I've finished tuning the VE and was about to start tuning the MAF. I went for a drive to get a base log and noticed the O2's constantly swinging up and down. I checked some older log files and the O2's have a much smoother rise and fall. I've attached a log and my tune file. Any ideas what could cause this?
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
Looks normal to me for closed loop operation.
Side note, you are way out of injector too. 105% duty cycle at only 5,000rpm.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Thanks, I may have been comparing the log file to an OL one, thanks for catching that.
I noticed that the injectors were pretty much maxing out - where did you get the duty cycle % from? All I go by is the gauge on the scanner.
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
Your charts vs time are showing the duty cycle at the top box with the rpm/speed.
I rarely watch the "gauges" unless I need to see something super big. Personal preference I guess.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Thanks, I see it now.
I was hoping that I wouldn't have to change the injectors. From what I've read on here, it seems like a can of worms.
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
Only a can of worms if you buy bad stuff.
If you buy factory replacement injectors that are larger than your stock ones, everything is plug and play for data. Nothing can really be screwed up at all. Then just tweak the fueling if required.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Is there a resource that I can use to determine where to get bigger injectors. I'm thinking the local U-pull yard will have something if I can determine what it is I'm after. This is all new to me, I don't even know what size injectors are in it now, I need to educate myself on this.
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
Stock 6.0 engines from that year run 25lb/hr injectors, I don't know the part number of them off hand. You can view what comes with what flow rate by looking at the flow rate vs KPA table in the file.
Again I don't have part numbers on me but the easiest ones to find come off a few different stock vehicles.
An LS1 car like a 2000+ come with 27-28lb/hr I believe. A stock flex fuel silveardo/tahoe/suburban from like 2003+ run 33lb/hr injectors. Then you also have the 8.1 vortec from the heavy duty line that run 31lb/hr injectors. I'd go the 31 or 33lb/hr injectors personally, they should be plenty big.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Thanks for the info. I did find some information online, looks like a bit of rewiring will be in order as well as the early gen III trucks have an oddball connector. Knowing that I should be shopping for 31-33# injectors helps narrow that down.
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
I pull/keep ALOT (300+?) of various LS junkyard injectors around for 'stuff'.
If you want to upgrade to 33/lb its pretty easy. Just find a flex fuel truck (VIN 8th digit is Z) with the same rail type as you have (either return or returnless - ive seen flex in both flavors) pull the rails, injectors, and either get the injector plugs from the junkyard and rewire your harness, or buy adaptors online (they plug right in).
This assumes you have a truck intake, if you don't then the fuel rail adaptation is up to you.
I do have the truck intake so the fuel rail has a return line.
Do you know if there is such a thing as a 31 or 33# injector that will plug into my 2000 Silverado harness?
If you had a set you'd be willing to part with we could make a deal.
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
If there's a 31 or 33 lb that will plug in, I haven't seen one. Possibly from something other then a truck.
The trucks only came with the shorter 25lb non flex and the taller 33lb flex. Theres multiple part numbers but they're all the same flowrate unless there's some oddball that I haven't seen, and I see 10-15 truck engines a week, so it would be something rare.
I don't sell injectors, plus its probally against the forum rules? You need to hit the junkyard or ebay for the fuel rail anyways, the flex fuel injectors are taller.
Well, that clears up some of my confusion. I need to narrow down what year truck I'm after as the local u-pick yard lists them by year.
Didn't know there was a no selling rule on the forum, thanks for letting me know.
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
Is there a way to adapt the shorter truck injector rails to fit the taller Flex-Fuel injectors? (with some kind of spacer)Originally Posted by BrianPeppers
Barring that, will the taller Flex-Fuel injector rails swap directly into the truck intake that fits the shorter injectors?
55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.
Reply With Quote