91 L body, 3400 and 5 speed swap

[91BerettaGT]

Alright here's what it comes down to... and I'm slowly learning here. Just registered GMPCM and found it the easiest to use so far... and it does have a graph if you can find it...

Chris88CL is getting me a chip with the socket in there so I can swap some chips in and out so that I can modify my car for most power...

I have a 1991 Chevrolet Beretta with now a 3400 engine and I also swapped the 5 speed into it. The factory BCC was AUXW. I lost the chip and bought a new one came as BFAU (replacement i guess) that was for the 3 speed Auto.

"In Depth Computer" has drastically changed and I can't get to the .bin file's that used to exist as links from the pages provided.

I know that PE is called Power Enrichment and that would be obviously when WOT is achieved. and I wanted to know how to tune that properly.

So far I've figured out how to turn the SES light off for several codes like A/C for the reason that mine doesn't exist anymore. I've figured out how to remove speed and revv limitors (well I adjusted them just about 5 mph more on speed and revv up a little more for obvious 3400 reasons)

I also wanted to know if adjusting the Air Fuel ratio's vs the RPM would increase fuel... for example I believe around 4000 rpms the air fuel ratio read 12.5:1 but 4500 read at 11.7:1 I wanted to know if increasing 4500's to 12.5:1 or even as high as 14 (what i've heard is optimum performance) would allow me to gain power.

I figured out that you can somehow adjust the size of the engine in there but I only found it once and Can't find it again, I adjusted it from 191 to 207 Cubic Inches. and I also burnt several chips, one I named MAP Mods, I think I adjusted something to do with the Map Sensor there...

Every search I come up with someone is talking about something different from computer tuning, or atleast if it's on topic, nothing to do with what i'm searching for... Any and All help is appreciated! Sorry for the long post...

[TheProfessor]

so what is the problem you are having
i think you lost me

[91BerettaGT]

so what is the problem you are having
i think you lost me

Ya know, I think I lost myself... Basically I want to tune my 3400 for performance, the engine's running lean due to the 3.1 injectors on the 3400's block and the different flow patterns... what do I need to do in GMPCM in order to increase power... ?

Some of the stuff they have labled in there doesn't mean anything to me, until I read the FAQ on the main site "PE" meant the same as dirt to me...

[Mechanic]

You would first want to ensure that your idle and cruise fueling are within reason. There are several areas that you can use to approach this within the A1 code :

1) BPW VS DESIRED EGR
The value at 0% EGR is the important one here as this is what we refer to as the Base Pulse Constant. Raise or lower this value until you obtain a BLM of 128 on your scanner. In the case of an engine that is slightly larger than that designed for the PCM code this is the recommended area to change for idle fueling (idle fuel is BLM Cell 0). Note that this adjustment is quite sensitive, so you need to take care to make a few extremely small changes rather than just one large change. If you have not disabled the EGR function, you will need to apply a factor to the entire table rather than just changing the 0% value. EGR is a variable best left out of the equation until you have optimized your fueling. Setting the constant labeled "IF COOLANT <= THIS DISABLE EGR" in the EGR section to "FF" hex will disable EGR function.

2) INJECTOR FLOW RATES
The two constants, single and double fire provide a much broader adjustment of BPC over the entire spectrum of operation, generally if your injector flow is pretty close to stock you would go with #1 for idle fuel. The fuel injector constants are most useful in tweaking cruise and part throttle fueling (BLM Cell 1).

3. FUEL INJECTOR OFFSET VS BAT
This is a very coarse adjustment, but has its value when the injector flow is so low at idle, that the injectors minimum operational pulse width is blocking further adjustment of the BPC. Comes in handy when using much larger injectors than stock, which is mostly applicable to forced induction applications.

4. VE Fuel Tables
The VE tables are of particular importance when the linearity of the fueling curve has changed dramatically. By incorrect linearity, I mean that the slope of the fueling calibration curves no longer reflects the fuel demands of the engine over the entire spectrum of operation, and this can be caused by many factors. Head porting to increase upper RPM VE is a good example, and in a case like this, a simple increase in BPC in attempt to recalibrate part throttle fueling will have a direct counter result appear as a rich idle due to fact that the "slope" of the curve is no longer correct. In the case of head porting, we can leave the lower RPM and low load areas alone, and just adjust the areas where increased VE has occured from the modification, reshaping the curve.
Three dimensional tables can be a bit confusing, but just remember that MAP is a measurement of the load placed upon the motor. The fueling demand at a specific RPM going up a hill will be quite different then that required when cruising at this same RPM value.

The VE tables provide a very fine adjustment at nearly any area of operation, but a primary goal would be to adjust so that idle, cruise, and part throttle fueling have the same BLM values. This is called restoring the curves linearity or slope correction. A factor applied to the entire table would have about the same result as adjusting the BPC. There are upper limits to the VE table adjustments, and that is another area where BPC adjustment can be important.

Once you have the fueling in check for idle, cruise, and partial throttle operation, you would move to Power Enrichment fueling.
PE mode can more easily be understood if one relates it to the secondary on a carb. It kicks in at a defined throttle angle (% TPS) just like a secondary plate does. PE fueling is adjusted by modifying the "PE A/F RATIO" table, located in the FUEL PE section. The drawback here is that one cannot use the scanners BLM values to optimize PE fuel. Without a wide band oxygen sensor setup, your best bet here is to adjust until you remove all evidence of knock counts. The threshold just before knock counts are detected is typically the sweet spot, but quite hard to get exact without the higher-level tools.

The reason we approach this in such a manner, adjusting idle, cruise, and part throttle before we adjust PE fueling, is that the last relevant BLM value before PE mode entry (if not indicative of a lean condition) will be used to skew the PE fueling curve which can easily cause a reduction in performance.

[Quintin66]

..................WOW......................., I think I actually understood all that. but I wouldn't have the foggiest how to any of it.

[SappySE107]

Definetly use larger injectors. THe computer can't compensate for what the injectors can't flow, and the 3.1 injectors certainly wont flow what you want for max performance. Once you do that, follow what mick said, though the battery offset may be a bit much for you to play with at the moment. I only changed them on my 3.1 when I put the mustang injectors in because I found the values for the ford injectors.

Don't worry about the AF ratios and thinking whatever AF is supposed to make more power...cause its not the actual AF ratio. You can either change it or the VE tables and come up with the same results at high RPM (past 4000, mostly 4800+ unless you drive it way different than normal). The AF ratios in the PE table are for fuel calculations, but you need a wideband O2 or EGT to know for sure whats going on. A dyno is the only way to get peak performance from the motor.

Can you send me that chip .bin for BFAU? I don't think I have it. I know the site needs to be redone, but the files are gonna be uploaded for the downloads section with descriptions. I have a program that tells me what the chip codes are for each year/make but I doubt ill have it really up and running till winter hits solid and I have nothing better to do. If you want a different chip code, let me know and I can send it to you. In fact, they are all on the site still but brad copied the text over but not as HTML...so all my links were lost.

Mick, do you mind if I use that on the site when I start updating the chip tuning section again?

[SappySE107]

updated that page with the link to get the files.

http://60degreev6.com/bins/

[Mechanic]

Mick, do you mind if I use that on the site when I start updating the chip tuning section again?

As always, that would be fine with me. I know that my previous reply was likely a bit more in depth than asked for, but its usually better to go into such detail rather than risk any misunderstanding due to more vague answers.

Its likely that it would also seem a bit confusing if you did not have the GMPCM software at hand so you could follow along.
Basic fueling optimizations such as these will be performed automatically once our new software, AIVMS, has be completed. But, AIVMS does have some additional hardware requirements, so the manual tuning concepts will still be quite important.

[91BerettaGT]

Actually... alot of it made sense,... still confused how to do it...

Anyone want to make any money?...