Jon88GTA

There are many questions floating around in my head regarding these issues. Hopefully I can phrase and order them so that my thought process can be cohesively followed. I am looking for specific, individual answers to each of these individual questions.


1) Does the 165 ECM use the MAF lookup tables when it is configured for use with an FM MAF? In other words, can the '255 g/s limit' be overcome simply by configuring for and hooking up a digital MAF?

2) Does the '255 g/s limit' exist in the 148 code? Is that limit overcome in the 148 by using a digital MAF?

3) Does a MAF ECM exist (prior to LT1) that does not contain the '255 g/s limit'?

4) When a digital FM MAF is used, what frequency range does the 165 ECM recognize? What frequency range does the 148 ECM recognize?

5) Can the Bailey translator (which allows the 148 ECM to work with an LT1 or LS1 MAF: both MAFs are digitial, both read to 512 g/s) be used with the 165 ECM? If no, why not?

6) Could the Bailey translator be modified to work with the 165? Could an external device (a translator for a translator, almost) be made to modify the output of the Bailey translator so that the 165 would work with it?

7) What does the Bailey translator do, aside from simply rescaling the output of the MAF to frequencies that the 148 ECM can work with? If the '255 g/s limit' exists in the 148, how does the Bailey translator overcome it?


I understand that much of this is probably outside of the current knowledge of GM ECMs. I also understand that knowledge on the Bailey translator in particular is tight due to intellectual property, fear of piracy/reverse engineering, etc. I am asking for a lot of info and thus potentially very time-consuming replies; I can only offer my most sincere thanks and appreciation for any information that is shared. Most of these questions will probably remain unanswered; I hope to, at the very least, shed some light on areas where research needs to be done, or prove some potential solutions to be unuseable.

At any rate, if you can answer any of these questions, in whole or in part, please do so. Feel free to substitute '148' with any MAF ECM, and 'Bailey translator' with any MAF translator, if you have information in those areas. Finally, if you can point me to information that might answer any or all of the above questions, it would greatly appreciated.

My sincere thanks again for any and all replies.

-Jon :)

Grumpy

There is circuitry involved so, you can just flip a few switches in the code and have the ecm read another MAF.

The Translator allows the use of the late MAF, but it also gives you and adjustment for idle mixture then various rich/lean WOT settings, along with base timing corrections, and also ramped timing corrections. It's alot more then just a signal translator.

The 255 can be microsnots/ hour. 255 is just the hex value FF. Nothing more nothing less. If you made the scale bigrams/sec you would have your 510 grm/sec..

For the work and expense of changing to something like a Translator you could have gone to a 730 and not have any of those worries.

The 148 guys are stuck with their options. There aren't many alternatives. They are being forced to look at options since the oem MAFs are no longer available.

Grumpy

CAN'T FLIP a few switches
as in CAN NOT,
not enough coffee

Jon88GTA

I wouldn't exactly say that. You can change a software switch in the 165 PROM and it will read an LT1 MAF *up to a point*, this has been done by at least one member here. However, the LT1 MAF's frequency output is in a completely different range from what the 165 was designed to read, hence the need for a translator. I'm not looking to do this by simply rewriting code, some external circuitry is almost definitely going to be needed. Actually, I'm confused as to how the GN guys can do it *without* modifying the code.

Right. I am aware of all of that and, as I typed above, I am completely baffled as to how that can all be accomplished externally, without altering the PROM. I am working under the assumption that the 148 operates, codewise, in a similar manner to the 165; is the 148 really a completely different ECM/code? Is there a hack of the 148 available?

Again, I am aware of that. The bigrams/sec idea has been shot down several times due to the resultant loss of resolution--the MAF tables are finicky enough as it is. Also, changing airflow units would require modifying the math the ECM uses to calculate pulsewidth, which is (thus far) completely uncharted territory, hence my other post on MAF code.

That is your opinion and your personal evaluation of the situation. Opinions change (in your Tuning Tips article on diy-efi.org, for example, you argue that the WB 02 is not neccessary for the average DIY tuner), and personal evaluations are just that. Personal. All of us here have stuck with EFI, rather than rip everything out and put a carb on. Some of us also prefer to stick with MAF, rather than convert to SD. I could argue further, but this is not the place for it.

The 165 guys have *NO* options. I'm trying to change that.

Jon88GTA

Edit: added a sentance to the end of the first paragraph of my first post.

Craig Moates

Microsnots/hour. I like that. On the same line, I still believe in the approach of MAF bypass with a lie for the FI size to get >>255g/s. Granted merit to the nonlinearity and need for recalibration of the scalar tables (potentially). But it could get you right there in a hurry, all that's needed is some ductwork.

junkcltr

iTrader: (1)

Sounds like a good idea for people wanting to stick with the MAF sensor. All that is needed is a flow-bench, o'scope, Matlab, Electronics I & II books, and a few months. I thought about this before and then I decided to go with the MAP sensor. Personally, I thought it was easier or maybe I am just lazy. Without the tools mentioned above....how do you get the analog voltage accurate enough to look like the original MAF. I did a minimal amount of math to figure it out. Unfortunately, I wasn't smart enough. Oh well, that was me. Good luck,
J

Vader

Did someone mention "MAF Bypass"? You mean like this:

Frank88

Vader,

I'll bite - what's the scoop on the mod? Is this your engine? Why did it need the bypass? etc. etc.

And how did you handle the unmeasured airflow issue?

thanks