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Installed 60# mototrons, Fuel Trims are way off

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Old 02-10-2006, 07:13 PM
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set minimum pulse width to 1.0, it will get much better. i'm not sure what the minimum pulse width is, but last time i tried it on 60#'rs it worked
Old 02-10-2006, 07:30 PM
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RedHardSupra - will 1.0 be enough for a 60# ? I mean I was thinking of half the whole table, but dont know if Im going to be hurting something.

SmokingWS6 - I will try dropping the short pulse adder by say 20%, but I think the key is dropping the minimum pulse width and default down to at least 1.0 or even below that.

Am I wrong in my math to assume on the decel (going from stock z06 injectors to 60#) that I should be close to almost 0.8 msec? If Im right then Id have to definetely half the min pulse width table and default cause the short pulse adder will bring it close to 0.8 msec when its done.

Dixit
Old 02-10-2006, 07:40 PM
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scientific principles: go in small systematic steps, change one thing a time.
i have practical experience where this approach made 60# injectors made not dip deep into rich territory on decel with 1.0 we haven't tried any lower, but that brought it back to acceptable range. i know SVO's can go down to 0.9ms, i can't find any hard data on mototrons tho.
Old 02-10-2006, 07:46 PM
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RedHardSupra - I agree with you on changing it little till I get it right. So when you worked on them did you just change the Minimum to 1.0 and it solved it? Did you have to drop the default as well? Seems like you would. Any other changes you made, or just the min. pulse width? Thanks for you help.

Dixit
Old 02-10-2006, 07:59 PM
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one thing at a time: lower min to 1.0 and watch you wideband.
Old 02-11-2006, 02:09 AM
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I had to lower the Default on this particular fbody ls1. I would predict the c5 would respond in the same manor. I set the min to 1.05 if I remember right.

I strongly agree with one step at a time. If you dont know what each change effects you can quicly become burried in problems.
Old 02-11-2006, 01:20 PM
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Originally Posted by Dixit
Yeap that is the only thing I changed. I remember seeing a post of "gameover" who said that he went from stock injectors to 60#s and his fuel trim didnt change.

Im not sure now if I should use the first set of values and basically have to redo my entire VE and MAF table or should I just scale the Injector table till the trims get back inline. Before I did the swap the Ltrims were between 0 and -4, idle was normally around -2, after the injector swap it was sitting around +18. These are rated at 43.5psi.

Dixit
You don't need (or want) to redo your MAF and VE tables for new injectors. That is totally wrong. You only need to work on your injector slope and injector offset tables. That and lower your min pulse width.

Good luck, Ed
Old 02-11-2006, 01:47 PM
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I'm familiar with the injector offset tables but I'm not sure which tables involve the injector slope???? Can anyone elaborate on this???
Old 02-11-2006, 01:55 PM
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Ed, I agree with you on not needed to change the MAF or VE table at all. However, I have no clue what to set the injector offset to, ive searched and read some of Jimmyblue's posts, but his posts are so indepth that I think I come out more confused than before hahah, he writes alot of detail. I need a dummies version of his posts.

Dixit
Old 02-11-2006, 03:47 PM
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Originally Posted by hc_performance
I'm familiar with the injector offset tables but I'm not sure which tables involve the injector slope???? Can anyone elaborate on this???
That is the injector flow rate table, it is sloped vs manifold vacuum. Everybody I know calls it injector slope. Sorry if I was not clear.

Ed
Old 02-11-2006, 03:51 PM
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Originally Posted by Dixit
Ed, I agree with you on not needed to change the MAF or VE table at all. However, I have no clue what to set the injector offset to, ive searched and read some of Jimmyblue's posts, but his posts are so indepth that I think I come out more confused than before hahah, he writes alot of detail. I need a dummies version of his posts.

Dixit
Scale the table by percent. System voltage vs MAP. Large injectors are typically lazy, needing more offset.

Good luck, Ed
Old 02-11-2006, 10:10 PM
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Originally Posted by Ed Wright
Scale the table by percent. System voltage vs MAP. Large injectors are typically lazy, needing more offset.

Good luck, Ed
Dixit - in light of Ed Wright's instruction you may find this old thread of value -> https://ls1tech.com/forums/pcm-diagnostics-tuning/44201-injector-offset-definition.html . NoGo used fuel trims to adjust the offset table. Should be pretty easy to setup a Custom map with EFILive to do what Ed says.
Regardless, Let us know how it turns out for you and your method .



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