Injector Constant

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Nov 15, 2004 | 12:47 PM

Muffin

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From: Merritt Ils Fl

Injector Constant

I have always said there was no such thing as a dumb question but this one may come close: What is the injector constant and where do I find it. Flow rate, ie. lbs/hr? I upgraded from a 870 to a 165 ECM. Bmbl BE runs better than ever but do I need to do anything with injector constants since I am using 85 injectors with an 89 ECM ($6E) and the ARAP bin.? Have not done any datalogging yet, daughter is holding my laptop for ransom.

Nov 15, 2004 | 01:01 PM

gbody5

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From: Stuck in the 80's

I would just check your BLM's and see if you are rich or lean, only then will you know if you need to change the constant. Are the injectors originals?

Nov 15, 2004 | 03:48 PM

Muffin

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From: Merritt Ils Fl

Originals. I was wondering what it was and where it came from.

Nov 15, 2004 | 04:35 PM

gbody5

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From: Stuck in the 80's

It is how much fuel the injector flows at a specified fuel pressure, the constant is used in the chip definition to tell the ECM how long to pulse the injector. Ex. In my 88 the stock .bin has the injector constant at 20, when I went to higher flowing injectors (24 lb/hr) the car ran rich until I increased the constant value. This told the ECM that I have larger injectors and to reduce the Base Pulse Width (BPW) of the injector, hence reducing the amount of fuel in the A/F mixture.

Nov 15, 2004 | 09:38 PM

Muffin

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From: Merritt Ils Fl

Thanks gbody. Now I wonder if the value in the stock ARAP bin. is much different than what the stock 85 injectors do. I guess my first scan will tell me as you suggested.

Nov 15, 2004 | 09:45 PM

gbody5

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From: Stuck in the 80's

The ARAP bin I have shows the constant as 21. As far as I know that is the size for all L98's / 350 TPI stock.

Nov 16, 2004 | 10:47 AM

Muffin

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From: Merritt Ils Fl

Thanks, thats one less thing I have to worry about.

Nov 16, 2004 | 11:04 AM

tjwong

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From: Portland Oregon

Quote:

Originally Posted by Muffin

If you are using TunerCat, open the file then click on the ECM tables menu then on constants. It is there that you will find the injector size constant. Once you get your Laptop back from your daughter, scan it to see where your fuel trims are and go from there. I can't remember but I think that the 85 and 89 injectors are either the same size or very close to one another.