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Alan L Alan L is offline
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Join Date: Apr 2006
Location: New Zealand
Posts: 3,261
The injectors definitely do deteriorate in performance over time. (I am not a professional injector service guy - just someone who has spent some time fiddling with them on my various CIS Porsches). The two common problems are fouling with fuel deposit (cleaning them can help this - the best claims to improvement I have seen posted is the ultrasonic process). And over time the heat damages the internal springs which cause the pintel (nozzle) to resonate at very high frequency. In either case, you will get a deterioration in fuel pattern. The other thing to monitor (usually while testing pattern) is the opening pressure - there is a specified range. But whenever I have seen poor injectors the spray pattern is quite obvious - it shoots out to one side or parts of - rather than a nice 360 deg cone.
I suspect many of the stubborn tuning problems (hesitation under light throttle etc) are due to imperfect fuel flow (rates or pattern) at the injector.
Alan
Old 04-12-2008, 12:37 PM
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