Hello everyone

I have been reading over the sticky's in this section and have decided this board is the appropriate one to bring my project to considering the vast knowledge of the board members on diy prom. I'll start off by introducing myself and my car. My name is Max, and I live in the Buffalo region of Western New York. My car is a 93 Firebird with the 3.4 v6. Some of you may know that the PCM that came in these cars were sort of a mix between obd1 and obd 2 (from 93-95) and there is little to no tuning available since it is a "flash only" PCM and noone really wants to hack it. Aside from using a stand alone system that is like Megasquirt which I think can get a bit too involved. A fellow from South Florida ( I think he is a member on this board but i'm not sure) has created a tuning solution for me. He's taken a PCM from a 91 Lumina (7727 IIRC) and repinned it so that it will plug into my current PCM harness and run the car as is. The only difference is that now i can tune it because the 7727 pcm has the removable prom chip that can be tuned.

I'm not just tuning for no reason. In fact, as of right now my car won't even drive. I've got many things done to the car. Practically all bolt ons imaginable plus P&P head work and a ridiculously radical custom camshaft from Comp. Add in bigger injectors (19lb as opposed to the stock 17) and you can start to see why my PCM is NOT happy right now. The car will fire right up and idle but it will stall out if i try to drive. The vacuum is so low right now that the MAP sensor is throwing a code even though it is working perfectly fine. I digress...

I'm relatively new (actually completely new) to tuning, though i've been reading up on this site and others. I went ahead and bought all the equipment i will need for tuning/datalogging such as the burn 2, usb datalogging cable etc. I will be data logging with tuner pro rt and burning with moates "flash and burn" software. The only thing i will need help on ( i hope ) will be my tables. This is where you guys come in. If i datalog and put up some info, i'm hoping you will all be willing to help me with my project, or at least give me advice and push me in the right direction. Not MANY people have done this exact pcm swap with this particular car but i've been reading up on tuning with chips and it doesn't look TOO hard.

So can i count on you guys to help me out?

Here's some pics to wrap up my first post.

the car:DSCF4397.jpg?t=1256347067

the tuning equipment:

DSCF4410.jpg?t=1256347119

the engine:

DSCF4267.jpg?t=1256347225

the radical camshaft:

 

i may not be a huge help to you, but i can atleast find the other guys thread for you.


https://www.thirdgen.org/forums/diy-...i-7727-qs.html



the repin looks like a nightmare. i'm guessing the pins are different from one ecm to the other. me and a friend just did a 93 lt1 z28 repin to a 727 ecm and it wasn't bad at all since the pins were they same type. just unplug and replug where they needed to be.


what code are you planing to run? i saw in his thread that he went with $A1. which i do believe has a wideband patch out there somewhere.(you might want to look into a wideband as well) so that would be good to find. that and a xdf with as much definded as you can. since its so far from a stock setup, a lot might need to be changed to get it running great.

i think he went with A1 because its a DIS code, but $8D can also be made to run DIS and 6cyl(i'm 99% sure). the S_AUJP (which is $8D) has been worked over and added lots of useful stuff. like VE tables and timing tables extended to higher rpms, which may be helpful for your v6. if it turns a lot of rpms. ofcourse $A1 may have this too, i haven't check that code out much.


just random ideas tossed out. good luck with the repin and pretty much everything you need is around here somewhere. just finding it might get you headaches from time to time. i know it has me haha.

 

haha yup that's the guy who is doing the repin for me ^^

he ended up using the $a1 and got a solid "base tune" for the 3.4 since he had one at his shop that he was working on. He saved the tune and will be sending it along with the computer so all i have to do is verify that the pcm will run the car OK as is (make sure no wires were mixed up), save the .bin that he created, then datalog and modify that tune for my particular setup. Then i'll just burn a chip and hope for the best!

Like i said, i might need you guys to help me out with the data changing etc.

For instance, I've got a 180* thermostat in the car and i want the radiator fan to come on at about 195 and go off at about 183. Which boxes need to be changed for this to happen?

Another example: I've got 19lb injectors, how do i modify the fuel tables to get the proper rate of fuel flow?

questions like this ^ is what i'm sure i'll be having, but all the other stuff i should be solid on aka data logging and chip burning.

thx for the reply

Max

 

I highly recommend that you use the $8D mask. Not only is it performance based code, it is also a lot better known then the $A1 mask. Which means that not only will your questions be more readily and easily answered. Your engine will run better.

RBob.

 

thanks RBob, but i believe the guy who made the new 3.4 .bin said he tried to use the $8d mask but it wouldn't account for the *59 offset in cylinders ( i don't know what that means.) So he had to go with the $a1.

I'm told it won't be that big of an issue...

 

he was talking about the reference angle of the crank trigger wheel for the DIS. its been talked about on here for a while and figured out. its really the max advance and max retard values that are the hard part, but anyways... the starter bin he's sending you will be nice and help alot to get a feel for tuning.

once you get deep into turning, you can look into changing codes if you want to.

for now, little things like fan turn on temps are slightly different names in every xdf file. but it will be something like fan enable temp. and fan disable temp. you will see it. just set it to what you want, save it and burn it to your chip.

 

I ran my 3.4 MPFI with DIS on a 4.3 V6 TBI PCM in my Blazer. So the V6 DIS thing has been figured out. Its really like they said a Max/Min Advance/Retard setting thing. I cannot remember exactly how I did it, but I used a timing light to figure out how to do it. I think I had to put in a distributor setting of +60 degrees then adjust it to allow for 70* retard and -20* advance. That gave it the normal 50* window (10* retard, 40* advance)

 

cool, well I don't think i'm going to have to change too much on the .bin It's not like i'm super charging it. Just accounting for a bigger cam/injectors plus some other minor stuff, but thats more me hoping than anything.

I don't see why one .bin would be better than another (maybe someone can enlighten me?)

i've been told the $a1 has been fully hacked and since i'm being sent a version of the $a1 thats already been modified for the 3.4 engine it's not like i'm starting from scratch.

Let me get some datalogging in (actually need to have the PCM shipped to me still.... ) and then we can see where it's at and go from there. From what i've been reading it looks like fuel is the first issue to tackle before moving on to anything else but i'm sure as hell my VE is totally jacked right now and is the biggest issue affecting my driveability.

I'm a total noob so don't feel bad to correct me if i say something very stupid

thanks

Max

 

so how would i go about tuning for bigger injectors with the $a1 .bin?

the stock 3.4 is set up for 17lb injectors and i have 19. Is there something simple to change that will make the fuel changes across the board or will i have to datalog first, see how rich i'm running and then just scale back wherever i have to to get my fuel ratio correct?

 

i've never looked thru the A1 xdf file, but yes, there should be an injector constant somewhere in it. i don't know what formula it will use. some are in grams per hr some are straight foward lbs hr.

 

funny you should mention that. i was just looking over the BPC formula over in the TBI "come in for a free tune" thread. Doesn't look that difficult. with that formula i should be able to set the bpc for my 19 lb injectors based on my engine size and my set fuel pressure (easy since i have an adj. holley fuel pressure regulator)

that is, if its the correct forumla for me to use lol.

thx for the reply.

 

looks like i found my bpc using this formula:

I think A1$ is 16.7lb/hr. Opening BFUZ bin shows 224 for the BPW vs EGR at 0% EGR.
So for 19lb/hr injectors we take old injectors/new (16.7/19 *224) = new constant for 3.1L with 19lb/hr injectors. 196.88421 ... Now to adjust for larger displacement.

3.1L is 3136cc, 3.4 is 3350cc (have to use actual CC to be accurate). This time take new displacement, divided by old, times constant. (3350/3135*196.88421)=210 BPC. In TunerPro RT you can apply your adjusted value across the whole EGR table in case you want to enable EGR.


210 @ 43.5 psi but if i change the psi the bpc will change as well.