I have a question about this seller I found on ebay:
http://cgi.ebay.com/ebaymotors/90-92...item2c5d8c6908

This guy is selling what looks like a remanufactured memcal that he then fits with a programmable prom, so he can fit it with whatever you want.

My memcal is probably going south, I had extended its life when its prom went bad by using a G1 adapter and my own prom. It's started spitting out bad data again when logging it though and I am guessing the memcal is now really failing.

It's a cheaper solution than trying to get an OEM part (even a refurbished memcal seems to be 150ish) so it's an interesting option I would like to know more about. Has anyone here bought from this guy, or have any tips?

 

LOL, I looked at the pictures and thought it looked like a modfied V6 MEMCAL.... Then I read the description.

There is information on here about the jumper for the hardware cylinder select for V8. With that info, you can make the same MEMCAL for a lot less money, using the very common V6 MEMCALs.

I have like 20 V6 MEMCALS laying around, hmmm..... lol

 

Interesting...
How did they change the limp resistors and make the knock filter work with 2 different knock sensors.
I'm skeptical

 

The only change to the resistors is to jumper pin 56 to ground. This sets the ECM for 8-cylinder MPFI injector firing rate. Can see the jumper in the picture.

The limp mode is a tad rich because the 3.1l engines run with a slightly smaller injector relative to engine displacement.

The knock filter works as it expects a sensor with an impedance of 3.9K ohm. As it being a 3.1l filter, it will not be ideal for a 5.0l or 5.7l engine. Which means that it may pick up more false knock, or not be as sensitive to real knock. But it'll work enough to detect strong knock.

With a center freq of 6K Hz, the 3.1l filter matches a 5.0l filter center freq. However the noise channel gain and offset are a little different.

As for using the 3.1l on a 5.7l engine, lots of differences. Center freq is 5K Hz, first stage gains and offset is quite a bit different. And the noise channel is also quite a bit different.

RBob.

 

That was my first thought. One or the other but not both.
Also the 6 fueling is different by DRP than a V8 IIRC , RFD resistor settings must be FUBAR but workable ?? IDK
I've been digging back into this since I'm ready to install my 406 and would really like to find the mystical $RFDCAL document to id the resistors for limp mode or do some testing to find some answers. With my 406 roller it will put me even farther from running on limp and the KS stuff that I need to work for some Nos routines I'm dreaming up.
Would like to do some heavy bench work on those with JWSCABs board if I can get to it. Need to find a scope though.
New motor is making me ambitious

 

So the concensus here is not to bother with it I gather.

Is there any way to test my old memcal and see whats wrong with it, if anything?

 

Grounding pin 56 of the MEMCAL sets the injector firing rate to an 8-cylinder.

Figuring out the resistor calibration isn't too difficult. I've done it and posted it for the C3 ECMs. Although do need a ECM bench and a scope.

May also be beneficial to figure out which resistor is the RDF enable, and disable the chip. At least you won't need to change the plugs if the ECM goes into limp mode.

RBob.

 

It depends upon what you are looking for. If all you want is stock AUJP and no other tuning, can do it.

If you plan on doing some tuning then no, probably not worth it.

As for your old MEMCAL, what is it doing? Or not doing?

RBob.

 

I've been trying to diagnose my idling problems (and sometimes I get a service engine light after driving a while). I've checked for vacuum leaks and found none, the TPS measures .61v at idle, I understand thats good enough. I also just swapped the injectors since they where bad and while that made the car drive pretty great the idling issues remain.

So I decided to datalog it and see if throws any codes, but what I got was some pretty strange readings (datamaster reported many checksum errors). Showed it to someone and he said my ECM was spitting out a lot of rubbish. Could be the chip, memcal or ECM.

I know the chip/memcal has had problems in the past, I managed to fix that many years ago by putting a G1 adapter + burned chip with factory settings into the memcal. That seems to have stopped working now, maybe it's just the chip, or its the rest of the memcal going south, or the ECM itself.

Its true that I just want to run it stock, though I figure I should tweak the injector settings since the new ones are 24lb/h.

 

I plucked out the chip today and had a look at the data on it, looked like gibberish. Reburnt the chip and tried again, idling problems are gone. Took it for a drive and after about 7-8 miles it sets of a Code 32 or EGR system Fault. I logged the way there with TunerproRT and the return trip with Datamaster (it seems easier to find the DTC codes in this program). I can upload them both here for people to see. There where still some Engine Data checksum errors though, but not as many as there used to be.

 

Cause ,supposedly if you use a v6 memcal (TBI 4.3 Liter), they are close enough to the v8.

 

Question about the logging, is it normal for there to be a few engine data checksum errors, or should there be zero?

 

Gary is great. I bought 7 memcals from him and run them in all my cars. No complaints and super fast communication.

 

I am the seller of these re-manufactured chips. I've sold approximately 40 of them with no complaints.

When I first started on a project building a custom 1964 Corvette with a 1992 350 TPI engine, I was shocked at the cost of a Memcal just to start my car up. I did a lot of research on this and other sites to find a low cost solution to the problem. This is the result. A low cost solution that people can use to at least get the car started and to begin tuning.

As the ad says "All of the hard work is done for you". With the labor of finding compatible chips at salvage yards (getting rare), removing the old chip and re-soldering, installing jumper, programming and shipping, I'm certainly not making much on these. My goal is to help people if I can. I spend hours on the phone and email with people about their projects and problems even if they never buy anything. I do it because I like to help people that enjoy the same hobby as myself.

All of my re-manufactured Memcals are bench tested and the run logged for one hour before shipping. All of the V6 chips families that I use have been test run in my car in limp home mode to insure that it works sufficiently and will not damage the engine. I am very clear that the limp home mode is slightly rich but does work enough to get you home.

The knock sensor in these is not as sensitive but lets be real, if the motor is modified at all or even has lots of miles on it, the knock sensor on even a stock setup is not very effective.

I hope this clears up any questions about my re-manufactured Memcal, it's use and the purpose of my item. It's not the real thing but close enough for most uses.

 

Thanks, and you are a great Customer and now Friend.

 

Thanks 91. As far as I can tell they are almost identical.

 

In my opinion, the knock and Limp would not work too well on your 406 roller anyway. You will probably need to disable the knock in programming and limp will be way off as well. Do you ever expect to use Limp home mode?

 

Is your EGR functioning? Disable error word in code and don't worry about it.

 

I say go for it! You'll soon see there is no money to be made there. LOL

 

Hi Gary,
I don't plan to use limp but with custom code things can happen.
Because mods of high fuel pressure and larger injectors, it wets my 350 plugs quick if I don't run the MSD box. Thats with the V8 memcal and I wasn't sure how close the V6 settings would be.
Just hoping it can get figured out someday before I really need it far away

Nice of you to explain what you do have there and it is a good price for the effort.

 

My EGR probably isn't functioning, so if I disabled the error code the idle problems and occasional stopping when I put the engine into gear would remain. I figure my memcal is OK though since it got a lot better after I reburned the chip. I guess it's either the EGR valve or solenoid. Seems like its a lot of problems finding the latter part.

 

It's been a long time since I made those boards up, and even longer since I really messed with this stuff, and I have probably mentioned this in old threads, but as far as the rfdcal, and knock sensor, these are the things I know.

I played with the resistor networks a bunch of ways, just poking resistors across in parallel to change the timing of the circuits, but was never able to get any meaningful changes to the injector or spark timing pulses. really need that 'mystical' document to understand what those resistors are doing, I figured as part of an analog network, you would be able to see the pulses travel through the network, but almost everything I scoped was just different voltages with no real correlation.

the 350's and 454's used the same knock sensor, with slightly different gain settings in the memcals, so a 350 knock module is probably close enough for the 406. you might have better luck making a frankenstein with an Lt1 or Lt4 knock module stuck on either one of my boards, or an original memcal.

there exists an IC that is microprocessor controlled which I *think* is used in newer ecms, lsx, who know what else, that is a configurable knock processor. gain, center freq, Q, and a few other parameters are available, it's also a dual processor. if you can build a small pic/micro board that spits out the few bytes needed to program it and receive the sampling and spit out a gated signal, you could make a configurable all-in-one knock processor.

Texas Instruments TPIC8101, available at digikey for about $7.50 each.

 

i'm thinkin about buying one from him myself, why 7 memcals, was they for different cars

 

Yes they were for different cars. I did a group buy for people in my area. I only have 2 right now, one for my auto set up and now another for the 5 speed swap.