I'm still trying to program my prom! But I was wanting to know what tables do I need to adjust for timing & what tables for fuel. Just trying to make sure I don't adjust the wrong ones, adjust ones that didn't need to be adjusted, or don't forget any that do need to be adjusted. The car is a 92 mpi 350 that I'm adding a blower to.
:rolleyes:

 

:seeya

 

Thanks, but that didn't help much!!!!!!!!!!!!! I'm not seeming to get any answers no matter how I ask. :boxing

 

Don't get me wrong but there is quite good FAQ's on this forum that you could start out with.

PS
And try "Search" it helped me out a bunch of times.

Good luck :)

 

SEE, STILL NO ANSWER!!!!!!!!!!
I have read what I can find but it would still be nice to have SOMEONE answer my question so that I might make sure I am doing it right!
:boxing

 

I'll play devil's advocate here and ask the following...how do you know something needs to be changed?

Without any scan data, plug readings, etc...it's hard to tell someone they need to change something that might not need to be changed. It's like asking someone if they liked the show you watched last night. Give us a hand and at least tell us what channel you were on ;)

 

Well as I mentioned I am adding a blower so timing will need to be changed and I'm adding 2 bar map and bigger injectors so I need to make changes for them. I know that isn't much detail yet but at this point everyone is trying to ask every little detail about the car, but no one has offered any info on the timing. I'm asking people what I should set it to, I'm asking were I go to set it. To me that is a question that someone should be able to answer without needing to know what color the car is! :D After I find out what and where I need to change for the timing, 2 bar map, & injectors. Then I will post to see if what I set it to is correct. :thumbs:

 

Well, we do need an "overview" of the setup first.....and then as an axample on timing-it depends on the scan data-how much knock retard are you seeing?
You must have a scan tool/or software to tune!
Also-you state that you're adding 2bar map-what ecm/tdf? Or aftermarket???
Sorry, but we really do need more input....

 

The ECM is a stock 16159278. And why do you need to know the scan or knock retard to know where to change the timing. I'm not asking what to change it to, just where to change it at! I was wanting to make sure I'm in the right spot and all the right spots!

As of now I'm still trying to get my scan tool to work. I haven't had much luck yet! So for right now I'm just trying to learn more about the tables on my eprom before I move parts that I shouldn't. I moved the timing, just as a test, and it seemed to go alright. BUT I was wanting to know if there was any other tables that I should move to keep from causing trouble.

 

People are TRYING to help you.
It might be better for you to answer some of THEIR questions since YOU are the one that needs the answers.
If they want to know what color your car is..... tell them!!!
What's the big secret??

 

Then why are they asking more questions instead of answering my question. If I was to ask you what to change the spark and timing to then I could see you needing to need more, but I not asking you to tell me what to change it to. I'm asking what table need to be changed to change it!!!! I'm trying to learn but so far everyone want to learn about my car, but that doesn't help me learn about programming the eprom! Sorry but I hav asked four different question on this forum only to have someone to ask more question, but at this point NO ONE HAS ANSWERED ANY OF THE QUESTIONS. at this point I'm just trying to get help learning!

 

You can't just add a 2 bars map sensor your stock ECM and expect it to work. Your stock 1 bar map sensor read from 0-5V which correspond to ~30in hg to ATM pressure (0psi) At ATM it reading 5V with a 2bars map sensor 0psi is 2.5V (its ouput is still 0 to 5V but it corresponds to 30in hg and 15psi).

You can recalbrate your fuel curve to squeeze the map table down however if you look around your ECM parameter (and if you have dissambly of the source code) you will notice a lot of calculations are based on the map (load) value, so everything is thrown out of whack (EGR, Torque converter lock up, timing table, etc.) A good portion of your ECM function will need to be scaled, this is a big time job. You may want to think about switch to a 2bar ECM aka 749, but that will need to be tuned also your would be strating from scratch with factory v8 'close enough' calibration to start with.

 

I've heard that about he 2 bar map, but I'm not ready to give up and swap out ECMs. Once I learn all I have to change for timing and all I have to change for fuel, then I can learn all and what about the 2 bar map. I can't swap the ECM for two reasons , 1 - I will lose my dash gauges (and don't want to) 2 - I don't have the money! BUT more importantly Thats is the easy way out and if everyone (or at least me) takes the easy way out and just replaces things with one that your told will work, then you still don't learn how the old one worked and how to adjust it!!!!!!!!!!

 

Now for a dumb question!!!! Sinse people are suggesting to use ECM 749, are the eproms interchangable? I didn't think so but I thought I would ask. Also if I was to get the bin for a 749, could I just go into the map and related tables, and go from table to table to make them match! If there tables are set for a blower, can I just use thier tables?

 

The 749 is a 128K bin as oposed to your 256, but you can use the eprom if you double up the bin or burn the bin starting at 4000 Anyways I don't think you would lose all your dash function, but I am not 100% sure. In the older c4 (84-89) the gas milage function the only function lost.

As for you can use the stock syclone/typhoon bin, I wouldn't because they would probably be to rich. They use 33lb/hr injectors and they are almost at 100% duty cycle at wot (in addition not a lot of timing is used and the cam shafts are really small compare to stock corvette's.)

 

I'm not sure if that was a yes or no! Plus I'm using 40lb/hr injectors!

 

Can I make a suggestion here???
To get a good idea of the theory of the gm system-it'll make a lot more sense what all folks are saying here then....take a look at a book-"How to Tune and Modify Chevrolet fuel Injection" by Ben Watson......

 

I make sense for what people are saying but I'm just asking what tables to adjust for timing and what tables to adjust for the bigger injectors, and what tables to adjust for the 2 bar map. But everyone is suggesting buy a spark retard or a different EMC. Well all thoughs suggestions may work, there not the answers to my questions. It maybe what they would do if they were doing this project, but they still don't answer my questions. Sorry! But I've been looking for advice on adjusting my ECM, and to learn more! Only to get suggestions on what they would do, instead of information I can use to learn what I need to adjust. Sorry again but I am on a tight schedule only to get none of the information I was looking for! So far the only thing I have learned is that most people would buy a spark retard and replace the ECM, but that doesn't really help ME!

 

I'll give you a few vague answers, suggestions... as I'm only familiar with the LT 1 edit which I used in conjunction with my loging program Autotap... my system uses flash rather than the eproms thet your system uses...

The reason there seem to be more questions asked rather than answered is everyone here wants to give you the very best information possible...

The questions arise like how much boost are you running will you use an intercooler... are you going to run a auxilary fuel enrichment computer?

As you have probably read these all effect how you time and the fuel mixture. I started with an MDS 6BTM and used it to retard the timing to handle the detonation and give better spark etc. Which I suggest you use... as the stock rev limiter (which i set higher than the MSD box) can cause you severe damage if it starts cutting fuel when you are WOT and full boost... I also in addition to larger injectors used a Carroll Superchargering superfueler with a 2 bar sensor to increase the fuel pressure while under boost monitoring the O2's as I made my passes... to eliminate the need for reprogramming EVERYTHING for a 2 bar MAP.

As i got the car closer in to being dialed in, I THEN went into the timing and looked at the KPA RPM and ignition timing settings and flashed the changes to include the retard of up to about 6 degrees starting at about 80 kpa to 100kpa... from there I totally zero'd out the retard on the MSD and used it for the multi spark under 3000 rpms and the soft touch rev limiting... as the cars system was no reflecting the spark curve ...

This is going to be different on every car and every situation as the gas you run, the temp the amount of boost you are running , again whether it is intercooled all comes into play...

In terms of the fuel settings, I left them stock as you in most cases will need to add fuel. This was taken care of with the Super fueler, under full boost at about 8 pounds of boost I was near about 75 pounds of fuel pressure at redline to be in the neighborhood of 12.0:1 AFR

I personally would stick to a 1 bar map for your computer, I'm not aware of anyone here that has gone to that extreme... I'm an engineer and I didn't even want to bother with it....

I'm not sure of the program you are using to burn your chips, or how you are reading the Eprom so I can't be exact in your program.. however in the LT 1 edit I had to change the MAF curve... I as I said left the injector voltage settings alone and just compensated with the onboard fuel system settings witha 2 bar MAP... The timing settings were simply the ignition timing settings... I kept them fro the most part stock and I had to pull out timing near the full throttle range where i was seeing knock retard ... I did play a bit with the fuel enrichment to handle the throttle crispness.

Hopefully this will help you in the right direction... If you don't have logging software... it is a must to do it right or a lot of cash and a dyno... also make sure you have a fuel pressure guage and a boost guage.... Other wise you are totally doing this in the blind and it could cost you your engine... Once you have the car running I did incremental tests 25 % 33% 50% and up watching the knock retard settings to be sure I wasnt grenading the engine ... only till I had the lower throttle settings and fuel issues under control did I even attempt to go WOT...

Everyone here that i know in the forum are eager to help... they as I just want to be sure that they are clear as to what the questions are, so they can give you specific answers. We understand you aren't looking for exact numbers etc. but as they say especially in programming and adding a supercharger to your engine can be handled in a multitude of ways...

hopefully this will help you in the right direction...

Mo


[Modified by Mo_Bandy, 2:45 AM 5/8/2003]

 

As I said I don't know your ECM, but usually injectors are usually just a constant or fuel injector offset chart. Usually injectors have non linear flow rate so you will have to adjust your VE vs map table. It sounds like you have no tuning experience. IMO buy a scan tool and start tuning your motor that doens't have a blower on it. Get you feet wet and then your be better prepared for a harder challenge (blower) It will be a lot harder to tune and learn it later when you have already add the blower. I told you above basically what is need to add a 2 bar map. You will probably also want to find commented source code to see if any of the constants are modified by the map signal.

"You can recalbrate your fuel curve to squeeze the map table down however if you look around your ECM parameter (and if you have dissambly of the source code) you will notice a lot of calculations are based on the map (load) value, so everything is thrown out of whack (EGR, Torque converter lock up, timing table, etc.) A good portion of your ECM function will need to be scaled, this is a big time job."