Hi all. I recently made a switch from Accel 36# (42 4 bar) to Mototron / Siemens Deka 60# (72 4 bar). I found 2 files on an LS forum labeled "Siemens Deka 60lb.hpt and Siemens Deka 60lb Data.hpt". Tried both, copied all Injector Control tables with a difference to my tune, as well as all Transient tables with a difference. Car starts and idles fine with both, but leans out big time (pegs out my old analog wideband in the car, I don't have it connected to HPT) and won't take any throttle at all.
I then found a file by ShorTuning in the Repository for "60# Mototron Injectors", gave it a try and had the same issue. Someone on the other forum (I believe he's a member here too) stated the VE table is likely off now and recommended I multiple the 1200 RPM column by 1.02 to see if it helps.
At this point I'm thinking I'm a bit over my head until I learn more, before I started the swap I thought I read just changing the injector data should be sufficient, didn't realize it could throw off the rest of the tune. I'm considering throwing the 36#s back in and the tune for those, and just getting the car down to the shop that tuned in to dial it in.
But.. if this is a somewhat simple fix I'm open to any info and advice, the thought of switching to the old injectors is pretty annoying. I also won't have a wideband to connect to HPT until Wednesday (don't really trust the old one currently in the car), not sure if all of this could throw A/F off and it's needed?
Another thing that's confusing is I left all of the tables the same in my 36# tune, and only changed the Flow Rate vs KPA table to the one from ShorTuning's file. The car runs pretty solid, if all of the other tables are necessary I don't understand why it would run so well, or even run at all?
Thanks to anyone that read this novel, and again any info is appreciated!
Tunes attached, before and after injector change(Injector change tune is loaded with ShorTuning's data attached in my original post). Fuel system is just stock LS1 with aftermarket rails (not sure on the brand, car has a FAST 90, could be FAST rails) and a Racetronix in-tank pump (255lph I believe). Setup is a speed density 12:1 N/A 416, LS3 bottom end w/ cathedral port TFS 225 heads, 250/258 .599/.599 112 cam, th400. Thanks!
Any recommendations before I put the 36's back in?
The car runs well with just the Flow Rate vs KPA table copied from the 60# tune. Any issues running it this way and not worrying about the other injector tables, if A/F is still dialed in? Thanks.
Once you have the VE map right, you just move injector global up or down until the new injectors work. If you have off-set (delay/lag time) data this is even easier because it wont wander much.
Thanks kingtal0n. Currently the car has great driveability and idle manners with just the Flow Rate vs KPA table changed for 60lb/hr (using ShorTuning's Mototron data in the Repo), the other injector tables match my original 36lb/hr tune.
My concern is WOT ..can only changing the Flow Rate vs KPA table affect the VE table and throw off A/F? Is there any harm in not changing the other injector tables if the car runs fine with only Flow Rate vs KPA changed (even though this isn't the "proper" way to tune)?
When you go WOT you should use Power Enrichment to bring the VE map's fuel value down to desired a/f ratio
dont fudge the injector flow rate table unless you know what you are doing.
For example if you went from 1lb to 2lb flow rate. Now it thinks the injector flows double so it will cut fuel in half everywhere. This also means conversely that when a fuel map VE value comes up, say it says 20 in the VE table. Well now since the injector flows twice you will only get half the fuel to that VE value. So if you modify the VE table to fix the injector table now the air mass calculations will be all messed up and nothing else will work properly. So the VE map needs to be true, and the injector flow rate curtails to it's needs, not the other way around.
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