Now that full LNF ECU control can be dialed in, explain this prob (cruise control)

[codename Bil Doe]

With the tune dialed, I have found a problem that, so far, cannot be explained. I haven't spent any time looking into this other than I know not to use it. But, with the tune finished for the last couple months, power and cruise mpg killer, racecar flying, I can't use cruise control. The instant I activate cruise control it goes into reduced power mode (no throttle, cruise to a stop unless you turn the car off and on). This issue is consistently repeatable when cruising at 70mph and the cruise is set.

Without having spent any time on it, I'm thinking it could be related to how quickly the car is demanding boost versus the cruise control attempting minor increases to maintain speed and a potential issue with the load increasing with a lack of immediate response because you're in 5th gear. Somewhere in the ECU there is a code being thrown based on a conflict of coding which is not detected or monitored until the cruise control circuit is activated.

I'm guessing that there may be a DTC that can be deactivated or set to no error code to alleviate this issue. It's the only issue that keeps me from saying the tune is 100% done. I'm stuck at 99.94857% . I haven't really cared because I don't use cruise control even on long drives. Anybody else experience this?

[cobaltssoverbooster]

your more like stuck at 90% because of unlisted coding. I've have had multiple groups look into it before and there are things that would be cool to include, but aren't really needed.
i don't use the ecu's anymore so i guess you could say I've stopped researching coding. Cruise Control is very picky and when i made a full race max trq all ranges tune the dals caused cruise control to deactivate. you may have to get into a balancing act with desired and allowable dals.

[MikeM173]

Reduced power comes from actual pedal and electronic pedal being too far split. My guess would be to fix it would be less demand in the area it happens. Obviously other things affect it but it should be capable of getting worked out. I have the same issue but haven't had a chance to play with it.

[T-Man]

Go on CSSOB.... You keep teasing tid bits of cool stuff that "could be". Why not ask the question to HPT team if the coding is there, especially if you know the location.


Bill, I run into this same problem while using cruise control on a relatively long downhill road I drive on. Car gets all wonky and isn't the same until I turn off cruise and reactivate

[codename Bil Doe]

Sorry, I meant 99.94857% of what's available to us, not of the potential of the ECU.

MikeM - I wouldn't want to compromise the tune, itself. I think the pedal vs epedal difference points me in the right direction. I'll scan thru the DTC's and see if I can find one directly related. I think if I can find something to turn off it would only be recommended once a tune has been verified safe for those who are still experimenting.

Difference in pedal vs epedal brings up another scenario in which that doesn't occur - the lambda efficiency table. When I was going through all the tables experimenting, I found some changes in this table which would make the car go instantly WOT on startup. But, it never went to limp mode which the cruise is doing instantly.

I brought my laptop into work today. Let me look around.

[MikeM173]

I forget the tech article I read that stated that but that is why I mentioned it. I feel like because the tunes we have are so aggressive in nature that when cruise is on and it hits a point of a certain rpm range and load that is what causes it to finally go into limp mode with the pedal vs epedal positions. my guess would be work that cruising range some so it is a little less touchy and you should see it fixed. I'm guessing that would be a delicate thing so you don't sacrifice throttle response for WOT scenarios. I only see it around the time I hit 70 if I remember correctly. At that time though my RPMs are a higher then what I am at when I am at lower speeds. I don't usually use cruise at lower speeds though so you may try setting cruise at a lower speed and go up a hill and see if you have the same issue unless you already have verified this or have verified this doesn't happen then.

[cobaltssoverbooster]

ive asked hpt for many things and it comes down to three things:
1) the ecu only has so much internal storage so adding extra coding for special features like live efi tuning will never happen because there just isn't enough room for it.
2) unlocking too much of any particular ecu can result it copyright infringement and major lawsuits. we like hpt software, we don't want them in a lawsuit and loose our tuning capabilities.
3) there is already enough support in this ecu to support over 1000 hp and for everyone else the tune-a-bility of cruise control. adding extra features would just be for the finest of adjustments. adding any features now would cost way more to research and add software coding for than how often the feature will actually be used. as the old saying goes time is money. for the time it will take to code out our un-important wants, they can put that time into code research for many new ecu's including library expansions like we have seen them do recently (ex: addition of opel models and transmission settings on automatic lnf vehicles)


the coding i had done was to source out options for changing a few special requested factory settings. it cost my customer a large amount of money and because it was his bill the information only got shared in ways he had agreed to. i can say our main changes in coding were to change reluctor pattern codes, knock sensor data, BCM reliance delete, and fix a problem i was encountering by re-writing a few codes to bypass heavily relied on sensor inputs.
(hint: some lnf sensors if disconnected or dtc's turned off will not let the engine start. putting in some aftermarket parts cause problems requiring them to be turned off and at the moment there is no way to do it without causing a no-start issue)

i love the lnf ecu for its amount of control for a factory ecu but i replaced them with aftermarket units the last three times i gutted a vehicle for track use. the benefits of the factory ecu are great now but i required additional output circuits that i could control, so naturally out they went.

[|V3nom|]

2) unlocking too much of any particular ecu can result it copyright infringement and major lawsuits. we like hpt software, we don't want them in a lawsuit and loose our tuning capabilities.

does that mean that hpt was given the go-ahead by gm to unlock certain parameters and not others?

[cobaltssoverbooster]

i don't know that answer to be honest. if they were willing to share that info then someone would. im not a rep for any party that would be apart of that issue so i can't say

[lt1z350]

Just had same issue on a 2011 Camaro SS and was in the way I had the throttle set up. Maybe locating the dtc and turning it off will help or just make it not even work. Only option might be a second tune with the throttle tables closer to stock and only use it when really want the cruise to work. I took the Camaro and pushed it until set the code then went back to where it didn't and still was more aggressive than stock but not as linear as I was trying to shoot for but being a guys car at work I was tuning then the cruise is a must and didn't even know the difference of the two ways I had it set so turned out to not be a big deal for him and more for me not being able to push it as far as I liked to.

[codename Bil Doe]

First thing I did was made a list of all possible DTC's. Just haven't had the time to go and test each one. I find no reason to sacrifice performance for cruise control.

[lt1z350]

I guess another possibility is if another table being now off is causing it so to see if anything else needs to be raised to the amount of change as you did to your driver demand if that's what your ECM calls it. The caddy has it that way and so far just raised my outer limits as not to limit power. Like u had said in my thread the ats has tons of crap that is adjustable so haven't looked at a file like yours so didn't know if has a bunch to consider but possibility I guess. Would make for easy fix that's for sure vrs all the codes and going that route.

[codename Bil Doe]

LNF ecu is much simpler in terms of what's available to users. If that was an issue it would be affecting the tune regardless of whether the cruise was on or off. Just need to start messing with DTC's.