LS4 / F40 swap - fieroguru (Page 73/216)
blander66 APR 01, 07:55 PM

quote
Originally posted by fieroguru:


The rail/injectors won't be installed long enough to worry about a better spacer method. They are just installed until I dial in the MAF.

The reason for going back to the stock injectors is just to reduce variables. While tuning the MAF you log STFT and the HZ on the MAF and make changes. If either the MAF or injector flow is off, it will change the STFT value. Keeping the stock LS4 injectors/fuel rail should help minimize any fuel flow induced variation as I calibrate the new/larger MAF.

Once I think the MAF is dialed in, I will change to the larger injecotrs and log some STFT at a specific MAF hz value accross a wide range of MAP values. Since the Gen 4 LS engines do not use a vacuum referenced fuel pressure regulator, the flow rate of the injectors change with manifold vacuum. By logging the STFT for a fixed airflow rate across a range of MAP values, I can then tweak the IFR tables to have a consistant STFT across all MAP values. Once they are the same across multiple MAP values, then the remaining STFT delta is most likely MAF related and it will need to be further tweaked.

You can do this process starting with the LS2 injectors, but I think the base LS4 IFR tables have a better chance of being closer from the start, which means the initial calibration of the MAF will be closer from the start.



What injectors are you going to? I have a lot of injector spec as in the IFR, voltage offset etc
fieroguru APR 01, 08:22 PM

quote
Originally posted by blander66:


What injectors are you going to? I have a lot of injector spec as in the IFR, voltage offset etc



Stock LS2 injectors. I already have all the specs/tables, but thanks for the offer.
diabloroadster APR 02, 01:13 AM

quote
Originally posted by fieroguru:

Been having quite a bit of fun dialing this swap. The STFT in the lower MAF table are now within 0.7% and knock free (so far to 4K RPM and 80KPA). I am now running the CTSV 6 speed manual timing tables and ended up pulling .5 degrees of timing from about 10 cells.

Still working on the hanging RPM when I stab the clutch... might need to reduce the throttle follower settings.

Might tray to take a few more videos this week if the weather cooperates.




Is your IAC functioning correctly?

ericjon262 APR 02, 01:21 AM

quote
Originally posted by diabloroadster:


Is your IAC functioning correctly?



he's DBW, he doesn't have one...
fieroguru APR 02, 06:29 AM

quote
Originally posted by diabloroadster:
Is your IAC functioning correctly?




quote
Originally posted by ericjon262:
he's DBW, he doesn't have one...



Correct, no IAC, just a 90mm throttle body that isn't closing fast enough when I push in the clutch and let off the gas. I am going to redo my Base Running Airflow adjustments now that the MAF is dialed in for the low table and switch everything timing related to the CTSV values. I can make it close faster by adjusting the throttle area scalar higher, but then is hurts idle quality. The area scalar is supposed to the the open area of the TB and I have it set to the correct values for the 90MM LS2 throttle body. Zeroing out the throttle follower also brings the RPMs down faster, but hurts launch performance quite a bit. Maybe I need to keep it down low and zero out the upper end... lots of trial and error.
aaronkoch APR 02, 09:35 AM
Not sure where I remember this from, but don't modern dbw engines intentionally idle down slowly to reduce NOx from when the throttle snaps closed? Is this what you're fighting?

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Build thread for my 88 + 3800NA swap

fieroguru APR 02, 02:22 PM

quote
Originally posted by aaronkoch:
Not sure where I remember this from, but don't modern dbw engines intentionally idle down slowly to reduce NOx from when the throttle snaps closed? Is this what you're fighting?



Yes and Yes. The automatics also drop RPM slower and since I am using an automatic calibration with a manual it is particularly annoying. I need to keep the automatic calibration for DoD, so I am trying all the adjustments within the Electronic Throttle parameters to get it to drop RPM much faster.
dobey APR 03, 04:06 PM
Are you running with Torque Management enabled? If so, pulling those numbers back a bit might help. Don't know if the program you're running at the moment has it or not, but I know it does make the trucks feel a bit weird at times, and cutting the Torque Management back is a very common thing to do on them.

Also, I was wondering if you know much in regards to the e38 vs e67 ECMs. I have an e67 already that I was planning to use, but don't have a harness for it. However, a squirrel chewed through the harness in my truck, which had to be replaced, and I got to keep the old one, so I have a harness for an e38 that I could use to build the harness for my LS4. Do you think I should just grab an e38 ECM, or try to find a harness for the LS4 or LS2 to build up and use with the e67 ECM? Buying the ECM and using the e38 harness will of course be cheaper at this point.
ericjon262 APR 03, 04:51 PM
from what I have looked at between auto and manual bin files, torque management is almost entirely disabled in the manual bin compared to the automatic. mind you, I'm looking at older V6 PCMs, not the newer DBW stuff.
fieroguru APR 03, 08:47 PM

quote
Originally posted by dobey:

Are you running with Torque Management enabled?



Torque Management is completely disabled.


quote
Originally posted by dobey:
Also, I was wondering if you know much in regards to the e38 vs e67 ECMs. I have an e67 already that I was planning to use, but don't have a harness for it. However, a squirrel chewed through the harness in my truck, which had to be replaced, and I got to keep the old one, so I have a harness for an e38 that I could use to build the harness for my LS4. Do you think I should just grab an e38 ECM, or try to find a harness for the LS4 or LS2 to build up and use with the e67 ECM? Buying the ECM and using the e38 harness will of course be cheaper at this point.



I haven't looked at the E38 ecm's much at all yet. It looks like the E38 uses 2 of the 3 connectors that the E67 uses. The pins are likely the same and it shouldn't be much of an issue to repin them to the E67 configuration (and buy the blue E67 connector that is missing). I would stick with the E67 since I will have most of the technical aspects of using one figured out shortly. The E38 will be a larger learning curve.


quote
Originally posted by ericjon262:

from what I have looked at between auto and manual bin files, torque management is almost entirely disabled in the manual bin compared to the automatic. mind you, I'm looking at older V6 PCMs, not the newer DBW stuff.

.

In the newer ECM's TM is still there even with the manuals, just different values. The exception is the GM Crate Motor ECM's, they have the TM tables disabled (or alteast the GMPP LS3 E67 has them disabled).

The good news is I am making progress on the slow decline of the engine RPM's after letting off the throttle when stabbing the clutch.
In Idle, Airflow, Throttle Follower, Airflow Step Down: I quadrupled all the values in the table. This made a small improvement
In Idle, Airflow, Throttle Follower, Torque: I doubled all the values in the table and this made a huge improvement, but caused some drivability issues launching right off idle. So next I left all values stock below 1200rpm. The ones above I multiplied by 1.5. This fixed the launch issue, and made an significant improvement in the throttle decline speed (but not as much as doubling it).

I still have a few more rounds of tweaks to dial the speed of RPM drop, but I am at least making progress!