Alright here's the deal, I own an 89 iroc L98 car, I've been burning proms for it's 165 ecm for a few months now so I'm finally fairly comfortable with the vocabulary. My friend has a 90 chev truck with a single passenger side mounted to4 turbo, a couple of days ago he rolled it and now he might sell me the turbo and manifold.

This is what I kow form searching old posts. The 749 is from syclones and typhoons, which were V6's. It uses a 2-bar map sensor, which will recognize boost. It can be made to work for a V8.

My questions are, where can I find more info on doing a swap of this nature? I'm subcribed to the GMECM mailing list, and I hear people talking about searching the old archives. Where are these archives and how do I search them. Does anyone know if there is some relavent info in the archives?

Where can I find some pinout diagrams of the 749? I assume that I'll be able to retain the stock 165 harness and use some repining to get the job done. I thought I rememberred reading that Grumpy had done a swap similar to this.

Another question I have is will this ecm work in a non-boosted enviroment? If I do this it will have to been in steps. From what I've read it sounds a lot like a 730 with a 2-bar map sensor so it should work fine to swap to the 749 now and try to get it up and running NA. Correct?

Obviously I've got a lot of questions and need some help but the way I see it, I was planning on swapping to a 730 anyway, so I might as well just swap directly to the 749, buy the turbo, run the car NA until I have the 749 up and running, and then when when it's all firgured out try to install the turbo.

Oh yeah, does anyone know of a list that states which vehicles other that the SY/TYS that use the 749.

Any help is much appreciated.
Thanks

 

Try <A HREF="http://www.cruzers.com/~ludis/p4xref.html#1227749">Ludis's Homepage</A>

 

Ok I found a bunch of info on the SYTY.org site, like which cars used the 749, and I read in an old post that the HAC was available for it but I can't find it or the wiring diagrams. It says on the STTY sit e that the programmer98 program is the only one that can be used for STTY's but it looks like tunercat has a version for the $58, can anyone verify that this will work, I think I'll just buy that tdf file just to get familiar, with the variables. From the looks of the acrobat file on it, it has aot of the same tables as the 730 with the addition of the turbo stuff. But I didn't see a place in tunercat to change from 6 to 8 cylinders?

 

Thanks for the link.

 

A bunch of stuff is in the Archives:
www.thirdgen.org/diyefi/ and www.thirdgen.org/gmecm/

Pinouts should be at the GMECM site.

I don't see why it wouldn't work on a N/A app.

The cylinder select is one thing. You may need to modify the Memcal to select 8 cyls. How, I don't know.

[This message has been edited by Brent (edited June 28, 2001).]

 

You need to get the promgrammer 98, since it is a full hac, editor.

I'd use GMEPro for the 749 editing.

730 and 749 use the same PCB, so th pinouts differences are minor.

yes you can use the 749 N/A, but the VE tables have rather poor resolution that way (FWIW). Making boost lets you use the whole table and the car *feels* better.

In the DIY_EFI, and GMECM acrhives there is more data.

 

When did the GM-ECM list start? I can only find archives for 1999 and half of 2000.

Also in some of the old posts on the 749 in the archives there is a lot of talk about peak and hold injectors. I think I need a basic lesson. Are there different types of injectors? Do they require different ECM's to run them. What type of injectors do I have? Will they work with a 749 ECM running a SYTY code?
Thanks

 

Dude, hit the search button & type in syty & hit go. there are a lot of posts that are very specific to your questions. the short answer is Yes, it can be done. Yes, there are people out there running it. Yes, you can run w/a 1 bar map sensor (good idea, btw). & yes the 7730 & 7749 are basically the "same" ecm, so the swap is not that hard. I have not got that far yet, still having to much fun beating on the car as it is & am going to get back to working on the emulator here shortly.

hth's
BW

------------------
Bobalos
aka Bob W.
www.r71camaro.homestead.com
r71chevy@earthlink.net
&lt;&gt;&lt;

 

There are several types of injectors, other then by discharge nozzle.
First is Saturated, they have about 16 ohms resistance, and like to run in the 2-10 millisecond range.
Then there is Peak+Hold TPI type injectors, that are 2.4 ohms, and like to run in the 1-5 msec range.
Then TBI Peak and Holds that are 1.2 ohms, and again like to run in the 1-5 msec range.

You can see where the current draw for the various resistances will vary alot.

The 749 has the guts in it to run 6-8 saturated injectors, or 4 TPI P+H injectors, like when they use it in Quad 4 applications, just have to switch some pins around and add two jumpers.

Yes, you have to match what injectors run off of what ecm. There are lots of *funny* things gm has done. Like the 730 and 165 have been used in both saturated injector mode, and in single TBI applications.

One of the limits of the oem stuff is that you have to change drivers or use an external driver board to run P+H injectors. Like in mine, I had to have it sent out to change the drivers from saturated to P+H, so I can run 55#/hr. injectors. At one time all the large injectors were P+H. The other thing is suggested operating times. Running a saturated injector at less then 1 msec at idle is about impossible, whereas with a P+H they can easily go under 1msec.

 

Thanks for the info Grumpy.

I'm still reading archives, but it looks quite possible.