Help! Am I running out of fuel?
Help! Am I running out of fuel? I've been getting used to Hptuners and just logging information to see how the motor reacts to different things. I noticed my 02's were reading in the 870's at WOT in the upper rpms. My FT's are pretty much inline so I tried to adjust the PE table to comand some more fuel.
I did a log today and at WOT in 3rd/4th gears I'm getting about 17.7-18ms at wot from 5500rpms to my 6500rpm shiftpoint. I'm in a 2004 GTO so I'm not sure how much the injectors are good for. If 18ms at 6500 rpms is equal to 100% duty cycle I'm about maxing them out now?
I looked on the chart in the scanner where it peaks 18ms is at 5600rpms which is my tq peak where at the dyno the reading was 13.1 afr and leaned out to 13.5 by 6500 rpms. Am I correct in thinking that changing anything in the PE table isn't going to help at all because there is no more fuel to be had. On the PE table I'm commanding less fuel after 5600 rpms so that makes sense that the O2 readings went down to 17.2 by 6500rpms.
The o2 sensors start out reading 880-890mv up to 5200-5500 rpms and start to dip into the 870's by through redline. I posted a copy of my dyno chart as well. I really need some help on this one guys. I didn't think it was an issue because of all the 440-460 whp ls1 still running stock injectors. Thanks in advance.
I did a log today and at WOT in 3rd/4th gears I'm getting about 17.7-18ms at wot from 5500rpms to my 6500rpm shiftpoint. I'm in a 2004 GTO so I'm not sure how much the injectors are good for. If 18ms at 6500 rpms is equal to 100% duty cycle I'm about maxing them out now?
I looked on the chart in the scanner where it peaks 18ms is at 5600rpms which is my tq peak where at the dyno the reading was 13.1 afr and leaned out to 13.5 by 6500 rpms. Am I correct in thinking that changing anything in the PE table isn't going to help at all because there is no more fuel to be had. On the PE table I'm commanding less fuel after 5600 rpms so that makes sense that the O2 readings went down to 17.2 by 6500rpms.
The o2 sensors start out reading 880-890mv up to 5200-5500 rpms and start to dip into the 870's by through redline. I posted a copy of my dyno chart as well. I really need some help on this one guys. I didn't think it was an issue because of all the 440-460 whp ls1 still running stock injectors. Thanks in advance.
OK, I'm assuming they use the same standard 28#ers for the GTO right? If you're pushing 100% duty cycle you're not necessarily going to "run" out of fuel, since that's as bad as it can get it seems at this point. The problem is though, if you do more power mods then you may not have too much flexibility since you are right at the edge of of your injectors functional capabilities.
Good practice would be to not exceed an 80% duty cycle, but I for one know that many people do not heed this (me included... I push 90-100% but only near redline... lol). All it means is that life expectancy of your injectors will probably decrease. (yeh, that's all...
) I'm gonna go with some 28#ers myself (I run 26#ers) just to free up some of the load.
BTW, narrowband readouts aren't too indicative of rich/lean beyond stoich measurement. This means that a value of 890 could mean 12.0, 12.5, 13.1, 13.3 so it kind of hard to tell. You are pushing a bit more power than I am, and I know that I am close to maxing out my effective injector flow. If you stay with the setup you have, then perhaps pushing your injectors at max only near redline isn't terribly bad, since everywhere else they're well within specs. Although that's when your fuel pressure is greatest and if you constantly overload your injectors, they will take a dump sooner or later. Figure out how many horses you want to have (if there is ever enough!) and then decide how to sustain it from there!
Good practice would be to not exceed an 80% duty cycle, but I for one know that many people do not heed this (me included... I push 90-100% but only near redline... lol). All it means is that life expectancy of your injectors will probably decrease. (yeh, that's all...
) I'm gonna go with some 28#ers myself (I run 26#ers) just to free up some of the load.BTW, narrowband readouts aren't too indicative of rich/lean beyond stoich measurement. This means that a value of 890 could mean 12.0, 12.5, 13.1, 13.3 so it kind of hard to tell. You are pushing a bit more power than I am, and I know that I am close to maxing out my effective injector flow. If you stay with the setup you have, then perhaps pushing your injectors at max only near redline isn't terribly bad, since everywhere else they're well within specs. Although that's when your fuel pressure is greatest and if you constantly overload your injectors, they will take a dump sooner or later. Figure out how many horses you want to have (if there is ever enough!) and then decide how to sustain it from there!
Last edited by txhorns281; Mar 12, 2005 at 11:14 AM.
