Too Big?
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Elder User
Joined: Mar 2002
Posts: 950
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From: Conroe, TX
Too Big?
If money was not a problem, and all other parts of the efi system were strong enough, is there a such thing as too big of a fuel injector on a stock engine. this is talking about the flow rate of the injector. This post is to hopefully end a two week argument
thanks,
Chris
thanks,
Chris
Moderator
Joined: Jan 2001
Posts: 56,995
Likes: 2,741
From: Virginia
Too Big?
Yes, this can be a problem on high output engines which need the extra large injectors. The problem surfaces at idle and low fuel consumption modes such as cruising. The computer controls the amount of fuel in the engine by turning the injector on for a certain period of time and then off. The larger the injector, the more fuel it will flow when open. So the computer has to turn the large injector on for a very short period of time to try to keep the amount of fuel the same as a smaller injector which will be able to stay on longer. These very short bursts of fuel from the large injector do not have a very good spray pattern, and the amount of fuel sprayed is harder to control. This will affect idle quality and fuel consumption.
Senior User
Joined: Feb 2002
Posts: 347
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From: ct
Too Big?
absolutely correct. this on time is called pulse width. this pulse can only be adjusted down so much. if an injector is too large it will dump too much fuel and affect idle quality and so on. also some higher performance injectors usually over 50# are low impedence. these can not be driven by the stock eec. they need a separate injector driver to run them. it gets complicated.
