OSS is VSSOriginally Posted by Enginerd_Rob
The 3000RPM thing is changed by adjusting trans/stall speed. This needs to be done even if foot braking that high. Yes I know there are some who want to sell you a transbrake and will tell you that theirs needs no calibration changes whatsoever, believe that at your own risk.
Thanks for the info.
Are you talking about inferred movement also, or just stall speed?
Is there a rule of thumb for values to enter on stall speed vs converter model (3C, 4C, 5C)? In my case I'm running a 5C.
Last edited by Enginerd_Rob; 08-10-2016 at 10:03 AM.
In this case I'm just talking about stall speed. Just raise it up way out of the way to a point where you won't reach that RPM on the brake.
My inferred and stall speed are currently at 8000.
Damn, I thought this was going to be it!
I have both inferred and stall speed at 8000 too and I still ran into the RPM limit. So unfortunately that's not it.
Also I'll add that I don't think having a transbrake matters Enginerd_Rob. I get it while just on a 2 step. And as I've mentioned, I also get it on burnouts.
And to be clear, your not using the 2 step during burnouts right?
Watching your log is interesting. It starts with the commanded gear as "unknown: 01" and stays like that until you hit 4000 rpms, at which time it reads "1st". From there we see it go to "unknown: 03, then "2nd", then as rpms drop near 4000 it goes to "unknown: 05". When it drops below 4000, it triggers the torque source 4 limit. It seems like 4000 rpm has significance.
Looking at my SCT log, my torque source 4 was also triggered immediately after hitting 4000 rpm. My SCT log shows commanded gears as being normal (ie. no "unknown").
We need to figure this out!
On this log, we also see torque source 4 triggered right at the 4000 rpm mark.
Yes exactly. I'm not on the 2-step during burnouts. I'm pretty confident that what I'm seeing on my burnouts is essentially the same RPM limit we sometimes see at launch. It has to be something related to a combo of vehicle speed (or the speed the ECU thinks I'm going during my burnout), RPM and gear that is triggering this RPM limit.
I believe eric said he fixed that. has anyone tried logging with the latest version?
Yes I did on 8-6 with the latest. I was still seeing the "unknown" for commanded gears. Unfortunately I can't datalog this weekend because my car is getting long tube headers put on and I'm not going to have it back until next week. Waiting for an X-Pipe. But I'll post up my logs tomorrow from the 6th for everybody to see along with with what params were set for each pass.
I'm racing this weekend. I've never tried to log with the HP software (only the SCT X4), but I'll see if I can get it working.
Last edited by Enginerd_Rob; 08-12-2016 at 09:05 AM.
I'll be looking forward to the log. Can you attach the tune here please. I want to take a look.
Eric Brooks
HP Tuners, LLC
Thanks so much for your help on this Eric!
Attached 2 logs. Now I've been experiencing this problem for quite some time. So I've attached 3 logs and 3 tunes. One from a burnout on 7-3-15 and the tune from that day. And two logs from 8-6-16 and the tunes from that day. The reason I wanted to show a log and tune from 7-3-15 is because I've made a lot of changes to the tune. So the one from 7-3 is much closer to a stock tune and I was still experiencing the issue even then.
On the 7-3-15 log which is during a burnout, I wasn't logging torque source, but if you look at time 7:31:53:606, you see the torque request fall off to virtually nothing at about 3300 RPM's and then the torque jumps back up after the RPM's drop quite a bit. I'm confident that's the same RPM limit issue even though I don't have torque source logged.
On the 8-6-16 log 1, I have both my burnout and launch logged and I experienced the RPM limit during the launch but not during the burnout. What I was experimenting with was low/reverse max VSS. On this log I have it set to 5MPH. At time 5:58:35:722 you'll see the RPM limit.
On 8-6-16 log 2, I only have the burnout in the log. I didn't experience it on the launch during this pass. At time 6:44:50:178 you'll see the RPM limit. low/reverse max VSS was set to 10MPH on this run.
I could only attach 5 files. Here is the 7-3 log
I just went out on the street and tested a burnout and launch, logging with the VCM scanner.
In the log, I did a burnout starting in manual 1, shifted to manual 2, then manual 3. At the beginning of the burnout I had the torque source 4 popup at the 7:33:14.95 mark.
After the burnout I rolled forward, stopped, put in drive, then got on the transbrake (3200 rpm 2-step limit) and launched. I let off right after launch.
Attached is the log and tune:
Yes, your RPM limit while doing your burnout is the exact same thing I'm seeing. It's something about first gear, the RPM around 3300 RPM's and the MPH that is triggering it. It's easier to recreate in a burnout, but it's without a doubt the same thing we sometimes see at launch too. Hopefully Eric can figure out what it is. This limit really holds back the potential for this car to be a consistent car at the track.
At the track now... Here's a clean pass (no TQ source 4). Log is a 3rd gear only burnout then a full 1/4 mile pass.
After a lot of time studying this, I have a theory...
It looks like the Torque Source 4 is triggered by the Trans Calculated Gear Ratio exceeding 5.00.
As best I can tell, the ratio is calculated as Trans Input Shaft RPM divided by Trans Output Shaft RPM.
When the car is not moving, this ratio defaults to 5.00 regardless of the Engine RPM, TCC Slip, or Input Shaft RPM.
As the car begins to move (rear wheel speed starts to register) or a burnout starts (again rear wheel speed starts to register), the trans starts to calculate this ratio.
The first few data points as the wheel speed starts to register don't match the calculated ratio, which I think is due to the resolution of the logger. Eventually though the numbers match.
On a good burnout and launch, I am not seeing the ratio exceed 5.00. I'm thinking that 5.00 is the max allowed calculated ratio, and if it's exceeded, it tells the throttle to close to slow down the input shaft.
Eric@HPTuners, is there a variable somewhere that affects Max Trans Calculated Gear Ratio?
Thanks,
Rob
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