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I have a 1994 GMC K1500 in which I have installed a new 383 stroker. Runs great and has lots of power but I keep hearing something about doing something about the computer (ECM?) fixed and that it should be re-flashed or something? Computer idiot here so my terminology probably aint right and I may not understand what you're talking about.
1987-1995 TBI computers are On Board Diagnostics ONE or OBD1. The OBD1 TBI computers use removable Chips.
This gearhead-efi link has chip information for the 1994 GMC K1500: http://www.gearhead-efi.com/Fuel-Inj...er-form-Moates
The original stock 1994 GMC K1500 chip WILL NOT provide OPTIMAL performance for a 383.
Is the 1994 GMC K1500 still using the original stock chip?
dave w
yes it isQuote:
Originally Posted by dave w
So where do I get a new chip? and how much? I know nothing about this.
Actually with the original 150,000 mile stock motor I had a Fastchip that helped at WOT. Fastchip said I shouldn't use that chip with a 383 and wanted about $350 to make me a new one, that reasonable?
Ok, it's good to know the original stock chip is being used.
Myself and several other gearhead-efi members have been at the same crossroad, wanting optimal performance for our modified TBI engine.
There are options to achieve optimal TBI performance. Myself and several other gearhead-efi member decided pursuing the "Do-it-Yourself method. Myself and other gearhead-efi members realized the learning curve would be steep to get the optimal performance we knew the engine modifications are capable of.
Myself and other gearhead-efi members learned a TBI Performance Chip is "Tuned" with "FEEDBACK" information using TunerPro RT software on a laptop. TunerPro RT will record engine performance information so the following questions can be answered:
Is the chip running lean?
Is the chip running rich?
Is there enough spark advance"
Is there to much spark advance?
I've successfully tuned dozens of TBI engines using TunerPro RT.
It could be a harsh reality, a Plug-n-Play TBI performance chip will be chasing after the taillights of a "Tuned" TBI Performance Chip.
Seek a "Tuner", not a Plug-n-Play TBI performance chip. A TBI "Tuner" will use TunerPro RT data logs. If your willing to do the TunerPro RT "laptop thing", optimal TBI performance is achievable.
dave w
So, I download TunerPro RT from somewhere and buy an adaptor cord from somewhere, hook one end to the truck and hook the other end to my computer? Does this allow you to reprogram the truck computer from your laptop computer? Sounds scary for one who has had a driver's license since 1960. According to some local buddies, the Service Engine light comes on once in a while because the computer doesn't know its a 350 anymore?
All good questions. At first I looked for a good overview forum thread to point you to, but didn't find one in my quick search of this site.
I'll briefly answer you last questions, then provide a better source of many more answers.
The ALDL cable doesn't not allow you to reprogram the ECM (aka ECU aka computer). It simply lets you observe and record/datalog what the ECM is seeing and doing as it controls the engine. It can give you an idea of what and where your modified engine isn't getting the correct fueling it needs. One end goes to the ALDL port under the dash on the driver's side, other end goes to your laptop. TunerPro RT accesses the data that the ECM is broadcasting to that connection point on the truck. Regarding the truck's check engine light, yes, it is certainly possible that the truck will illuminate the light due to the modified engine. There's a number of diagnostics in the ECM that are constantly evaluating if the engine and its sensors are running correctly. If they aren't it will illuminate the light. Several of the benefits to tuning the ECM is that you can 1. make the engine run correctly, 2. Modify diagnostic parameters to work with the modified engine while still serving their purpose 3. Disable diagnostics that may no longer be relevant to your configuration (ex: EGR removal).
I'd recommend downloading this book and reading it as a first step:
gearhead-efi.com/gearhead-efi/doc/CustomEFIS%20EFI%20Setup%20Manual.zip
It not only goes into the why's at both a high and detailed level, but also the how. Since the book was last updated, there have been many advances in the "how" with respect to the actual tuning and reprogramming process (real time emulation like the Ostrich line of products), but it will give you a much better fundamental understanding of what the tuning will accomplish.
Once you've read through it, this forum is a great place to ask questions to fill in your understanding of places where the book might not make sense as well as get specific suggestions around your particular engine and truck.
Hope this helps!