Help with tuning an unusual turbo tbi project.

[scottyd]

Hi, my project is a 52 Chevy that I installed a 250ci inline six in. I have a 79 Buick regal turbo unit mounted on the intake for fuel delivery and a throttle body from a 4.3l v6 i figure that would be a good starting point since overall the inline six is 4.1 liters.

My harness is from a 94 pickup truck, the ECU is a 6395.

I've got it wire up and running (easier than I anticipated)

FOR MY TURBO, Can I use a turbo bin with this ecu? I purchased a 2 bar map sensor... and have been researching Tunerpro and getting myself familiar with the program. I have a aldl cable on the way...I plan on getting an ostrich 2.0 for real time tuning.

As of now the car runs surprisingly good (although i have not driven or ran it long for fear of running lean with boost) I'm using an Airtex fuel pump its rated at 135psi. If i cant tune for boost in the ECU i have tossed around the idea of getting an FMU to put on the return line to manually raise fuel pressure to push the injectors harder during boost... which is commonly done in supercharger and turbo applications but I have a hard time accepting its a safe alternative.. lol

I love this forum btw, have lurked for a while when getting all my parts and stuff put together.

[dave w]

To the forum.

I think the 16196395 is capable of doing boost with a 2 bar map. Both 1 bar and 2 bar map sensors provide 0 volts to 5 volts input to the PCM. The fuel and spark tables respond to the 0 volts to 5 volts input from the MAP. Using the 2 bar map will provide a map sensor voltage to the computer when boost is present. The overall map sensor sensitivity of the using the 2 bar map will be slightly less when boost is not present.

I think stock fuel pressures (less than 30 lbs) will work fine with the stock injectors. There might be a challenge tuning the 6 cylinder with enough fuel at WOT Boost, and possibly having to much fuel at idle? The 16196395 has the tuning advantage of having two fuel tables and two spark tables (near idle / off idle) which will help tuning the fuel at idle and WOT Boost!

dave w

[scottyd]

Thanks Dave, in the bin sticky it says

"16196395 PCM Information $OE This PCM was used in 1994 C/K Truck, Van, 5.7L & 7.4L (HD) 4L80E Auto Trans or Manual Trans.

Also the 16197427 came in these trucks as well and it will run $31, $OD, $OE, $E6 mask"

Does that mean the 6395 also uses those mask? or do both the 7427 and 6395 use them?

[dave w]

TBI computers 16197427, 16196396, 16168625, and 16156930 can interchangeably run the following Masks $31, $OD, $E6, and $OE.

$31 and $OE were usually 4L80E.
$E6 and $OD were usually 4L60E.

dave w

[scottyd]

Ok that clears up quite a bit, I am having a hard time finding much info and files on the 6395

edit*
Just found this:
16168625/16197427/16196395/16156930/16245358

$E6 16168625 93 C/K Truck, Van, 4.3L, 5.0L & 5.7L
$0D 16196395 or 16197427 94 - 95 C/K Truck, Van, S-10 LN2 (16168505), 4.3L, 5.7L & 7.4L
$0DA 16196395 or 16197427 94 - 95 Truck, Van, 4.3L L35 CPI
$0E 16196395 or 16197427 94 C/K Truck, Van, 5.7L & 7.4L (HD)
$31 16197427 or 16156930 95 C/K Truck, Van, 5.7L & 7.4L (HD) 95 - 96 Hummer H1 (Gas)
$8C 16245358 16197427 95 C/K Truck, Van, 4.3L 94 S/T Trucks, L35 4.3L
$8CA 16245358 95 Truck, Van, 4.3L L35 CPI
$63 16197427 96 - 97 C/K Truck, L05 EXPORT ONLY

[1project2many]

Sounds like a cool project.

I think you'll decide increasing fuel pressure with boost is the best option. But injector choice is important because some of the TBI injectors just don't operate correctly if pressure gets too high.There was an individual on j-body.org several years ago that built a nice TBI turbo setup. I believe his username was oneredry. He used the later, small body GM injectors which can handle higher pressure and are available in some extremely high flow rates. I have a spreadsheet saved with flow and pressure data for these injectors, and it may be available on this site somewhere.

[96lt4c4]

I am getting ready to run boost on my Blazer, was TBI, converted to MPFI. Look up a stock bin for a GMC Cyclone or Typhoon. Take a look at the spark tables to give you an idea of what you will need to do with timing. You will have to run less timing under boost.

And yes you will have issues if you try to run too much pressure on stock Rochester GM injectors. I tried it with a set of stock LT1 injectors and at 60 pounds they stopped flowing fuel. The newer slim body Bosch injectors will handle over 60 psi of pressure. My LS1 Fbody runs 62 pounds. If you run out of fuel you may try a set 60 pound 350 TBI injectors or even the 454 80 pounders.

[scottyd]

The more i think about it the more I am considering going old school and putting a resistor on the 1 bar map to limit voltage while in boost and running an extra fuel injector off a Hobbs pressure switch manually programmed to come on under boost. I read an article about it and a guy recommended using a NOS fuel solenoid which can be tuned with jets... that or a cold start injector. Timing can be retarded using the ecu still.

Hopefully my ALDL will be here soon so I can at least run the car and see where I am as far as my 02....

[scottyd]

Well i think I am hooked... All of this is very intriguing to me. Does anyone wanna look at a couple of XDL files and tell me what i might initially try to smooth-en things up until my ostrich arrives?

[delcowizzid]

theres no need for dodgy backyard hacks nowdays so many choices for boosted code and 2/3 bar map sensors.you need a 2 bar to pull timing as boost rises no matter how you do fueling.ide go multipoint if it was me i just finished a 202cube inline 6 turbo which is probably very similar to the chev inline 6.running 3 bar map and 6X60lb injectors that are allready at 50% dutycycle on 7psi of boost LOL

[scottyd]

Delcowizzid, What ecm and bin do you use for your engine?

Is it normal for tunerpro to not hold steady values during datalogging. Mine is pretty dang rough, Idle is bouncing all over ect.

[delcowizzid]

i use 1227165's pretty exclusively for all conversions unless i need to run electronic auto.
values jumping all over could be wrong adx for the vehicle your logging

[Six_Shooter]

Also no need to ad a resistor or zener diode (like the Honda guys do) to the MAP sensor, because the voltage will max out at 5V anyway.

I agree with Dlecowiz though no need to go hack back yard gonna give you problems way of doing things.

[scottyd]

Id much rather not do the crude stuff... I've got an ostrich on the way and have been studying the $od bin and xdf file for a 4.3 v6. The erratic readings I'm getting now are because the fella who sold me my parts was wrong about my chip being a 4.3, its actually a 5.7 v8 prom. Kinda hard for the ECM to figure out what to do with 2 less cylinders lol..

Ive got a 2bar map, and i understand that there may be ways of adjusting the AE or PE tables to help with demands during boost.... I just dont know where to start as far as what to do with making adjustments to make the 2bar work during no or low boost.. (ie divide or double values ect) This is all new to me.

I've also kicked around the thought of using some of the tranny controls (im not using an elect tranny so i have no need for them) to control a fuel solenoid or extra injector based off of RPM or maybe vacuum/boost.. seems probable.

[Six_Shooter]

You would be better off swapping to a different ECM and code that natively supports boost, such as a '7730/'7749 with $58 or $59, especially in light of you not needing transmission control.

You would also be better off switching to MPFI, that $58/$59 also supports.

I have toyed with the idea of using $59 with TBI, but it hasn't been proven to work, and I don't actually own any TBI vehicles currently that I can test the TBI use on. There has been some encouraging information posted on TGO lately about using $8D with TBI and since $58/$59 are sorta related, then I can see TBI working just fine.

The biggest issue with TBI and boost is the fuel enrichment. Since there are only 2 injectors and are not manifold vacuum referenced it will take modification to the fuel delivery system to raise the fuel pressure in relation to the boost pressure and also have injectors large enough to support the power level during boost. People that are naturally aspirated have difficulties getting enough fuel to the engine as it is.