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The Terminator
Engine/Tuning
Self Tuning With SCT Pro Racer
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<blockquote data-quote="03cobra#2" data-source="post: 16459857" data-attributes="member: 52057"><p>I wanted to add a bit more. As I make my way through the various parameters I turned my attention to injector timing and did a few hours of research on the subject. </p><p></p><p>Injector timing: When you have stock cams, and are degreed stock (no overlap) you can keep everything is SCT set to 0. The parameter is injector timing vs ECT. This parameter dictates when the injector fires in relation to TDC (stock is set to fire exactly at TDC). When you have aftermarket cams with overlap this is when you may want to adjust this parameter. There are a couple schools of thought as far as having the injector fire before TDC or after TDC. One thought is you want to fire the injector before TDC (or slightly before the intake valve opens) so you are firing the injector on a closed intake valve. The thought is that if you fire the fuel on the hot closed valve is aids in fuel atomazation (this could hurt cold engine drive-ability). The potential problem comes in when you have a more aggressive cam with valve overlap (with overlap the intake and exhaust valve will be open at the same time for a certain period of time). If you are firing the injector before the exhaust valve fully closes you are flushing fuel out of the exhaust (hence why you may get a strong fuel smell from the exhaust when the car is sitting at idle). So the other school of thought is to delay the injector firing so that it fires after the exhaust valve is closed. So, while the injector won't be firing and fuel hitting the intake valve at just the right time at least there won't be fuel going out the exhaust.</p><p></p><p>This is one of those parameters that you need to play with. I don't think there is really a right or wrong answer...but adjusting this could help smooth out drive-ability. What you need to do is plug your cam specs into a calculator (duration, center-line, lsa, ect) and see exactly where your intake valve is opening and where your exhaust valve closes in relation to TDC. In my case I degreed my cams to Comps specs and don't have a lot of overlap. Then change the parameter in PRP. If you enter a negative value that makes the injector fire earlier (before TDC). If you enter a positive value it delays the injector firing (after TDC). According to my calculations and how I degreed my cams my exhaust valve is fully closed around 5* after TDC so I put 8* in PRP for my injector to fire a couple degrees after the exhaust valve is closed and go from there. </p><p></p><p>I just wanted to touch on this as there are a few threads here and there. I'm not an expert on this but I believe this is the basics.</p></blockquote><p></p>
[QUOTE="03cobra#2, post: 16459857, member: 52057"] I wanted to add a bit more. As I make my way through the various parameters I turned my attention to injector timing and did a few hours of research on the subject. Injector timing: When you have stock cams, and are degreed stock (no overlap) you can keep everything is SCT set to 0. The parameter is injector timing vs ECT. This parameter dictates when the injector fires in relation to TDC (stock is set to fire exactly at TDC). When you have aftermarket cams with overlap this is when you may want to adjust this parameter. There are a couple schools of thought as far as having the injector fire before TDC or after TDC. One thought is you want to fire the injector before TDC (or slightly before the intake valve opens) so you are firing the injector on a closed intake valve. The thought is that if you fire the fuel on the hot closed valve is aids in fuel atomazation (this could hurt cold engine drive-ability). The potential problem comes in when you have a more aggressive cam with valve overlap (with overlap the intake and exhaust valve will be open at the same time for a certain period of time). If you are firing the injector before the exhaust valve fully closes you are flushing fuel out of the exhaust (hence why you may get a strong fuel smell from the exhaust when the car is sitting at idle). So the other school of thought is to delay the injector firing so that it fires after the exhaust valve is closed. So, while the injector won't be firing and fuel hitting the intake valve at just the right time at least there won't be fuel going out the exhaust. This is one of those parameters that you need to play with. I don't think there is really a right or wrong answer...but adjusting this could help smooth out drive-ability. What you need to do is plug your cam specs into a calculator (duration, center-line, lsa, ect) and see exactly where your intake valve is opening and where your exhaust valve closes in relation to TDC. In my case I degreed my cams to Comps specs and don't have a lot of overlap. Then change the parameter in PRP. If you enter a negative value that makes the injector fire earlier (before TDC). If you enter a positive value it delays the injector firing (after TDC). According to my calculations and how I degreed my cams my exhaust valve is fully closed around 5* after TDC so I put 8* in PRP for my injector to fire a couple degrees after the exhaust valve is closed and go from there. I just wanted to touch on this as there are a few threads here and there. I'm not an expert on this but I believe this is the basics. [/QUOTE]
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