Smoke_ur_5.0

iTrader: (2)

John, I couldn't tell you exactly the logic behind it but I don't think it has anything to do with the tuning to make it do that. Even a stock car will dyno lets say 300rwhp it's first pull but on the third will make it's best numbers and stay consistant from there on after. It could also be that the load is different on the dyno compared to the street..so no matter how much you floor it on the street through the gears it will still stay the same way once you get to the dyno of the first pull being low.

Don't know if that makes any sense but it's something I have seen every car no matter what the tune do on the dyno.

John B

iTrader: (10)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Even a stock car will dyno lets say 300rwhp it's first pull but on the third will make it's best numbers and stay consistant from there on after. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Mark, I think that you mis-read my post....I said after I have made at least three runs.....in some cases four or five runs and then re-flashed the PCM I made ~10 more RWHP.

H82BBad

I have noticed the same thing,make more power when reflashing the same program.Doesnt make sense does it.

Smoke_ur_5.0

iTrader: (2)

I see what your saying now. That is quite interesting. I've never had that problem though.

John B

iTrader: (10)

I have run my car on the dyno 49 times already. What's very odd to me is that whenever I base line the car by making 3 runs to clean out the carbon and stabilize the power numbers I can always expect to be about 10-15 RWHP less than the last time on the dyno. Since I ATAP every time I dyno I can always see that the operating conditions are the same (timing, O2's, NR, etc)

On three separate occassions I observed this and tried reflashing my PCM with the exact same program that the PCM is currently programmed with at the time and immediately found at least 10 RWHP bringing me back to the last set of numbers that I had. What's even stranger is that I have both my octane tables set to the same timing numbers so I know that I can't use the excuse that I had bad gas and the PCM was using the low octane table.

Anyone else experience this or have any thoughts as to exactly what is going on here?

NoGo

iTrader: (2)

You can get the same result by forcing the car to open loop (locking LTerms).

I don't know why it does it either. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

I think it has to something to do with locked fuel corrections. When you reflash the PCM, it has to finish its Emmissions calibrations and tests before it gets to internal calibration....

If somebody knows exactly what tables the PCM kicks over too once the emmissions calibration is finished it would be very helpful.

my .02

John B

iTrader: (10)

I will write to Ken Kelly and see if he knows. What's interesting to validate this theory after the fact was that in hindsight I reflashed my PCM the last time I was at the track to raise the rev limited and noticed that I picked up 1 MPH and thought then that the increase in MPH was just due to better traction on that run abd the ones after this. I believe now it had to do with reflashing the same program because all I changed was the rev limiter and the car did run a hair faster.

Team ZR-1

John you did not mention what the parameters look like and how they change over time after flashing.

Flash would cause a reset thus flushing out any learning PCM has done and if the tune is not "right on" then overtime with PCM adapting the performance drops.
The longer your on dyno/higher load, exp if over 10 mimutes engine run time PCM has readjsted to the higher engine load and what the tuning parameters that were used.
As a simple example if the engine ran at idle for over 10 minutes the PCM would adjust LTFTs which are also used in part throttle but now is biased towards how the AFR was during idle.

Instead of flashing try a test where you pull the 2 PCM fuses and then doing your tests and see what the results look like.

With my Ease scanner I do it different, I send a command to PCM and it resets all fuel trims to zero thus engine is not running from past learning/adapting.
Call me if you want to discuss in detail.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by John B:
<strong> I will write to Ken Kelly and see if he knows. What's interesting to validate this theory after the fact was that in hindsight I reflashed my PCM the last time I was at the track to raise the rev limited and noticed that I picked up 1 MPH and thought then that the increase in MPH was just due to better traction on that run abd the ones after this. I believe now it had to do with reflashing the same program because all I changed was the rev limiter and the car did run a hair faster. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

John B

iTrader: (10)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> John you did not mention what the parameters look like and how they change over time after flashing </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Everything looks good....typically no NR, timing in the 27° range (where I set it) with O2's in the 0.890 to 0.930 range with the LTFT's always showing "0" at WOT before and after reflash. This is why it doesn't make sense to me because the numbers really look about the same before and after.

Team ZR-1

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by John B:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> John you did not mention what the parameters look like and how they change over time after flashing </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Everything looks good....typically no NR, timing in the 27° range (where I set it) with O2's in the 0.890 to 0.930 range with the LTFT's always showing "0" at WOT before and after reflash. This is why it doesn't make sense to me because the numbers really look about the same before and after. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What fuel trim cells are you using to determine those values and what is the value of STFTs since engine runs off of them and not LTFT ?

John B

iTrader: (10)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> What fuel trim cells are you using to determine those values and what is the value of STFTs since engine runs off of them and not LTFT </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Cell 22. I am only recording LTFT's on the dyno and track runs at WOT not the STFT's. Should I be looking at them too at WOT?

Team ZR-1

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by John B:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> What fuel trim cells are you using to determine those values and what is the value of STFTs since engine runs off of them and not LTFT </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Cell 22. I am only recording LTFT's on the dyno and track runs at WOT not the STFT's. Should I be looking at them too at WOT? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Your not getting a clear snapshot looking at only cell 22 and LTFTs.

Engine does not function off of LTFTs, its used to make LONG TERM changes, PCM functions out of the program in the PCM's ROM, the strategies and the calibration tables.
LTFTs are not even acted on by PCM in several minute intervals so why look at them for seeing realtime conditions ?

Cell 22 does not sit in the higher engine load of the cell blocks.
You should look at cells, 3, 7, 11, 15 and 22
for load conditions.

The early PCMs had 16 cell blocks ( 0 to 15) thus 15 was WOT, EPA made changes wanting to watchdog more idle and AC conditions (16-22), thus more cells were appended to the end of the existing blocks, which covers across the MAF freq, RPM and engine load. Cell 15 being higher in the block structure can handle higher loads then cell 22 since it is lower in hte cells block matrix.

By logging STFTs you can see more of the realtime conditions from PE to WOT and thus any changes over the dyno time since PCM functions not from sensors in real time but off the stratagies in ROM and only every 10 minutes does PCM do some adaptive learning.

If your record engine load and fuel learn PIDs you will get a better idea of when the engine is really in PE or WOT.
You also see on a dyno that you may only have few engine cycles when engine is in true WOT, which is 100% engine load and thus you've really been tuning more for PE then for WOT with the PIDs you are scanning.

Lastly the scanner is most important, if it cannot see around 10 engine cycles per second then your missing good data since your not doing a dyno run but for a minute or 2, thus PCM is running on ROM strategies not what sensors or trims have reported. Even 02s are only be acted on once a second.

This is explained in Charles Probst's book I have been mentioning for last couple of years.

RUF SS

I have my car PCM done by MTI. I did dyno about 6 times on 2 different dynos with months in between dynos, and all with the same #s (448 to 451 rwhp).

I try to see what MTI did change on the PCM. And I noticed that they did not tune the car from the PE table!! I am confused, everyone says tune the PCM from the PE table but mine is not. It is still making good power, but what was exactly changed, I think it is the high/low Octane vs. RPM and TQ management. Other than that, I do not see any difference in the tables comparing to a stock program.

RPM WS6

iTrader: (3)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by RUF SS:
<strong> I have my car PCM done by MTI. I did dyno about 6 times on 2 different dynos with months in between dynos, and all with the same #s (448 to 451 rwhp).

I try to see what MTI did change on the PCM. And I noticed that they did not tune the car from the PE table!! I am confused, everyone says tune the PCM from the PE table but mine is not. It is still making good power, but what was exactly changed, I think it is the high/low Octane vs. RPM and TQ management. Other than that, I do not see any difference in the tables comparing to a stock program. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I too have noticed this. I had MTI setup my PCM before I bought LS1 Edit myself. I compared their tune to a stock tune and saw no changes in the PE table as well. Actually, I saw very few changes anywhere, but the car makes great power and everything works great.

Also, I noticed that they changed very little in terms of TM reduction. Only one table was modifed. They didn't even change max torque. Oddly enough though, I seem to have zero TM (no timing pulled during shifts AT ALL). Very odd how MTI seems to achive their results... Guess they have a few secrets, huh? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />