine, but if you are significantly off in steady state, let us know.

Off the hip, I wouldn't bat an eye at a couple percent error in VGT in the transient regions (while the desired position is changing) and for the fuel pressure.

I'm guessing a couple hundred PSI is nothing to worry about (especially in transients if that's wrong, someone will correct me) but if it is more than that (certainly more than 1000 psi error) let us know.

Of course, a data log onto your SD card will make it easier, but not required.

Good luck!

Alright, I have another update for everyone. I am attaching two photos of two separate graphs that I have condensed down to the area in which the truck is stumbling. The before is totally normal, the idle, fuel, and VGT numbers are consistent so I shortened the graph as to show a small bit of idle before the stumble. Based off of what I was experiencing it is only when the truck tries to enter high idle. With the exhaust brake on the truck is fine but when it trys to enter high idle with the exhaust brake in the truck idles up then drops rpm and fuel respectively, as seen in the graphs. Respectively as rpm increases so does fuel while the VGT opens (or decreases on the chart). There are a few spots that concern me in the fuel pressure that may be concerning where the desired spikes but the actual is low, then catches up. I am not sure as to why the truck will not stay at high idle with the exhaust brake on. Let me know what you think of these graphs to see if there’s something that stands out that I don’t see.




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[AK Bob]

Alright, I have another update for everyone. I am attaching two photos of two separate graphs that I have condensed down to the area in which the truck is stumbling. The before is totally normal, the idle, fuel, and VGT numbers are consistent so I shortened the graph as to show a small bit of idle before the stumble. Based off of what I was experiencing it is only when the truck tries to enter high idle. With the exhaust brake on the truck is fine but when it trys to enter high idle with the exhaust brake in the truck idles up then drops rpm and fuel respectively, as seen in the graphs. Respectively as rpm increases so does fuel while the VGT opens (or decreases on the chart). There are a few spots that concern me in the fuel pressure that may be concerning where the desired spikes but the actual is low, then catches up. I am not sure as to why the truck will not stay at high idle with the exhaust brake on. Let me know what you think of these graphs to see if there’s something that stands out that I don’t see.https://uploads.tapatalk-cdn.com/202...8eb670e4b8.jpg

https://uploads.tapatalk-cdn.com/202...8a932cd0cd.jpg


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Nice job on the graphs. I tend to agree with @kgharrin, your fuel control actuator may be sticking. The actual rail pressure is sometimes as much as 1,750 psi lower than desired then slowly tries to recover. The turbo actuator actual and desired look great.

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[kgharrin]

Alright, I have another update for everyone. I am attaching two photos of two separate graphs that I have condensed down to the area in which the truck is stumbling. The before is totally normal, the idle, fuel, and VGT numbers are consistent so I shortened the graph as to show a small bit of idle before the stumble. Based off of what I was experiencing it is only when the truck tries to enter high idle. With the exhaust brake on the truck is fine but when it trys to enter high idle with the exhaust brake in the truck idles up then drops rpm and fuel respectively, as seen in the graphs. Respectively as rpm increases so does fuel while the VGT opens (or decreases on the chart). There are a few spots that concern me in the fuel pressure that may be concerning where the desired spikes but the actual is low, then catches up. I am not sure as to why the truck will not stay at high idle with the exhaust brake on. Let me know what you think of these graphs to see if there’s something that stands out that I don’t see.

So The points that I would be skeptical of are the ones I circled below. You successfully enter high idle (~1100 rpm) and then as the exhaust brake starts to close and your VGT reaches about 95%, you see the desired rail pressure rise and the actual is stagnant or decreasing. It is very consistent at 95% VGT that this happens. I also think the error in fuel pressure at the beginning (time = 60 seconds) leaves something to be desired as well even though it wasn't stumbling at that point.

Hopefully I am not steering you wrong here, but I think the FCA could be sticking (Your VGT positions look great) I know one way to test this is to unplug it and fuel rail pressure should max out, but i've never been comfortable enough to do this myself. Maybe someone else cam chime in on further diagnostics.

If this is in fact the issue, it is a very easy replacement (knock on wood).

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[kgharrin]

I guess the initial region where I mentioned it being less than ideal is after the high idle was activated too, but your fueling was so low that it couldn't increase engine speed. So when it aborted the exhaust brake (~92 seconds), the load on the engine was reduced and it was then able to go to the full high idle speed, but then once the engine saw some load ramped in from the brake, it started that vicious cycle which I circled.

So technically I should have circled the two prior events as well, but the point holds true.

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[MechEngineer17]

Nice job on the graphs. I tend to agree with @kgharrin, your fuel control actuator may be sticking. The actual rail pressure is sometimes as much as 1,750 psi lower than desired then slowly tries to recover. The turbo actuator actual and desired look great.

Thank you I appreciate it! I noticed the same thing you did and it was concerning to me but I wasn’t sure it that was something that was normal and I just don’t know enough but I had a gut feeling it was not normal. As far as the VGT I agree it looks good and it performs just as well!


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[AK Bob]

Thank you I appreciate it! I noticed the same thing you did and it was concerning to me but I wasn’t sure it that was something that was normal and I just don’t know enough but I had a gut feeling it was not normal. As far as the VGT I agree it looks good and it performs just as well!


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Hopefully others will also chime in and have suggestions. My next step would be to install a new Bosch FCA, but they are quite expensive. Maybe it would be worth trying a cheap knockoff from Amazon first, just as a test to see if the problem goes away.

https://www.amazon.com/AKWH-Pressure...Q%3D%3D&sr=8-3

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[MechEngineer17]

I guess the initial region where I mentioned it being less than ideal is after the high idle was activated too, but your fueling was so low that it couldn't increase engine speed. So when it aborted the exhaust brake (~92 seconds), the load on the engine was reduced and it was then able to go to the full high idle speed, but then once the engine saw some load ramped in from the brake, it started that vicious cycle which I circled.

So technically I should have circled the two prior events as well, but the point holds true.

I see exactly what you mean! The more you explained how it was working the more it made perfect sense. You put what I was trying to say into better wording. It would make sense as to the FCA sticking during idle up. I am almost tempted to swap the part out just to be sure. Because honestly idk how confident I would be with unplugging it and leaving the pump unmetered at full tilt. If I leave the truck plugged in for an hour or two in the morning would that be enough to warm up the FCA as well to avoid the issue? I’m curious as to how that would work just for the heck of it.


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