I have several V8 memcals from TBI pickups and vans using the '427 and similar ecm's and can get plenty more, but of course have a hard time finding v8 memcals from 730-727 ecm's.
The obvious question here is, can I use the later v8 memcals for my SAUJP and code59 based projects?

Has anyone tried this?

 

i really don't see why you couldn't... i mean the PROM is in the same place, the knock filter is in the same place, the NETRES are likely configured the same....

 

yeah, I figured as much on the knock filter, and the prom is obvious but I guess the netres is the part I should really be asking about.
Perhaps I'll have to go and fill in that excell chart which was posted a few years ago with my measurements.

 

Well, I tried it. I immediately got a "cylinder select" error.
Setup was as follows:
'727 ecu, 305 TPI, BDJZ memcal ($E6 '93 suburban 5.7L 4L60E) , SST 27SF512 saujp4 1026 = FAIL

It starts with that memcal, but runs bad, and gives me a SES light. TP5 shows "cyl select error". Otherwise with the P4 V8 memcal it runs fine without errors.

Thankfully I have the one original $8D memcal now sporting a 27SF512, But I was hoping to use one of the many P6 based memcals I have as a backup.

At any given time I can find a half dozen 93-95 V8 GM pickups at the local pick-n-pull's, but ALMOST never a V8 '730. Figuring out a practical alternative to an original V8 P4 memcal would be nice.

 

You'll likely need to do the cylinder select hardware jumper, like people are doing with the V6 MEMCALs.

I've been meaning to look more into this, but this pretty much confirms my theory of being able to use the '7427 MEMCAL for TBI applications in a '7730. Still on my list to test fully though.

 

I thought I wouldn't have to do that since the memcal was from a V8 already.

To me the big thing about finding a V8 memcal substitute for P4's isn't really the netres, We can easily reproduce those inexpensively. The ESC board seems to be the main thing.

This winter I have 3(possibly 4) efi conversions to do(for family and friends). I have several 730/727 ecu's and lots of harness making supplies. The problem is finding reasonably priced V8 memcals.

Perhaps I should just setup the harnesses to use external knock filter modules which are readily available C3 TBI setups, and use memcals with no knock filter modules at all? Anybody successfully done this?

 

TBI is a setting all of it's own, so it would make sense that the RFD also had a TBI resistance.

The $0D knock filter should be good for the V8 with the V8 knock sensor. All you would have to do is use one for the truck that the MEMCAL came from. It's possible that it's the same KS as the MPFI/TPI V8 KS.

I'm looking at using the external knock filter on an ECM swap I am doing since it already has the external knock filter, being a Turbo Regal, with a '7148 originally.

 

YES of course! The TBI setting being different than a 4-6-8- cylinder select, dang I should have remembered reading that before. Looks like I'm going to try this again next time I get a chance.
Thanks

 

Do a search for a thread with the title "Question regarding 165 to 730 conversion" RBOB posted the info to use an external knock filter on the 7730 ecm in that thread. Ihave been running an external knock board for several years now based on the info in that thread. I don't recall it being discussed here before but what about the Corvette memcals, are the netres circuits the same as our f bodies?

 

They should be very similar. Other then the heads on some years they are the same engine. The MAF y-bodys used the same ECM as the f-bodys ('7165) And the SD y-body ECM ('7727) is a '7730 PCB with different connectors and a weather tight case.

RBob.

 

Here is the direct link to the thread i was referring to in my previous post
https://www.thirdgen.org/forums/dfi-...165-730-a.html
I forgot i changed the title when i saved it to my harddrive. Thanks for the info about the Vette memcals RBOB.

 

I did a search, and this is the closest thing I could find.

https://www.thirdgen.org/forums/dfi-...165-730-a.html

How exactly do you have the external filter wired in?

I'm thinking of 2 possible ways to do this;

1. Wire the external knock filter into the harness.
2. mount the external knock filter to the 730 case and modify the memcal to have the ability to plug the filter into the memcal, replacing the original knock filter with a little perf board and header pins. So when you plug in the memcal to the 730 you also connect a little plug to the top of the memcal for the knock filter.

Am I thinking strait on this, or have I overlooked something?

Also, I have read some people say that the knock sensor/filter pair are tuned to the bore size of the engine. So according to that can I assume that a 4.3v6 and 5.7v8 can use the same filter?
If so, that would seem to me that if the netres is not an issue and you take care of the right hardware cylinder select resistance you should be able to use a P6 memcal from a 4.3 TBI on a 350 with a 730-749-727, since the knock filter will be for a 4" bore engine already ????

 

The external knock module output goes to an ECM pin, not the MEMCAL. This is pin B8 on the ECM.

As for ESC filters, it is allegedly by bore size. Since that determines the frequency that the bell rings. However, there is evidence to the contrary. Such as marine engines of the same displacement (BBC's) having a different bandpass and center frequency then an truck engine filter.

I don't get hung up on having the "exact" filter and sensor anymore. What I do look for is a lack of false knock reporting. With the proper tune and fuel, knock isn't or shouldn't be an issue.

RBob.

 

Okay, B8. I am assuming B8 is normally unused(I dont have access to a diagram at the moment).
So when using an external filter wired to B8 should you remove the existing knock filter from the memcal (if it has one)?
I used to be able to find Delco ECM circuit board schematics on the web real easy, now I cant seem to find them, were they on one of the GM ECM reference sites that recently closed?
Anyhow, thanks.
Marvin