Hey all, I am a new guy, doing an oddball project and I have many questions. I am desiring to run a turbo setup on a 1987 Chevrolet Celebrity station wagon 2.5 TBI (1227748 C4 type ECM) as a learning experience. I have ordered up a PROM burner and am getting an eraser, and have a copy of Tunercat.

1)I would like to know what it takes to make a naturally aspirated table set (1227748 ECM) work with a turbo type inputs. That is to say, what must I do to the ECM to make it recognize a 2 BAR MAP input when I put the 2 BAR MAP on?

a) is there some cal file that has to be changed to make it read 0-2 BAR over the 5 volt input? Where do I get the values from?
b) How do I expand the tables such as VE and VE adder to encompass Pressures that go over 101.4 kPA?
c) is there enough room on the chip (27C128) for this
d) how do I make the VE tables go over 100% (which I assume they do at some level of positive manifold pressure) I read that the value of VE adder + VE can never be interpreted by the ECM as a value over 100%, at least for the $42?

2) Given that this could be some complicated ****, and is maybe outside the capability of the Tunercat and my never-done-this-before self, could I just run the Turbo Sunbird code and tweak that to engine size and VE values?

a) Is there anything that keeps me from running the Turbo Sunbird $58A code in my 1227748 ECM? What happens when I use a code from another ECM (in this case the 1227749) in my ECM?
b) If this is something I can do, how do I compensate for the fact that the Sunbird is MPFI and my car is TBI?
c) I assume the other constants would just carry over, such as spark bias, VE values under vacuum etc?

This is probably a lot of stuff, so I appreciate any help I can get
Thanks

Kurt Kimmerly

 

a) is there some cal file that has to be changed to make it read 0-2 BAR over the 5 volt input? Where do I get the values from?

You typically need to rewrite the way the code handles MAP input. Things like Baro and vacuum can really be problematic.

b) How do I expand the tables such as VE and VE adder to encompass Pressures that go over 101.4 kPA?

You can either patch the code or disassemble and rewrite and reassemble to expand the tables. Just changing the sensor will rescale the MAP since the tables are ultimately using voltage..

c) is there enough room on the chip (27C128) for this

Depends on what else needs to stay.

d) how do I make the VE tables go over 100% (which I assume they do at some level of positive manifold pressure) I read that the value of VE adder + VE can never be interpreted by the ECM as a value over 100%, at least for the $42?

Boost multiplier seems to be the way to go with this.

a) Is there anything that keeps me from running the Turbo Sunbird $58A code in my 1227748 ECM? What happens when I use a code from another ECM (in this case the 1227749) in my ECM?

I'm not sure whether they share a board but typically masks only run correctly on the hardware they were written for.

If I were you I would take a good look at Grumpy's $60 source code.

John

 

Another part of this project is that I didn't want to mess with the cars factory wiring harness, hence not wanting to switch ECUs. It seems like at least the lookup table or whatever its called for things like the ECT and MAP should be easy to change (at least they appear to be on EFIs like Megasquirt) I guess I am a bit at a loss though. All this code and disassembly and such. I guess I dont really particularly even know the definition of source code, patch, or boost multiplier either, for that matter.

From what I have seen online, the $58 code has more tables that are relevant to a turboed engine than the $48 my ECM has. I assume that the $60 source code that Grumpy has created is the same way. What does it take to implement source code such as the $60 on a different ECM? What does it take to differentiate a distributor engine from a DIS one (I see that the $60 somehow addresses that)

This is going to require learning a lot about programming, hex, and binary, isn't it?

Thanks so far
Kurt

 

So are you saying that one thing I could do (assuming that MAPs are linear) is to shift my values all down on the table to the positions that represent half what they really are and then just add in the boost ones? (for example, take the 100 kpa value and enter it in the table in the 50 spot, knowing that it is really double but that the MAPs output voltage at 50% is really 100)? Will this mess with other things that are manifold pressure dependent, or will it be good as long as I change every table using it to the .5 value?

Thanks again
Kurt

 

You've dug yourself a huge hole, with what you want to do. And taken the position that takes the max amount of work to accomplice what you want to do.

If you want to run boost, then take the answer where everyone's done all the leg work for you. The 749 is fully documented, has patches available for it to make it even more user friendly, and lots of guys are using them.

If you don't want to do mess with the harness, then solder up a little adapter harness. And then you can work out the N/A with the 749 and keep everything plug and play.

I have over a year, and ALOT of time in the 60 Source Code project. Not to mention a few years learning what to do before even starting on it. If you want to take that route fine, but it is more work then you can possibly imagine.

Not to mention with the C3 you'll always be limited to the slow Baud ALDL.

HTH

 

Hmm ok, I think you sold me on this '749 idea.

1) To make an adaptor harness, where does one get the ECM-side connectors that I could plug into the stock harness?
I assume then that I would just match up the pin outs, and I would be set.

2) How do I set up a 749 to run DIS code and turbo code?

3) Are all 749s the same (can I grab one out of a deceased 88-89 Q4 even though its NA?)

4) Will the turbo code run the car NA ok (I would like to take this in steps, to verify my work along the way, strapping the turbo on being last) That way I can verify that the car works right with only the new ECM. Would I just put some arbitrary values in for boost conditions since I would never be getting into those regions?

Thanks so much for the help so far!

Kurt

 

More questions!
I can run the TurboGP 730 code in the 749, right?
Does that save any work over the $60 code, or is the $60 better because its better dissected?

Thanks
Kurt

 

I did a little more looking and there was a DIS version of my engine that came with the '730 ECM. What knowledge and software does it take to make a bastardized program that is part DIS 4 NA cylinder, and part DIS 6 turbo cylinder? Must I know this assembler, or is there some easier way?

Kurt

 

Answers...

1. Best way is too find a dead ECM and desolder the connectors.

2. You will need to change some settings in the bin, (I haven't done this, but I know people that have) and $58/$60 is already turbo/supercharged code.

3. A 749 is a 749. So long as you run Saturated TPI type injectors, a 730 in most cases can be subbed.

4. The $58/$60 has a flag to switch between N/A and Boosted. The MAP sensor will need to be changed for N/A (1 BAR) and Boosted (2 BAR).

 

I would just use a 730 pinned to match a TGP.

$60 is probibly the best disected code other than the turbo regal code.

 

Typically you can change the number of cylinders in the bin to match what engine your using. Then use a corrosponding memcal that matches the engine. (ei 4 cyl memcal= 4 cyl engine, 6cyl memcal=6cyl engine) BW