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Old 01-15-2001, 09:41 PM
Richard Wooldridge Richard Wooldridge is offline
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Join Date: Dec 2000
Location: Battle Ground, WA
Posts: 576
Throttle Body Injection...

Hi Donald,
It sounds easy because it really IS easy! One of the outfits that already does this type of thing is Howell EFI, they sell Throttle Body injection and Port injection setups to fit most anything. They all use a GM Electronic Control module with the chip programmed for the basic cubic inch displacement of the engine it's being used on. As I said in the previous post, the ECM is capable of fine tuning itself to match the requirements of the engine, so if things aren't perfect at first, they will be after a week or so of driving. One item I forgot to mention on the throttle body itself is the idle control. The butterflys close completely on TBI, and there is an air bypass that is controlled by a stepper motor. The stepper motor is adjusted by the ECM to make the engine idle at around 1000 rpm when cold, tapering down to around 650 when warm. The ECM has an input for the A/C compressor, and when the A/C compressor is switched on, the ECM immediately opens the stepper motor a bit so the idle speed is maintained. TBI takes all the difficulty out of making an engine run properly, hot or cold. It provides immediate starts at all temperatures, and the fuel pressure, while not too high at 13 psi, is still high enough so there are no vapor lock worries. I think I really will put it on my Jag, as it would eliminate the twice yearly problem of making the very difficult chokes work properly on MY 175's.
Regards, Richard Wooldridge
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