I'm running 42.5 injectors and having a hard time scaling this thing right. Does anyone have a table for these injectors handy?
Thanks.... John
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I'm running 42.5 injectors and having a hard time scaling this thing right. Does anyone have a table for these injectors handy?
Thanks.... John
OK. adjusted the stock IFR table, multipied it by 1.19 and its pretty damn close now. A little rich at idle and cruise and a bit lean at WOT. Close enough for now.
Anyone have any tips for fine tuning the IFR table?
Like which ones need to be raised or lowered for the fine tuning....
back in the day thread but it's lookin like im gunna need help on this also
The proper multiplication factor is 1.18055, not 19%.
Why can't you jut put 42.5 in that table? if the injectors are 42.5 pound hour injectors then why can't you just put 42.5 in all the way across the table?
I don't understand why some cars have some scaling from 36.10 at 0-kpa to 38.40 at 100-kpa and other cars will have 38.16 all the way across on GTP's for example.
Sorry for the hyjack but it seemed like the right time & place to ask.
It depends on two things:
A. The pressure that the injectors were rated at and what they will be run at. If they were rated to flow 42.5#/hr at 43.5 PSI (3 bar) of fuel pressure and they will be run at 58 PSI (4 bar) of fuel pressure then they will be flowing more than 42.5 #/hr and the flow increase is not linear, it's exponential.
B. If the fuel system does not change the fuel pressure based on manifold pressure and manifold vacuum (boost and/or vacuum referenced) then the injectors flow more (at idle when manifold vacuum helps to suck the fuel out of the injector) or less (under boost when the fuel has to work against the manifold pressure).
So your saying 18.055%?Quote:
Originally Posted by JerryH
100% = 1
Hey 5 Liter Eater...
Seeing as someone else brought this topic up, can you answer this?
OEM L36 has the IFR set all the same in all cells.
L67, or at least newer version seem to have this "Ramping" IFR table.
A person with an L36 with boost (Turbo) should run which type of these tables? Ramping because now it's boosted? Still running a 1 bar MAP though.
If the ramping table is better how would you figure out the ramp?
Thanx,
Krunch
If the system is not vacuum/boost referenced (all returnless systems that I am aware of are not referenced) then the IFR table needs to be sloped. If you have a return style system that references vacuum and boost then you should have a flat IFR table because the regulator is accounting for the fueling differences based on manifold vacuum/pressure.
For the ramp rate, search for injector.xls and plug in your numbers and it figures it out for you. :cheers:
While I appreciate your answer, I must admit, I don't understand it:doh:
I'm not sure which of those two criteria is met on my car. My car has vacumm AND boost, but the MAP only sees from vacumm up to 1 bar, it doesn't see the boost. Some day I might upgrade to a 2 or more bar MAP, but not right now.
Could you clarify your answer better on how it relates to an L67 car with boost that the PCM sees, a NA car which has no boost at all, and my car that has boost, but only a 1 bar MAP.
Thanx,
Krunch
An injector works as an electronically controlled nozzle across a pressure difference. In an engine with a return style fuel system with a fuel pressure regulator with a connection to manifold vacuum/pressure the regulator keeps the pressure drop across the injector constant at whatever the "line off" setting is. This means for an engine under vacuum the fuel pressure drops to compensate for the pull on the engine side of the injector and when an engine goes to possitive pressure the pressure in the rail rises to compensate for the push on the injector. The MAP sensor has nothing to do with the injector tables as best I know (a bit new to the practical world of tuning these cars). When GM, and every other manufacturer for that mater, went to returnless systems for emissions reasons the rail is at a constant pressure and to maintain the same amount of fuel comming out of the injector the table must be skewed to match the change in pressure drop and the equivilent change in fuel flow. In this there would be MAP input but they didn't change that till the L29/32 in 2004.
This is interesting info. I've seen and heard only the 97 L67 PCM's use the flat IFR table, whereas 98 and up switched to sloped IFR tables. My 97 has flat rate and my 99 has sloped. I'ma have to look into thos a bit further now.Quote:
Originally Posted by 5_Liter_Eater
Indeed, you are correct.Quote:
Originally Posted by louvered97gtp
I switched my 97 over to the sloped table for IFR (amongst other matching changes in other tables) a long time ago.. Been using the sloped table for more then 1.5 years now.
Very well said.:usa:Quote:
Originally Posted by CTX-SLPR
Returnless fuel system=sloped IFR
Return fuel system (with a vacuum line attached to the regulator)=flat IFR
So, is the shorter, less technical answer...
The L67 uses a sloped IFR as it has a returnless fuel system, but the L36 uses the flat IFR because it has a return fuel system?
Now I suspect that just because I added a turbo kit to my car, there were no modifications to the fuel system itself to justify a sloped IFR, but again, I'm running a flat IFR in a car that wasn't boosted, but now is. Fuel demands are way greater now under heavy throttle conditions due to the boost.
I also know that if you made a change in IFR, you could undo that change again with MAF adjustments, so would running a sloped IFR in a boosted L36 produce a smoother looking MAF table?
Is running a sloped IFR table in a boosted L36 good or bad?
Krunch
To be honest I have no idea what the L36 and L67 are. You will need to verify whether each has a returnless or return fuel system. Acutally you just need to know what your car has.
Sure adding a turbo or blower will increase fuel requirements but this should not be accomplished by editing the IFR table. The IFR table defines how much fuel the injectors are flowing at different levels of vacuum (and on a natively FI car this table extends into boost).
So it was elegantly explained by CTX above and I made the very dumbed down version of it above.
Returnless fuel system=sloped IFR
Return fuel system (with a vacuum line attached to the regulator)=flat IFR
So if you know what type of fuel system your car has and what size the injectors are (as well as what pressure they were rated at) then you can determine whether to use flat or sloped and what numbers to use.
L67 is a return type fuel systsm. L32 is returnless.Quote:
The L67 uses a sloped IFR as it has a returnless fuel system
Really?? wow... I didn't know that the L32 doesn't have a return.Quote:
Originally Posted by JFDugal
Ok... knowledge adjustment is now complete... Thanks for the info guys.. ;)
Sorry but I seem to be a bit thickheaded in trying to figure this out.Quote:
Originally Posted by 5_Liter_Eater
So i have Siemens 60# injectors rated at 43.5psi
I have a 99GTP with return style fuel system and vacuum on stock FPR
Based on this I should have a flat graph line in my injector table but I don't. What are the consequences of this?
Also, how is the sloped rate properly calculated.
Stock GTP injector 36lbs divided by new injector 60lbs, so 60/36=1.6667
We multiply our current injector by new upgraded scale factor..
36x 1.6667 = 60.012 lbs new IFR linear chart?
Now, If the above is correct, how do we turn this into a sloped table? We don't use the HPT conversion chart do we. It asks for current and new fuel pressure. Most of us change injectors, not fuel pressure so this conversion chart seem useless you raise fuel pressure correct?
Yeah, it's not making sense to me either. I understand what is being said, but the L36 (3800 NA) and L67 (3800 SC) are both return fuel systems, and by that rationale should both have flat IFR. Although in practice, they don't...why not?
And krunchss, this may be a silly question, but if you've got the ability to tune, why are you still running a 1 bar MAP on a boosted engine? You could start with an L67 tune and work it from that, right?
I'm assuming 5_liter misspoke up above, but it doesn't have anything to do with the return system directly. You aren't going to have a vacuum referenced FPR on a returnless system because your FPR is in the back of the car by the gas tank.
If your FPR is vacuum referenced then your IFR is flat. If it isn't, its sloped.
You figure the flow rate of the injector using the equation here: http://www.rceng.com/technical.aspx?...ressure_Change It's not just a multiplier. Whatever number you come up with there is what the injector will flow at atmospheric pressure.
As CTX said in post #11, basically under vacuum the fuel is bing sucked out of the injectors, effectively, virtually increasing the fuel pressure so the injector flows more. Under boost the injectors are having to push against the manifold pressure, effectively virtually decreasing the fuel pressure. So, to get the slope of the line you simply add or subtract the MAP to/from the rail fuel pressure. So a 60# injector rated at 3 bar (43.5 PSI) running at 4 bar (58 PSI) would flow ~69.3#/hr (at atmospheric). Say it idles at a MAP of 55 KPa which is ~8 PSI of vacuum then you'd add 8 PSI to the 58 and re-calculate and you get ~73.9#/hr.
Now, if the system is return style and vacuum referenced then yes, the IFR should be be flatlined. Thats because the regulator is lowering the fuel pressure for you at a 1:1 ratio to MAP PSI. So 5 PSI of manifold vacuum would reduce the fuel pressure 5 PSI so the equation would not have to take the 5 PSI of manifold vacuum into account and you'd have the same value as when it's run at atmospheric. The consequences of running a sloped IFR table with a vacuum referenced return style fuel system is incorrect fueling (too much fuel) getting worse and worse as vacuum increases.
Making more sense now? :cheers:
Quote:
Originally Posted by louvered97gtp
Clear as mud 5_Liter_Eater :P
I was going to just leave this thread alone as the more I read, the more I got confused. But as eclipse5302 said, both the L67 and L36 have the same fuel system, but one has a flat IFR and the other has a ramped IFR. So, back to my original question...
Should I be running a sloped IFR on a boosted L36 that was originally NA?
eclipse5302, I do plan to consider trying the L67 bin at some point, as there are a few things I could benefit from such as the MAP, and I think the spark tables also have better resolution just to name a few. I guess I don't mind reading my bin and it then say I have a 2002 Grand Prix GTP instead of a Monte Carlo. Before I make the change, I need to decide on the best bin match for my car as there was no 2002 L67 Monte Carlo :P I'll worry bout that later, but few to no people have told me to upgrade to a bin that supports 2 or more bars, so I question if it's really necessary for my car or not.
Krunch
Oops! Missed this post :banghead:
So are you saying that even though my L36 that was originally NA should STILL run a flat IFR even though now I am boosted?
Krunch
Quote:
Originally Posted by SMOKINV8
Quote:
Originally Posted by krunchss
Hmm. So how is the car getting more fuel / less timing with boost? Are you running a very small amount of boost? Do you have some other method you are using? I don't doubt what others have said, I just want to understand why that's all.
As for the best match, I would think that a 2002 / 2003 GTP bin would work fine, regardless on the make of car. I know it's not apples to apples, but my 1991 Cutlass Supreme is running a 2002 GTP L67 bin. Of course, the timing tables are from a 2005 GTP, and the VE and MAF tables have been tuned specifically to my engine since it's cammed.
You'll have to forgive me as I'm not familiar with these vehicles, but the concepts are the same. To be sure I'd hook up a fuel pressure gauge to verify whether fuel pressure is dropping with vacuum and increasing with boost. If it does then use a flat IFR with whatever number the spreadsheet gives you for 0 kPa. If it doesn't change then use a sloped IFR using the numbers from the spreadsheet.
I'm not sure why two cars with the same fuel system (return style, vacuum referenced) would have two different types of IFR tables. It wouldn't be the first time GM has messed up. There is no reason to increase IFR as vacuum goes up if the fuel pressure is physically being lowered.
Does the L67 bin have an IFR that covers vacuum and boost where as the L36 only goes from atmospheric to full vacuum?
Those are very good questions eclipse that I'm afraid I don't have the answers too. It was originally a Cartuning turbo kit (I only say that when I have to) that I have added a liquid intercooler to, well, 95% complete. All I can say is that NONE of the Cartuning kits came with upgraded map sensors. Once people have gotten Kevin's crap tuning straightened out, some people have gotten the kit to work quite well. That's the best I can say. Someone else here might have a better answer for your question. I don't have a lot of knowledge of tuning past VE / MAF yet, I just really haven't focused on that yet until I can get my IC setup complete then do some VE / MAF tuning to straighten out my fuel which on average right now is pig rich without the intercooler. I figured I would jump into this thread as I hope to calibrate my IFR to my DIC soon before I start VE / MAF tuning, and if the sloped IFR was better for my boosted L36, better to make those changes now instead of backtracking later.
Krunch
Quote:
Originally Posted by eclipse5302
I don't know about the L67 tune starting since an L67 has a 4T65E and an L36 has a 4T60E which have some different stuff in and on them. I don't think he needs the BBV stuff that the L67 has so that's not a miss.
Actually my car came OEM with the 4T65E but I have since upgraded to a ZZP trans with 2.92 and 3000 stall which is in essence a 4T65E-HD now with a 3000 stall. I don't follow what you're getting at that the IFR would be related to the trans however, and dumb question, what's BBV :P
Krunch
Just an add to the post that eclipse made above...
You asked if my boost level was low? Depends on your defination of low...I run the 9 psi that Cartuning set this kit up at when I bought it. I'll see if I can safely up the boost later after I address other issues in this tune.
Krunch
BBV=boost bypass valve
Trans relation, GM E-series transmission require trans specific programming meaning that an ECM with code for a 4T60E would not be capable of running a 4T65E. I didn't know that Monte's got 4T65E's as most L36 FWD cars had 4T60E's.
Quote:
Originally Posted by 5_Liter_Eater
I have an 04 L67 and the Injector Flow Rate vs. KPA VAC only goes up to 100 kPa. Mine is sloped.
I can't tell you exactly what to do on that one. If I were in your shoes, I would start with a sloped IFR and go from there. If you end up having to lean out the fueling tables (especially the MAF), then that should indicate you should be running a flat curve.
Here's a question for you. I know the L36's have a vacuum referenced FPR. Do the L67's as well? If they don't, that would certainly explain the discrepancy. Also, which FPR are you running on your car now that you're boosted?
My car has no BBV then as OEM it was NA. Only the L67 (supercharged) would have this I expect.
Krunch
Quote:
Originally Posted by CTX-SLPR
If you're talking to me, my car after the turbo install still uses the OEM FPR. No replacement was included nor suggested with my turbo kit.
Krunch
Quote:
Originally Posted by SMOKINV8
That's odd? You have an OEM boosted car and the IFR only goes to 100 Kpa? The GTPs IFR DOES go higher than 100 Kpa right? Your IFR ramp is what I expected from an L67 though.
Krunch
Quote:
Originally Posted by mtcrusan
Thats 100 kPa of vacuum.Quote:
Originally Posted by krunchss
It doesn't matter if it is returnless or not. Take the "mode" of all the LTFT values for each MAP range, 20-29, 30-39, etc, and then scale the fuel flow accordingly to bring it back to 0. Mine are extremely tight. I have a spreadsheet I plug the MAP values in and the existing table and it gives me a new table to put in. With this I can get my LTFT's within 2%, most often, 0-1%, it is rare to get out of that.
At low vacuum or high, most NEED to be scaled anyway. Has nothing to do with returnless or non returnless fuel delivery at all.
Quote:
Originally Posted by eclipse5302
While you may be able to gleem some results from that I think the method is a poor way to go about it. How do you know the fueling errors (fuel trims) are due to injector flow rate inconsistencies and not air metering inconsistencies. If you were running speed density then you could make up for incorrect IFR values (sloped when it should be flat or vice-versa, or just improper values altogether) with the VE table but if you're running a MAF then it's independent of RPM and MAP. So if you have stock injectors and put headers on you're telling me you're going to change the IFR table to get the trims back in line? The flow rate of the injectors hasn't changed.
There are two variables in tuning AFR; fuel and air. There are several tables you can edit to change the amount of fuel being injected but the IFR is not a good one to use. The injector flow rate is an equation. Assuming the injectors are clean and reasonably balanced then it doesn't make sense to change the IFR at particular MAP regions to deviate from that equation. Even if they are dirty and not balanced it doesn't make sense to try to make up for that be editing the IFR. Use the airflow table to change the amount of fuel.
:cheers:
Exactly why I take the MODE of it, not the average/mean, that would toss you all over the place. Think of it as the coarse adjustment. Then once you are fairly tight with LTFT's then you make some fine adjustments if needed with MAF/Airflow tables. It is all math, just where do you change the values at. MAF/Airflow table should be last adjustment not first.
Look at it this way, our cars are tuned factory with real gas, not 10% ethanol gas, so in most cars the LTFT's are off out of the factory, just because some idiot politician decided that they know more about tuning cars than we do and force gas on us that we don't want. So tweak the Injector Flow to tighten up where it should be, and then you shouldn't even need to touch anything else.
Is there enough bandwidth in the PCM to handle 10% ethanol? Yes, the newer the better it handles it. But older PCM's don't handle it near as gracefully.... Which makes having a sloped injector flow rate so helpful.
Quote:
Originally Posted by 5_Liter_Eater