larger injectors adjust afm to match?

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larger injectors adjust afm to match?

Postby outinnowhere3193 » Sat Oct 25, 2014 2:31 am

I was curious....I'm still fairly new to everything with the alltrac. Anyways when putting my engine in.....(bought in pieces) I noticed I was missing parts and along those parts was a AFM. So I pulled one off a NA car and it seemed to work. Well when I got the car together to drive it I learned it was supper rich. So I learned how to adjust the AFM flapper spring and made a 5 click adjustment and now the car runs good.

Question is for someone like me who isn't worried about making maximum hp and wants a little more power on a budget. Could I upgrade my injectors and in turn up my spring pressure once again? Of course I know the AFM adjust timing as well so would end up with say what the ecm thinks is 5 psi is really 10 or 15.

I know there's several variables. Just wondering if anyone was familiar with the timing map and fuel map enough to say oem is conservative enough with a wideband to adjust it you would have possible some lean and rich area's but within tolerance.

I just love exploring and learning and thought I'd give you guys something to think about and discuss rather it's possible.
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Re: larger injectors adjust afm to match?

Postby klue » Sat Oct 25, 2014 3:01 pm

Hey!

The AFM based fueling as you said also targets timing cells within the map. The fuel ratio could be 10.5:1 or it could be 16:1 and you can not tell the difference. So you might have the fueling on spot, but the timing will not be. The 3s engine like many engines will accept a WIDE range of fueling AFRs and "run good". but only under a specific range will it run safely, this range is not perceivable. It is calculated with the proper metering equipment and experience of EMS tuning. If there is reason for you to put larger injectors on you should just upgrade to the gen3 MAP electronic metering system, or get a affordable EMS and explore tuning options.

Years ago when I was figuring things out and how far I could push the engine I did stuff like what your doing. It was great learning experience and I did a lot of stuff that was unique. I also blew up a lot of engines. So take it how you like :lol: :lol:

cheers
Luke
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Re: larger injectors adjust afm to match?

Postby outinnowhere3193 » Sat Oct 25, 2014 5:30 pm

Luke I completely understand what you are saying. For fuel I'm running a wide band so I'll know if I'm lean or rich. But it's the timing map I'm not sure about. The real question is....is the factory timing aggressive or not. If it's very conservative then the extra advance would be a benefit.....heck if I had the timing map I could simply retard the base timing. It's very possible but the return n retarded timing and possibly rich areas could be not worth the top end gain.
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