LS1 PCM on a 96 LT1 turbo motor.

[SS Duramax]

I've got a built LT1 383 with a TC78 turbo and EFI connections LS1 PCM. It runs with the stock LS1 computer tune, but not very well. I'm getting it tuned on Monday and was wondering if there is anyone who has done this and if they would share some tips. Here are the specs to my build.

Cam specs.
224/224 .577/.582 114 LSA
This is the MAF I'm using, but mine is all aluminum. It has the IAT sensor built in. This website has tables for tuning,
http://www.powrmax.com/PowrMAF%20100.html
I don't know what boost I'll be at, anywhere from 10-15psi from what I'm told. I'm not looking for a particular hp or ET or boost level, so whatever springs I'm using now will be fine for a while.
I'm using a LT1 style monoblade throttle body with the LT1 style IAC and TPS sensors. I have a 3 bar MAP sensor.
I have an adjustable fuel pressure regulator set to about 42 psi at idle. Twin in-tank walbro 255lph fuel pumps, one set to come on at about 5-6 psi. Fuel injectors are Siemen Deka 80lb high impedance injectors.
Ignition is a LSI PCM with D585 truck coils (lower dwell time) and MSD wires with iridium spark plugs gapped at .031"
Rockers are crower 1.65.
Springs are Comp 26094-16. Seat load: 178lbs @1.900''_Open load: 459lbs @1.275_Rate: 449lbs/in
I'm using LS7 lifter with about .00416" preload.
Fans are Flex Lite 410's.
Tranny is a built 4L60E with a 2800 stall.
Rear end is a 12 bolt with 4.11 gears.
Compression ratio should be around 9.2:1.

General Engine Specs

1997 .030" over 350 LT1 out of a Pontiac Firebird
230cc Brodix LT1 Cylinder Heads w/62cc Chambers
Fully CNC ported intake/exhaust/combustion chambers
Cometic "MLS" Head Gaskets
ARP Undercut Head and Main Studs
CP Pistons & Pins - 24cc Dish (Approx. 9.0:1 comp ratio with 62cc heads and .040 gasket)
Total Seal Piston Rings
Manley 5.700" H-Beam Connecting Rods
Callies Billet Steel Splayed 4 Bolt Main Bearing Caps
Callies "Stealth" 4340 3.75" Stroke Crankshaft - Internally Balanced
Fluidampr 7.5 o.d. internal balance 740101
Cloyes Double Roller Timing Chain
Canton Road Race Oil Pan, Melling High Volume (10%) Pump Mel-10552, and Canton Pickup
Trickflow 7.3" Chromemoly One Piece Pushrods TFS-21407300

[joecar]

Tune the MAF by applying wideband correction.

Measure rail pressure with reference temporarily removed, and then calculate the IFR (should be flat).

If you use a COS, make the 105 kPa columns of both VE tables the same.

If you use a COS, remember to edit the OLFA table, and fix any out-of-range tables before tuning.

Let us know how it goes.

[SS Duramax]

Thank you. The PCM I have in the car is from a manual and I have a 4L60E, will it still work? I noticed when I took it for a drive, it didn't shift right and the speedo and tach were all screwy, but I'm sure some of that is from my 2800 stall and 4.11 gears. Do I need a COS to fix this issue? If anyone has any more useful tips, I'd appreciate it as it's going to be a long day of tuning tomorrow. Thanks again. I'll forward this to my tuner so he can get a head start tonight.

[Taz]

I take it you are using one of EFI Connections 24x crank reluctor wheels ?

You will need to flash the PCM with a tune from an automatic transmission vehicle (or swap in the segments).

What OS are you using ?


Regards,
Taz

[SS Duramax]

I'm using EFI Connections 24x reluctor wheel and the OS on the tune I pulled from the computer is 12202088. I haven't touched anything with the PCM yet.

I do have a tune from an auto 2002 camaro OS 12212156. So I need to flash this tune into the PCM and then go from there?

[joecar]

Yes as Taz said you need the 4L60E trans segment.

You could copy all your tables to the 1221215 auto trans file, and then full flash this into the PCM.

12212156 opens the door to upgrade to COS3/02020003 or COS5/02020005, both of these have boost fuel/spark tables.


[ with your current 12202088 file, you have to find a matching 4L60E trans segment, and have COS3 as the only upgrade ]

[Taz]

EFI Connection has tunes available for download in EFILive format ... if memory serves they have a 2002 Camaro with 4L60 ... these tunes have had the injector banks altered to work with Gen I firing order ... would reccommend this as a "base" tune for your project.


Regards,
Taz

[SS Duramax]

Were sitting here trying to figure this out. Found out the hard way that Windows Vista doesn't like to cooperate with EFI Live, or maybe it was just cause we needed to reboot the system, IDK either way we are using XP now. We loaded the COS 0202005 into it followed by a 2002 Auto Camaro tune. EFI connection switches the wires around in the harness to compensate for the different firing order of the LTX.

So I have a 3 bar MAP sensor and was wanting to use the MAF for obvious reasons, but it seems we can't. Is there a way to do this?

[SS Duramax]

Thank you guys again for the help.

[ScarabEpic22]

Depending on your computer, Vista and W7 might need to run EFILive as Administrators. Go into the Program Files [(x86) if 64 bit OS]\EFILive\V7.5 and right click the Scan executable and the Tune executable. Click compatibility, then click Run as Administrator. Repeat for the other V8 executables as well.

You should be just fine using a 3Bar MAP and a MAF, the only reason you couldnt use a MAF is if you're moving more than 512g/s of air through it and maxing it out.

[Taz]

... EFI connection switches the wires around in the harness to compensate for the different firing order of the LTX ...

I believe the rewire in the harness is for the ignition coils ... not the injectors. Believe the injector banks are altered .... been a while since I looked at this ...


Regards,
Taz

[slows10]

Efi connection swaps both the injectors and coils in the harness at the pcm pins to fix the firing order. All set to run if using their harness. The only change required in the tune is the reassignment of injectors to banks to control fuel trims.

[Taz]

Now we've got it ... thanks Slows10 ... has been just long enough since I looked at this material that my memory was getting muddled ...

Attached below is one of EFI Connection's tunes - with the injector banks altered.


Regards,
Taz

[SS Duramax]

So I'm back on the dyno today. My tuner says that the MAF can't be used with the COS we are running, so I installed the stock IAT sensor off the old LT1 motor. Its running pretty good so far, but we have just been idling it. Is there a way to use the LS3/7 MAF sensor with my setup? The IAT sensor in the MAF I have must have been fried because it wasn't registering anything. I'd like to use a MAF just to smooth things out though.

[joecar]

The COS's have the ability to run a MAF.

Which COS are you using...?

[SS Duramax]

COS 5. I'm waiting on a wideband to tune it. The tuner seems to think the MAF can't be used.

[joecar]

MAF can be used, unless boost will cause PCM's airflow limit to be exceeded (512 g/s).

[SS Duramax]

Is this tutorial http://download.efilive.com/Tutorials/PDF/Custom%20OS%20Upgrade%20Tutorial.pdf, on page 15, it says that the MAF must be disabled when using a 2 or 3 bar MAP. That's where the confusion comes in.

[joecar]

All the COS's retain MAF functionality...

the problem arises when a boosted application pulls in a lot of air, causing airflow to exceed the PCM's limit (i.e. MAF will peg at 512 g/s).

Other than that, any COS will run the MAF just fine.

[SS Duramax]

Why does the tutorial say to disable the MAF when running a 3 bar map then? I think I should be making between 10 and 15psi.

[joecar]

The tutorial assumes you will exceed the PCM's airflow limit.

[SS Duramax]

So on 10psi it made 600hp and 600ft/lbs. Not super impressive or anything, but I think above 10psi it will start to make more per psi, if the turbo still has some cfm in it. We didn't use the MAF cause the IAT sensor in it was dead, and the tubing went from 3" to the 4" MAF housing and back down to 3.5". So the readings wouldn't really be accurate cause of the turbulence. So I wired in the stock IAT sensor and we're using a speed density tune. So there is a dead spot if I mash the throttle. The is a little hesitation off idle that I think would be cured if I used a MAF. Here is the dyno chart. You can see the lean AF ratio right at the beginning. 12187

Also when I start the car while its cold and put it in gear it dies. So I think the idle needs to be elevated or something.