I just upgraded my fuel injectors from stock (28 lb/hr) to a set of Red Stripes (38 lb/hr). After installing the injectors, I burned a new chip that sets the fuel injector constant from 281 msec/gram (28.2 lb/hr) to 234 msec/gram (about 34 lb/hr). When that didn't work, I tried 210 msec/gram (about 38 lb/hr). In both cases, the car did not want to start. It looked like there was a ton of fuel shooting through the engine - vapor coming out of the breathers and thick black smoke coming out of the tailpipes.
Is there something I'm missing here? Is there something else in the chip that has to be changed? Some other problem?
I want to go to racing on Saturday, but I can't if I can't get the car started!
TIA
Two things to think about:
Is the chip you're changing from a vendor which uses anti-tamper code?
Did you re-calculate and enter the new checksum?
Those are good points, Dave. Here's what I know...
The code that I was using last night when I had problems may have anti-tamper code. I'm not 100% sure of the chip's original origins, but I've made several modifications to the code in the past without problems (spark, fuel cut-offs, etc.). However, this is the first time I've changed fueling stuff.
Instead of recalculating the new checksum, I changed bit "7A2" to "AA", which instructs the computer to not do a checksum check. IF ANYBODY KNOWS THE PROPER WAY TO CALCULATE THE NEW CHECKSUM, I WOULD BE MOST APPRECIATIVE FOR YOUR GUIDANCE.
Tonight when I got home from work, I made a chip that consisted of the stock 1986 code. I modified only the fuel injector constant to "35" (about 38 lbs/hr) and changed the checksum bit to "AA". I put the chip in the car, and it fired right up! After I got the car warmed-up, I grabbed the same chip that I used last night. It worked just fine - the car started right up and ran fine.
Best I can figure, either the new injectors never got primed properly last night, or my chip doesn't handle cold-starts very well. I'll find out when I fire her up tomorrow, I guess.
Thanks for you thoughts,