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"Custom" Chips - Just Say No!

2K views 6 replies 5 participants last post by  edge 
#1 ·
As many may already know, I converted my 94' Suburban to a TPI using the Speed-Density TPI system off of my 1991 Firebird GTA. Both vehicles are stock 5.7L engines. Click here to see the swap itself. This information is specifically for OBD-I ECMs.

The "Custom" chip I bought from Street & Performance was anything but "Custom". "Custom" is a joke! My $200 custom chip was nothing more than a stock Z28 AUJP bin; but had some minor changes to the VE tables, Spark Advance Tables, EGR and Fan-on temperature. A stock MEMCAL is like $80 at a GM dealer, and you can probably find them for $30-$40 on the internet.

For the price of some "custom" chips, you can invest in the equipment and software to read, change, and burn you own chips. By using a "flash" chip conversion like I did; it is easy, quick and can be done as many times as needed to customize the chip for your specific application. You can make changes and field verify how the engine and vehicle respond using real-time datalogging.

It is not as hard as you might think. Click here to see how I did it. Be sure to read the link to the article titled "Chips Know it All". It is the best summary I have come across when researching this topic.

Good luck with your "custom" chip tuning, Ed www.edgesz28.com


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#4 ·
Any type of custom chip you buy from ANYONE isn't really custom. In order for it to be custom, they'd have to come out and tune the chip at your vehicle as they datalog it. Without the information of how the car is actually running (in the form of fuel tables, spark tables etc.) there is no way they can give you an accurate chip burn to optimize your vehicle.
 
#6 · (Edited)
Here what I am talking about

WakBordr7387 said:
Are you talking about those little peice of crap chips that are about 20 bucks that you can find all over ebay? Those little things are worthless, my friend bought one and his car wouldnt idle right and flooded. He was pretty mad and just threw it away. Brad
Not sure what chips your friend had. Here is what I am talking about:

Original GTA MEMCAL (blue unit), flash chip-64kb (front) & HDR1 (left). The flash chip shown costs like $5 each:


Reading the stock EPROM using the HDR1 and BURN1: The small chip is the stock ERPOM and the stuff on the left contains limp-home information as well as some other spark related stuff that you cannot change.


Flash chip in the BURN1. Note - with 64kb, you can actually "stack" multiple bins on one chip. Moates sells an adapter that has a switch. If you are using a MAF bin, you can actually stack as many as 4 different bins on one chip. The Speed-Density bins are 32kb, so only two can fit. You could burn one bin for everyday driving, and one for the weekend (i.e. more aggressive spark and fuel configurations).


GP1 adapter in my 727 ECM. The original MEMCAL is inside with the blue cover off. The GP1 adapter has a little release lever for quickly changing the flash chip. Once I get my tune right, I will install a G1 adapter which excludes the lever.


Here is the parts list:

I decided to go the "flash" chip method, so I purchased* the following items from www.moates.net:

CABL1 OBD1-Style ALDL Connector [Model: CABL1] - $30.00 (* Note - I used the cable from my Auto-X-Ray)
ALDU1 USB-to-ALDL Converter [Model: ALDU1] - $50.00
BURN1 [Model: BURN1] - $85.00
GP1 Package: GM Adapter with 2 chips [Model: GP1] - $55.00
HDR1 Memcal Header [Model: HDR1] - $10.00

EDIT Note: You only need the CABL1 and ALDU1 pieces for datalogging and emulation.

TunerPro (free) or TunerPro RT (free, but $30 to register). This program allows you to read, edit and burn flash chips using the BURN1. The RT version allows for datalogging and emulation.

ECU Editor to use with TunerPro - Super_8dm2 (free)

TunerPro RT has datalogging abilities. If you get Moates' Ostrich, you can emulate which is live datalogging and making changes "on-the-fly". I do not really have a need for that with my stock application.

As far as I am concerned, DIY PROM on the OBD-I ECM is about as easy and straightforward as responding to this post. Two months ago, I would have never thought it was this easy.

Ed
 
#7 ·
Siggy_Freud said:
Any type of custom chip you buy from ANYONE isn't really custom. In order for it to be custom, they'd have to come out and tune the chip at your vehicle as they datalog it. Without the information of how the car is actually running (in the form of fuel tables, spark tables etc.) there is no way they can give you an accurate chip burn to optimize your vehicle.
Siggy is dead-on with that assessment. Here is a perfect example:

If you have a stock TPI 5.7L with 22 lb. injectors, they should be set at 43.5 psi without vacuum (stock non-adjustable regulator). Your stock EPROM or bin will have the "Injector Constant" set at 22. If the constant is set at 22 and you bump up your fuel pressure with an adjustable regulator to say 50 psi using the stock 22 lb injectors, you have effectively installed 23.6 lb injectors. Without changing your constant to 23.6, your system will run rich and there will be nothing you can do to change it without having the ability to read, change and burn a new chip. So without having the ability to change the constant, there is no reason to change the pressure (IMO).

It gets really bad when someone installs 24 lb Ford SVO injectors (these are very popular with TPI guys) and do not change the stock 43.5 psi fuel pressure. This is like actually installing a 25.3 lb injector, because Ford's SVO injector is only rated at 39 psi.

The holds true for setting idle RPM and the spark and fuel tables. Right now, with a basically stock chip, I am running lean at idle, about 50% correct at part-throttle (some lean, some rich), while cruise and WOT are about right. I still have some spark to take out in the part-throttle range. But by doing my own chips, I can make small changes to see the effect (whether positive or negative). I figure just tuning my stock Suburban engine will take probably about 20-30 burns. Right now I am at about 5. I have heard of guys doing the high-performance stuff making up to 500 burns before optimizing their setup.

Ed
 
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