Anyone running an LE5 with 42lb injectors? I'm going to be supercharged in about 3 days so I'd like to look at the tune and get an idea of what I'm getting into. I have an LC-1 hooked up and ready to go. Supercharger isn't in yet.
Anythign specific I should know about tuning the LE5 for larger injectors (or anything for that matter) before moving on?
You would have to go into the injector flowrate vs KPA table, and multiply the differances bettween the stock table by 1.75 Now the car should eun right with the injectors, but then you are going to have to tune the MAF. Thats about as much as I know with the injector's since I have dont anything with the injectors. Maybe some one else will jump in. Still new to HPT myself.
Thanks, after reading alot of the how-to's on here I got that part and your post cleared it up for me. Hopefully this will at least get the car to run, and I can monitor the A/F ratios while driving (er...have my passenger monitor). I'm not quite sure where to begin with tuning the timing.
I also read somewhere, that every time I write the PCM it has to be a full write?
For the timeing I would leave it stock for now tull you can get driveablity down. And yes you have to do an write entire every time on the LE5.
i too was puzzled by how to set IFR..........i still don't know how much "play" room......or how to determine the variance ( as in what pid determines the need ?)Originally Posted by REDFOCZ
since guessing we have similar cars ( mine = 2.4 , e67, 42 lbers) ....i was curious to see where the ( multiply by 1.75 ) would put my IFR.........
and yes it falls right in on the "highest" range of settings i have tried....
mine are set much l lower now ( ty russ ) ...
.. and i have been told always rescale the same way as the original......( so a multiply by # sounds right in keeping stock scale.
strictley per these 42's - adding 14 str8 across pretty much leads to same as the settings russ gave me ( altho russ has a more perfect linear plot than stock )
i assume the more conservative settings have some complicated explanation ....and justification .( pulse widths etc )...better than my understanding that the ecm thinks they are smallerand thats good ?
anyone care to explain / expand on when to use conservative settings or when the higher ones are the optimum choice ???........ yep i'm a noob but don't think i ever maxed out any 90 % range ??
where did the 1.75 multiplier come from ..( experience or ?)..is there a range on that ? or a simple explanation when to lower the multiplier
2.4 ecotech ( 2006 pontiac solstice )
42lb injectors
trim 50 garrett t3t4 (custom -barebones pumpking )
boost @ aprox 7 <10
38mm tial wastegate and bov
3" tubes front to back
werks radiator
bell intercooler
GXP,magna flo exhaust-with integrated dumptube by B_FASTER & R&D
aem wideband
custom manifold -by sh**er the skunk
(((HP ))) tuning -in progress
jet hot 2000
aerospace logic egt kit
The best way to determine IFR would be with an injector flow bench. That table is there because the General uses a fixed pressure system (58psi). And since it's fixed relative to the atmosphere, the flow rate across the injector changes constantly with engine vacuum. IE the injector flows alot more with high vacuum (low kpa) becuase relative to the injector orifice the pressure drop is much higher.
58 psi base + total vacuum (-14.7 relative to outside or 0kpa)=72.7 psi drop across injector.
On the opposite end, 58psi base pressure +14.7psi boost (2 bar absolute or 210kpa))=43.5psi drop across the injector.
What all the mumbo jumbo means is that at full vacuum your 65 is a 72.7lb/min
and at 1 bar of boost it's a 56.29lb/min injector. Now you see why that table exists and why it's so important to get right. The PCM needs to know what size injector it's firing.
The simplest way ot get your numbers is to use the injector calculator in the Editor program to figure out your table. If your using a 1 bar map sensor use the kpa at the top of yor table to figure out what your pressure drop is across the injector. If your "faking" a 2 or 3 bar make sure you figure out your drop accordingly.
Personally I usually end up installing a boost reference return stlye fuel system and putting 1 constant across the board, as the pressure drop remains constant.
Oh I almost forgot, flow rate and pressure are NOT a linear relationship. It takes 4 times as much pressure to get double the flow thru an orifice. You must calculate each datapoint, it should look like a curve, not a line. a 1 bar curve will be barely noticible over 12 datapoints. a 3 bar curve will have much more arc.
It's a 2 bar map sensor. I need the car to run (safely) and from there I will tweak the rest of the tune. I'll play with the chart and see what I get out of that.
What is the injector constant on the LE5 stock?
Last edited by pjk91; 08-26-2007 at 09:01 AM.
zzzybil
To make it flow properly for the 42# injectors, you have to know the stock injector size (24#) So when changing the table you take:
42#/24# = 1.75
Highlight that entire table, then multiply it by 1.75 and you will be good to go.
That is how you calculate flow rates on injectors, and it should be properly adjusted for the right flow of the injectors. The thing to watch is your LTFT in the scanner, they should be close to Zero.
Again this is just from what I have read, I have no experance <(sp) in doing this.
Honestly I dont know, but if your using 42's I'm pretty sure that they are rated @43.5psi. That should make your top number @100kpa (that is actually 200kpa) 42 lbs/min. at full vacuum of 0kpa your 42's flow 54.37.
That is unless the general is counting backwards, IE 80kpa "vacuum" = 20kpa MAP sensor reading. Bill or Chris can chime in and confirm
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