Does the PCM "Learn" to pull timing. . .

ricks · Post by **ricks** » Fri Aug 13, 2010 10:05 am

U7135, 09 Challenger SRT, Rev 23b

I just ran my first batch of data logs. I use 93 octane gas.
Regardless of whether I run the 93 tune or the 91 tune, I'm getting the same amounts of LT & ST Knock (lots of retard).

I will try it again with my next tank of different brand gas.
If that doesn't change things, I will add a catch can next (one step at a time. . .).

My question is: Does the PCM "Learn" to pull timing, and do it from memory; or does it only pull timing if it sees detonation (on a case-by-case basis)?

Does it learn that, "Hey, 100% throttle has given me knock every time out of the last 500 times, so I'm going to pull timing automatically just to be ahead of the game." Or, does it only pull timing when it senses knock?

If it does pull it from memory: Should I R&R the PCM fuse after changing tunes (or switching brands of gas) before I data log again?

Thanks,
Rick

gdragich · Post by **gdragich** » Fri Aug 13, 2010 8:41 pm

Yes it does in a sense, that's what the LT KNK is. The ECM has learned that at those points where you see LT that it needs to proactively pull timing. If you are also seeing ST KNK there then you should add the 2 to get the actual timing being pulled. You would need to pull fuse 11 to clear these adaptives or the negative battery cable for at least 30 seconds.

HerDaytona · Post by **HerDaytona** » Sat Aug 14, 2010 1:08 am

Let me say first off that you are at least taking the time to learn the logging routine. Don't go and pull timing, start by adding fuel. Make sure you have the best fuel in your gas tank. Adding fuel maybe in the neighborhood of 5-7% where you see the LT knock retard. Then log again. See ST and LT knock add more.

One thing that is important with OUR Hemis is the Intake Temps. Do what you can to isolate you CAI from underhood heat. That will help also in the knock department.

Big Start for you and good luck.
Add the catch can No Matter What.
Enjoy

Everytime you load a tune adaptives are reset for the PCM.

brandy16 · Post by **brandy16** » Sat Aug 14, 2010 2:22 pm

There are no pcm adaptive s. They are TCM adaptive s and they do not get reset with the install of the tune. You have to go to modify tune to reset the TCM adaptive s

bigsnake · Post by **bigsnake** » Sun Aug 15, 2010 3:09 pm

brandy16 wrote:There are no pcm adaptive s. They are TCM adaptive s and they do not get reset with the install of the tune. You have to go to modify tune to reset the TCM adaptive s

I disagree, there are PCM adaptives and they can be cleared !!!

Clearing PCM Adaptive Programming Memory

Open the cover on the IPM (Integrated Power Module or Engine fuse
block/power center) and pull Fuse F2 for a count of approximately
15 seconds resets the adaptives .

Note: (according to a Chrysler tech with 25 years experience, only 15 seconds is needed to clear)
Here's what it does! Pulling Fuse 2 resets;

- All PCM DTCs erased.
- All OBD2 monitor results erased.
- All long term fuel trim adaptive values reset to Zero.

Make sure your car is turned off and the key is in your pocket while doing the pull.!

It is a 25 amp beige fuse !

ricks · Post by **ricks** » Sun Aug 15, 2010 3:54 pm

Thanks Everyone.

Bigsnake: That's what I was thinking.

Are we sure that changing the tune resets the PCM?

brandy16 · Post by **brandy16** » Sun Aug 15, 2010 5:57 pm

I found a link that may help. I did not see anything about re setting the timing.I hope I got this link on here http://www.jeepsunlimited.com/forums/sh ... ?p=3291665 Sorry for any misunderstanding.

bigsnake · Post by **bigsnake** » Mon Aug 16, 2010 8:19 am

ricks wrote:Thanks Everyone.

Bigsnake: That's what I was thinking.

Are we sure that changing the tune resets the PCM?

I'm sure one of the guy's at Diablo can explain this better but it's my understanding that the "tunes" are written in a protected area of the PCM and pulling fuse 2 is a different procedure. So I don't believe changing a tune resets the PCM.

Post by **mikel** » Mon Aug 16, 2010 12:24 pm

Flashing will generally always reset adaptives, yes....

FAhemiST · Post by **FAhemiST** » Mon Aug 16, 2010 1:01 pm

and depending on who is flashing, it may make your pants tighter

Post by **mikel** » Mon Aug 16, 2010 1:13 pm

indeed....lol.

bigsnake · Post by **bigsnake** » Mon Aug 16, 2010 5:30 pm

mikel wrote:Flashing will generally always reset adaptives, yes....

Want to be sure I understand this, to me flashing would be going to the dealer and them flashing a new crom in which I understand would reset adaptives. Are you saying if I go from a 93 tune then back to original tune then to a 93 CAI tune it will reset the PCM adaptives ?

FAhemiST · Post by **FAhemiST** » Mon Aug 16, 2010 6:29 pm

bigsnake wrote: Are you saying if I go from a 93 tune then back to original tune then to a 93 CAI tune it will reset the PCM adaptives ?

yes, any time you change tunes

DGatzby1 · Post by **DGatzby1** » Mon Aug 16, 2010 10:27 pm

bigsnake, every once in a while if I have not reflashed a tune, especially after driving around like a granny I reset the adaptives off the Predator menu. It seems to make a difference. I know it makes a difference after some winter driving up here. After a reset it is more responsive I think.

duster360 · Post by **duster360** » Tue Aug 17, 2010 9:09 am

There are many different adaptive learning routines in the PCM

1) Closed loop Fuel trims for the left and right side of the engine---they are independant from on another
2) Knock retard, which was already mentioned
3) Throttle/Pedal--DGatzby1 this is what you're talking about
4) Tip-in spark retard
5) VVT for 09 newer 5.7
6) trans has its own learning strategy for shift points and firmness.
7) SRT-4's have Wastegate adaptive learning for boost control

I think thats about it.

On the majority of PCMs, flashing a tune will clear the Long term adaptives.