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I have a '7427 PCM with a BYJL MEMCAL out of a '95 C1500 5.7L/4L60E TBI 4x4. I also have the '7730 ECM/AUJP that came out of the same car that the motor/trans came out of, a basically stock '91 5.7L TPI motor/700R4 that I am installing in another vehicle. I'd like to use the PCM (with the required mods) over the ECM/AUJP.
My question is this: has anyone used the AUJP MEMCAL (with a 512k chip and BYJL.bin) in the '7427? The K/S sending unit is the same for both models, but the K/S filter board is obviously very different between MEMCALs.
I am thinking the AUJP K/S and netres might be a better match for the TPI motor, but the BYJL MEMCAL (with cyl select mod) might be a better match for the PCM.
No, no electronically controlled tranny. I might do away with the EGR and air pump and go with headers, but that will be as far from stock as I will possibly get.
I have been told that the software is more easily understood by a noob in the later truck PCMs, as well as being a better choice overall because of processor speed, ALDL communication speed, enhanced learning capabilities, and other refinements. Am I biting off more than a noob can chew?
Ok, from your latest replies I can see you've been mislead a bit.
I'm sure that the "newer PCM = better" was in comparison to the older TBI ECM being the '7747 ECM, which yes the newer Truck ECM, being the '7427 would be a better option for a TBI vehicle with quicker datastream and a few other refinements.
Now, it sounds like you are going with a TPI set-up and either a non-electronic auto or manual transmission, and if that is the case, keep the '7730 and AUJP MEMCAL, because the '7730 with the AUJP (AKA $8D mask) shares much in common with the later TBI ECM, with the same bit rate for the datastream (8192 baud), use of a MEMCAL that includes the knock filter and Limp Home Mode (LHM).
For what you've said the '6427 would have no advantages over using the '7730, and even if the $8D would work in the '7427, you would likely need to make some changes internally to the injector drivers due to a difference in resistance of the injectors between the TPI and TBI injectors, or make some wiring changes to run all 8 injectors off only one injector driver, but this is territory for an experianced EFI modifier, and not recommended for a "n00b".
Best way to get your feet wet is use the hardware that was designed for that combination, and tune with that, once you understand how it all works and communications then you can start to get into swapping ECMs and MEMCALs, but would really recommend trying it on a test bench before trying it on an actual engine.
__________________ If you're not living on the edge, you're taking up too much space.
Last edited by Six_Shooter; 04-20-2009 at 07:43 AM.
Ok, from your latest replies I can see you've been mislead a bit.
I'm sure that the "newer PCM = better" was in comparison to the older TBI ECM being the '7747 ECM, which yes the newer Truck ECM, being the '6427 would be a better option for a TBI vehicle with quicker datastream and a few other refinements.
Now, it sounds like you are going with a TPI set-up and either a non-electronic auto or manual transmission, and if that is the case, keep the '7730 and AUJP MEMCAL, because the '7730 with the AUJP (AKA $8D mask) shares much in common with the later TBI ECM, with the same bit rate for the datastream (8192 baud), use of a MEMCAL that includes the knock filter and Limp Home Mode (LHM).
For what you've said the '6427 would have no advantages over using the '7730, and even if the $8D would work in the '6427, you would likely need to make some changes internally to the injector drivers due to a difference in resistance of the injectors between the TPI and TBI injectors, or make some wiring changes to run all 8 injectors off only one injector driver, but this is territory for an experianced EFI modifier, and not recommended for a "n00b".
Best way to get your feet wet is use the hardware that was designed for that combination, and tune with that, once you understand how it all works and communications then you can start to get into swapping ECMs and MEMCALs, but would really recommend trying it on a test bench before trying it on an actual engine.
Personally, I would make the changes to the Memcal and Injector driver sense resistor to make the 6427 work in MPFI Saturated mode. I never liked the 7730 ECM as well as the 6427. The 6427 idles better and seems to offer better throttle response.
Let me make this clear: I am working with a 16197427 BJYL PCM out of a 1995 C1500 4x4 5.7L TBI engine with a 4L60e transmission, not a '6427, not a '7747, a 16197427. I don't even know anything about the '6427, or a '7747, or anything other than the 1227730 AUJP that came out of the same car that had the 5.7L TPI motor and 700R4 transmission that I am using.
One or both or all of us is confused, and at the very least, I know that I am.
Now...are we talking about the same thing?
Quote:
...you would likely need to make some changes internally to the injector drivers due to a difference in resistance of the injectors between the TPI and TBI injectors, or make some wiring changes to run all 8 injectors off only one injector driver, but this is territory for an experianced EFI modifier, and not recommended for a "n00b".
Again, it depends on the noob. And I may be wrong, but I think there are two injector drivers in a GM V8 TBI PCM...at least, there are two sense resistors...yes? So only 4 saturated injectors per driver, at 14 ohms or more impedence per injector? Change drivers from peak and hold to ramp and hold? Change to 1/4 DRP? Done all that.
Quote:
Personally, I would make the changes to the Memcal and Injector driver sense resistor to make the 6427 work in MPFI Saturated mode.
Again, assuming we are talking about a '7427 and the BJYL MEMCAL, I've already done this stuff to it, and I understand the theory behind why I needed to do it.
Quote:
I never liked the 7730 ECM as well as the 6427. The 6427 idles better and seems to offer better throttle response.
Again, laboring under the same (mis)assumption ('6427='7427), I been told that, too, and more, which makes this so tantalyzing.
What worries me is all the stuff I don't know yet.
You can always tell who the pioneers are...they are the ones with the arrows in the butt. I don't mind taking an arrow or two, I just don't want to get overwhelmed. Is there enough publicly available knowledge out there to where a noob can pull this off, or is this gonna be doomed from the get-go?
I understand that the name of the forum is DIY PROM, but I'm not an EE. As the saying goes, I'm not asking for a hand-out, just a hand...from the guys with all the arrows in their butts.
Let me make this clear: I am working with a 16197427 BJYL PCM out of a 1995 C1500 4x4 5.7L TBI engine with a 4L60e transmission, not a '6427, not a '7747, a 16197427. I don't even know anything about the '6427, or a '7747, or anything other than the 1227730 AUJP that came out of the same car that had the 5.7L TPI motor and 700R4 transmission that I am using.
One or both or all of us is confused, and at the very least, I know that I am.
Now...are we talking about the same thing?
Again, it depends on the noob. And I may be wrong, but I think there are two injector drivers in a GM V8 TBI PCM...at least, there are two sense resistors...yes? So only 4 saturated injectors per driver, at 14 ohms or more impedence per injector? Change drivers from peak and hold to ramp and hold? Change to 1/4 DRP? Done all that.
Again, assuming we are talking about a '7427 and the BJYL MEMCAL, I've already done this stuff to it, and I understand the theory behind why I needed to do it.
Again, laboring under the same (mis)assumption ('6427='7427), I been told that, too, and more, which makes this so tantalyzing.
What worries me is all the stuff I don't know yet.
You can always tell who the pioneers are...they are the ones with the arrows in the butt. I don't mind taking an arrow or two, I just don't want to get overwhelmed. Is there enough publicly available knowledge out there to where a noob can pull this off, or is this gonna be doomed from the get-go?
I understand that the name of the forum is DIY PROM, but I'm not an EE. As the saying goes, I'm not asking for a hand-out, just a hand...from the guys with all the arrows in their butts.
I had a brain fart. It is 7427 and 8625 that series of TBI PCM that I am talking about. I HAVE run TPI with the TBI PCM and got it running very well.
This was my first startup of the 305 I had running on the 7427. I was running a 4L60E behind it. Being the first startup, all of the calibration tables were a complete guess when it came to fuel. Despite that it ran and even idled, very well. As you can see I still had not even completed the harness modifications and simply had the TPI injector harness plugged into the TBI connector ends.
BJYN (1995 G20 Van 350/4L60E/3.42) Memcal running parts of the BHMC (305 TBI) and BHRD (CPI 4.3) Calibrations.
Sorry I was hitting the "6" instead of the "7", I meant '7427.
Both the '7730 and '7427 are considered "P4" ECMs, and share very similar hardware, from what I have read, just that the '7427 has hardware for electronic tranny control.
In the end, niether ECM as in the hardware should really provide any noticeable difference in idle or the way the engine runs, once either has proper tunes for the engine that it is being used on.
Yes, the TBI ECM will have two injector drivers, where as the '7730 has a single injector driver. IMO niether has an advantage over the other based solely on this. If two injector drivers are really a concern the '7749 could be used which is basically a '7730 with two injector drivers (It is missing a quad driver that the '7749 has though, which shoudn't be a concern anyway).
I think you mean "saturated" when you are saying "ramp and hold".
I'm not following on the "change to 1/4 DRP".
I guess it's just me, that while I do like to experiment, there is something to be said about K.I.S.S. This seems especially true when first getting into stuff like this.
__________________ If you're not living on the edge, you're taking up too much space.
Another 7427 MPFI in SoCal! Read everything on this from HaulnA$$, Dimeneted24/7, Fast 305/355 here and 93V8S10, junkcltr, and others on FSCForum. Your injector constant will be half of what you think based on the DPR scheme. Good luck.
Last edited by gsjmtntman; 04-20-2009 at 03:36 PM.
Dude!! You are exactly where I am with my beast! PM if you want. There is a lot more info around here than when that post done. There is an excellent .xdf from 93V8S10 created pricisely for this. Dimented has the best hac. Read this about when the real research was being done:http://www.thirdgen.org/techboard/di...-its-time.html (TBI guys, its time to update!)
Yes, I have 93V8S10's $0D mask. And yes, I've read that thread...whew! It's a good thing it was raining and I was cooped up in the motorhome when I started reading that one! And it was cool reading as the story unfolded and more and more was discovered about the PCM.
Not sure about being where you are with your 'burb...you are driving yours! I'm still quite a ways from that point...
This seems especially true when first getting into stuff like this. 
Dude!! You are exactly where I am with my beast! PM if you want. There is a lot more info around here than when that post done. There is an excellent .xdf from 93V8S10 created pricisely for this. Dimented has the best hac. Read this about when the real research was being done:
