Newbie question regarding Red/Blue PCMs

[57 Handyman]

buddrow, thanks for providing input to this thread. So, based on what you are saying, the 5925's red/blue connectors will NOT fire the 2 TBI injectors because the BCC (which includes the .bin, .xdf, and . adx are different plus the red/blue connectors are wired differently. Interesting...

With regard to your recommendation of sticking with the PCM my engine came with, all my research/readings online say that it is possible and likely worth the effort to upgrade to the 50x's faster 8625 PCM rather than stick with the slower 4288 ECM that came stock in my '92 4.3L S10.

[buddrow]

It's not so much the connectors themselves as the hardware internal to the pcm as well as the software that runs everything is different.

The '4288 is a direct replacement for the '7747, provided they are both from the same engine size, 4.3,5.0,5.7... The '7747 may not be the best choice for performance applications, but for simplicity, it would be an easier swap than the 8625 since it's a direct swap, no pin swapping. I know this because I have done such a swap in a friends '92 with the '288. The 8625 will run the 4.3L, you will just have to do some pin swapping at the pcm connector. There are wiring diagrams available on this site, or if necessary I may be able to provide you with wiring diagrams for both pcms.

The BCC(broadcast code) is the calibration code name/designation.
the .bin is the actual calibration file
the. xdf is used by tunerpro to organize the .bin file for human viewing, modification, etc.
the .adx is solely for datastream interfacing, datalogging, etc.

These are all different from one pcm to the next, but are the same between different calibrations/.bins of the same pcm number, if that makes sense.
Just food for thought.

Buddrow

[57 Handyman]

Buddrow,

Thanks for your offer to assist me with tuning/reprogramming the 4.3L in my '92 S-10. If the 7747 is a direct swap to my stock 4288, are there benefits to making the swap? Is the internal processor speed higher or the same 160 baud in the 4288?

I am aware of the repining required in switching from the black 4288 connectors to the red/blue for the 8625. I guess my preference for the 8625 is tied to the benefits I've read about on the site and, more so, the amount of work others have already done with the 8625. While I have seen and found a few wiring diagrams, I would appreciate seeing a listing which you have used with success and what your recommendations you'd make regarding sensors, such as O2 and knock sensors. Both of these are the stock pieces and I was wondering if I should be using different ones.

Again, thank you for helping.

[buddrow]

The main benefit to swapping to a 7747 over 8625 is plug-and-play. The 7747 doesnt require any modifcations to the connectors or anything else, its a direct replacement. The 288 has limited support versus the 7747(which is very heavily supported on this site) in regards to xdf, adx, bins, etc. The 7747 is inferior to the 8625 in a couple of ways depending on your perception of things. The 7747 is 160 baud(yuck) vs 8625 which is 8192(9600)baud, this is only noticeable during datalogging/data aquisition though. The 8625 has higher resolution fuel and spark tables which is a benefit, but not a ncessity in my opinion. Ive been running a modded 7747 in my 90 Chevy and to the unaware, you couldnt tell the fuel and spark maps stop at 3600rpm. When it comes to tuning these ecms/pcms, hardware required to do so comes into play. How are your soldering skills as some are required to make updating the bin possible. Time for coffee...:-)

Buddrow

[57 Handyman]

Buddrow,

You've just about got me convinced regarding pros and cons for switching to a 7747. I'm re-evaluating my needs in light of what I've experienced in getting my truck to run smoothly and dependably. At present, it maybe a whole bunch of problems, i.e., vac leak, possible sensor, need to rebuild the TBI again, fuel relay/pump, etc. on top of the internal engine mods I've made...marine cam, .020-in overbore, higher compression--flat-top pistons, 96 Vortec heads, etc. Also, since I wanted to keep the TBI (vs change to a carb), some of these mods resulted in no EGR--the Edelbrock 2114 intake does not have a place for one. Is yours a 4.3L or V8 in your '90 Chevy?

As for soldering skills, I'll be able to do the ones described on this as well as other sites. Now, I also need to find a 7747.

[buddrow]

If it were me, I would swap in the 7747 and be done. Maybe a few tweaks here and there to the cal/bin. When swapping ecm/pcm's, always make sure the net resistor matches the engine family, i.e. v6-v6, v8-v8. Also, you mentioned sensors, you can retain your factory '288 sensors as they are the same as 7747 hardware. You can find the 7747 in most 88-91 Chevy/GMC trucks at most salvage yards fairly cheap(under $50) at pull-a-part places. Pulling it yourself insures what you get, full size trucks had the 7747 in v6 and v8 trim, if in doubt, run the .bin/BCC against the list for the 7747's. And don't fret too much if the truck you get it from is a manual trans and your is auto, you can change between the two in the .bin file with Tunerpro.

Installing the Moates adapter in the 7747 is pretty straight forward and easy to do even with minimal soldering skills.

But before you embark on the swap, verify all mechanical issues are squared away, otherwise you can chase your own tail for days, weeks...:-)

Buddrow

[57 Handyman]

Buddrow,

I am leaning toward doing what you suggest about using a 7747. With respect to verifying the mechanical issues before making the ECM to PCM swap, that is exactly what I have been trying to do, especially, with regard to the EGR. I have been focusing on the EGR because it is the one sensor that I eliminated. However, that being said, I don't exactly know how significant an impact the EGR has on my 4.3L running smoothly and dependably. Additionally, I don't understand to what extent the engine modifications I've described above contribute to the issue of smooth and dependable performance.

Up to this point, I have been unable to take any action on what you've suggested in this thread because I am currently away from home attending Hot August Nights in Reno and will return home in Hawaii on Tuesday. While here in Reno, I have been searching online for a 7747 and have found several candidates. As you may realize, the availability of parts in the islands is very limited. I will get back to you shortly. Again, thanks for your help.