E39 LFX Throttle Closing Please Read

[6328]

Recently swapped an 2012 impala lfx engine into our lotus exige cup racecar converted to a manual trans in the pcm. Purchased HP tuners VCM Suite and been having trouble with wot throttle not coming in until 4600 and then closing down at 6400 to about 65%. the throttle pedal is showing 99% but the throttle blade starts closing at 6400. There have been many posts with people with the same problem but no one has posted a resolution. Been working on this for the last three weeks getting ready for the 25 hours of Thunderhill Endurance Race and am running out of time. I have many logs with different configurations that i can post. I am willling to pay for a fix because the race is Dec 3 and the car has to go from Iowa to California the 25th of November. Please help. And by the way i have read the e78 e39 guide at least ten times. Tim. First Log is Mainly stock with 2013 Camaro Manual Trans DD Tables. Second Log raised DD tables to 400 \\\ Third log raised the peak torque 20% Fourth raised the DD tables to 500. Trying to figure out how to upload scan logs.

[6328]

Anybody have any ideas?

[codename Bil Doe]

ust looked up E39 ecu. It's one of the new GM torque-based PID controllers. This style is used on new GM 4/6/8cyl engines and is a derivative of the Bosch LNF. Bad news is it's going to take awhile to understand how to use it. Most people I've seen are tuning them like an LS with no idea what they're doing or any understanding of the difference between DI and port injection. Read this link for a start.

https://www.hptuners.com/help/vcm_ed...vanced_e78.htm

I'll be at the 25, too, as crew and possibly driving.

[codename Bil Doe]

Post your tune

[6328]

This is the last tune file also this is a picture of our car at last years 25 hour race ES Class finished 5th First year. Glad to see a racer reply, It won't let me post the picture?

[6328]

Bump

[codename Bil Doe]

Was at the track all yesterday. I'll dl it now

[6328]

Hers the config File.

[veee8]

I've fought this problem since day one on the 2012+ V6 Camaro's. I believe there is some other table that isn't defined yet. I have been able to open the throttle fully earlier by manipulating the torque coefficients. Basically lowering the reported torque. Should be fine for a manual trans car, but not the what you would want for an automatic.

[6328]

Thanks for the reply, Seems like if someone has figured this out ,and i am sure they have, they are keeping it to themselves. When i do get this figured out and i will i will be sure to let you know because of your response to my post, Tim

[codename Bil Doe]

Veee8 - that's actually the conclusion I came to that 6328 is going to try. I don't believe it's a workaround. It's simply one method of manipulating the calculations to limit the engine.

Brief explanation of how I came to focus on the coefficients is that the only related numbers I've seen so far in logs are the engine torque and torque delivered. They mirror each other. Logically, the engine will not try delivering more torque than it thinks it has.

There is a noticeable dip in the torque coefficients above 5500 rpm. A coefficient is used as follows:

Engine torque = ax+by+cz+...

where a,b,c are constants and x,y,z are variables chosen from the coefficient tables. You don't need to know the algorithm to manipulate it into producing the result you want (higher calculated torque value).

Treat the "x" component as the airflow A map coefficient. Based on cam angle and rpm it chooses that cell and inserts it into the place of "x". Engine torque is calculated and all available engine torque is delivered.

If the calc says 50lbft avail, the engine will do everything to only produce 50lbft (pull timing, close tb) because that's all it thinks it should be delivering. Manipulate the coefficients to produce a calculation of 500lbft and it should do everything possible to get there even if it can't (iow 100% tb open).

An extension of this for predictability would be to make all tables a,b,c,d the same AND make all the cells in one table a single value. Why? Theoretically you would produce a single engine torque calc for all rpm and cam angles.

Suppose that calc is 500lbft for everywhere no matter what. Then, you could use driver demand tables properly to limit your request to a percentage of what's available instead of trying to demand 500%.

I don't have an ecu to play with, but this is the approach I would take.

[jtrosky]

So - stupid question time. Why would the engineers @ GM set the coefficient tables so that the engine isn't using all of it's available potential? Or is it just becuase they didn't spend the time to get the calibration set just right?

Just trying to understand this a little better (I've always been afraid of the coefficient tables!!). :-)

Thank you!

[6328]

I would like to publicly thank codename Bill Doe for all of his help through pms. I can't thank him enough. Tim

[codename Bil Doe]

Thank me when you bring home the trophy. What class are you running?

Jtrosky- warranty. Same reason they detune all their engines. Warranty costs kill profits.

[jtrosky]

So are you saying that doing this will substantically reduce the lifespan of the engine (vs the way it comes stock) - assuming you ran the engine as hard as possible using either configuration?

I'm just trying to learn. I always hear people say that tuning the engine for more performance isn't necessairly bad for the engine. Sounds like that's not 100% true - at least not with this particular "mod"?

[6328]

Bill running ES class.

[veee8]

I have had to use this approach on the new ZO6's to get the throttle to open earlier to once boost has been increased, but only on the Manual cars. hadn't seen the issue on 8 speed auto 2015-16 ZO6's.... but I have had this problem on all 2012+ V6 Camaros. I would not recommend fudging the torque coefficients on an automatic car. The trans won't have the proper torque readings and will likely slip/fail.

[jtrosky]

Well, that is certainly good info to know before attempting this mod! :-) Never a good idea to make a change that will slightly increase the power, but break the trans while doing it! Thanks for your valuable input.

[codename Bil Doe]

Jtrosky- "substantially" is a relative term. Many parts may be designed to handle 600lbft. Many may not. I could take an 89hp honda on a bone stock tune and bounce it off the rev limiter until it pops. LNF's stock dyno 230/230. On E47 they are around 420/420 reliably all day long with just a tune. There are several factors including how you treat the equipment.

[codename Bil Doe]

People need to understand you don't adjust a single table with these ecu's and call it good. You can do it for autos, but you have to understand that changing engine torque calcs will affect other tables. Just saying it'll all explode without undrstanding why is how people don't learn.

If your auto tranny "equation" is Tranny=a*b and you double the a term then you better figure out where to halve the b term to leave tranny settings stock.