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Thoughts/Suggestions on FAST 102 for FI Application
I HAVE a 102/102 combo on my car. That's what's driving this.
When I sold the car in 2010, it had an LS6 intake and lightly ported TB, stock MAF on the car and had zero problems being tuned and acting normal. When I bought it back last year, it had been upgraded to a LPE 100mm MAF and Fast 102/NW102 combo (among other things being 95lb/hr injectors, LG upgraded turbo's, and driveline stuff). Talking to the P.O. who did the upgrades, he informed me that when that combo went on they were getting split fuel trims under boost hence why the LPE MAF was tuned out and the car was finally given an OLSD tune. They did some other janky stuff I'm trying to undo (as in lowering the base fuel pressure down to about 33-35 PSI in order to attain what his tuner though was an acceptable idle with 95#/hr injectors).
What brings me to this is the fact that I'm still fighting an awful issue on Bank1 where it's simply running god awful rich randomly and fouling out the plugs. Wide band and scanners both show this to be true as well as my pitch black fouled plugs. I'll be cruising down the highway and one minute it'll be reading 13.8 to 14.2 under speed maintaining throttle and dump to 10.0 when I lift, then halfway through my trip it'll flip and start reflecting 10.0 on the wide band under speed maintaining throttle and come up to 13.8-14.2 range when I lift. Won't flip back until after the car cools off.
The FAST was opened and sealed up by the P.O. prior to it ever going on the car, and though I haven't pulled it yet to check, he is under the impression I won't get it apart without breaking it.
Given that the split trim/tuning issue showed up when the 102 setup went on the car, I'm REALLY considering moving to a ported LS2 manifold and 90mm combo, ditching the aftermarket AFPR in lieu of going back to a 97-98 return style rail like I had before, and having it retuned.
Anyone with some potential thoughts or insight for me before I just arbitrarily take the plunge?
I would change like you are thinking, why fight all those issues. I was thinking the LS6 was better than the LS2 intake manifold, but maybe I am thinking of something else.
Swap injectors left to right and see if problem persists, or have them flow tested.
Although moving from a carb intake/elbow on my car to a BBK SSI intake really helped AFR's bank-bank.
With the carb intake they were bloody terrible, sometimes as much as a full AFR point difference, and at heavy loads often 0.5 AFR difference, with the right bank always being richest.
With the BBK its around 0.3AFR at worst but most of the time they're within 0.1 AFR of each other, the right side again being the richer.
I may try swapping injectors. I'm almost wondering if it's an atomization issue under solid vacuum cruise levels.
What I'm hesitant to do the move for is how much power I may leave back on the table moving down from the 102 to the LS2 stuff.
With boost, it really isnt anything another pound or two of boost wont sort.
If turbo'd though, the additional improvements off boost may still be desirable with the better intake, and the better intake would also improve rpm ability up top.
If a supercharger, even though a centri may not appear to make positive pressure at lower rpm's, it is still very much assisting airflow. So the only consideration would be the upper rpm help the FAST might offer as the supercharger will take care of any concerns lower down
I HAVE a 102/102 combo on my car. That's what's driving this.
Given that the split trim/tuning issue showed up when the 102 setup went on the car, I'm REALLY considering moving to a ported LS2 manifold and 90mm combo, ditching the aftermarket AFPR in lieu of going back to a 97-98 return style rail like I had before, and having it retuned.
Anyone with some potential thoughts or insight for me before I just arbitrarily take the plunge?
I honestly don't know. I would assume so as the manifold was purchased new, installed at the tuners shop, etc. I wasn't privy as this was happening as the car wasn't mine at that point. I have checked externally for vacuum leaks though and didn't come up with anything, so my assumption is that the short bolts were indeed used, for now. I'll probably be taking the manifold off and opening it up sometime in the coming weeks.
What do the narrowband O2 sensors look like or are they not even hooked up now? What are the injector pulsewidths logging when this issue starts occurring?
Forgive me but I don't have BPW access as I'm using a Snap On Solus Ultra and I don't remember seeing BPW last time I was running through.
Bank 2 was switching normal from about 80 to 900 mV. Bank 1 was only switching from about 80 to 350 mV and slowly at that. The pic below are plugs 1 and 3 (the silver is just anti-sieze, these plugs only had about 500 miles on them if that).
I'm looking at the manifold because it caused issues when it went on the car by what I was told, hence the OLSD tune as it currently sits.
Just pulled the manifold, and yes, the button head valley cover bolts were indeed used.
Can't say I'm crazy about the clearancing on the firewall though:
Not my work for sure. I found grey RTV freaking everywhere, every single port, squeezed out the manifold seams, etc. The Grey I know not to compress very well so it's possible this could be the issue itself. That and the face that it took NO breaking pressure to take the manifold bolts free. I don't think they were torqued to spec.
Still, I think I'm going to move back to a LS2/90mm combo just to clear up any chances for manifold boost leaks. Plus side is I can run the 97-98 return style rails again too (with some minor work) and clean up the bay some.
WTF... That is butchered for sure. Sucks to find that on your car.
Good luck with the upgrades.
Yeah, I knew I was in for some kind of nastiness with the reflective barrier I could see on the top side, but dang. Didn't expect that. I'm going to have the whole top of the motor out so I'll probably do a fiberglass patch on that area since I'm moving down to (probably) an LS2 manifold/TB setup. Ported of course.
Cooked 3m weatherstrip adhesive on the runner to nameplate mating surfaces. Dried and definitely not sealing anything together as I can wiggle each end. I see now why it was getting split fuel trims under boost.
Manifold appears to be in great shape save for needing to be completely torn down and sealed up again. Questioning if I should push my luck and reuse this stuff or go for the more proven less problematic ported LS2 and 90 combo.
09-11-2016, 11:21 AM
Thoughts/Suggestions on FAST 102 for FI Application
Didn't expect that. I'm going to have the whole top of the motor out so I'll probably do a fiberglass patch on that area since I'm moving down to (probably) an LS2 manifold/TB setup. Ported of course.
