gen 4 engine dyno tuning (no trans) fault codes and limp mode

[EFIExpress]

Hey guys,

I haven't done many gen4 PCMs yet, first one bolted to my engine dyno this week and I'm having trouble disabling some of the DTCs so that it doesn't throttle limit on me with the trans being absent.

So, this is a 5.3 express van engine, 2008. attached is a log file and the current tune. I've tried disabling some of the fault code tests and setting temperature thresholds to implausible levels but it continues to cut throttle (limits to around 50% in the logs) and then redline is 500 rpm before my programmed values in the ECM. I also tried telling the trans controller the type was "manual" as well, same issues.

in gen3 all of the trans codes can be disabled individually by p code, in gen4 it looks like most of them in the p09xx range cant be altered?


any ideas where to look to make changes so this will dyno properly and I can finish my tuning?

Thanks

gen4_throttle_limiting_no_trans.hplgen4 stage 1 5 3 work file.hpt

[Russ K]

You need to use the 2.25, as it has a separate trans DTC tab.

Russ Kemp

[schpenxel]

Is PE disabled on purpose except at WOT?

[EFIExpress]

I've emailed HPT for a link to the beta. I'll give that a shot.

Schpenxel: this file is mostly stock aside from some idle changes and DTC stuff. its probably not hitting PE due to limp mode would be my guess.

[schpenxel]

PE is set to not come in until the throttle is over 87% regardless of RPM, etc. Then with limp mode limiting throttle it won't ever get that high from what I was able to see

Anyways.. not really part of your original issue, just curious.

[EFIExpress]

Ok,

I downloaded the 2.25 beta. as advertised it exposed some DTCs I needed to kill, namely shift solenoids and things of that nature.

with all of that (sess disabled, no error reported) killed I now have no DTCs at the end of a pull, yet its still throttle limiting on me.

here are the current log and config:

gen4 throttle limiting trans dtc disabled.hptgen4 still throttle limiting no dtc.hpl


what am I missing?

[EFIExpress]

ok. closer.

not sure exactly what fixed the throttle limiting but I:

set number of active cams to 0 (its got an aftermarket cam)
maxed out the various torque limits in torque management

so thats all good, or close to it. it hits 85% throttle, not sure if thats still partially limited or normal for this vehicle but manifold pressure is close to 100kpa so probably ok. its throttle cutting me at 6k despite limit being set at 6750. strange thing is that I got one pull all the way to 6500 but was unable to duplicate it. no DTCs.

I'll keep digging.


pe allowed 6k cut.hplgen 4 PE allowed 6k cut.hpt

[schpenxel]

88% is the normal "max" so you are close

Throttle relearn maybe to get the last 3%?

You can also log pedal position, voltage, etc. to make sure it's registering that the pedal is all the way down

[Russ K]

You need to log ETC%, not TPS%. Also if you log the commanded AFR, then the AFR Error% histogram will work.

Russ Kemp

[EFIExpress]

yeah. ETC% is 100%, so I'm good there.

still cutting at 6k. I'll keep digging.

[schpenxel]

Agree... need to be logging commanded AFR or commanded EQ ratio

The only thing I can find that references 6000 RPM's is under fuel-->cutoff, startup modifiers, cold engine. I wouldn't think this would matter after it's running a while but can't hurt to try adjusting it anyways. I'd just max out the whole table and see if that fixes it. If so, then you can come back and change it to something more reasonable for the colder temps, etc.

[EFIExpress]

thanks. that was it. coolant redline modifier. missed it as I was going over the cutoff/dfco stuff.

Thanks Schpenxel!

[waynehartwig]

What about default trans limit under torque management?