Advice:427 supercharged LS9 injector/LS7 MAF

[exploder]

I am just looking for a little guidance here. I have a customer that brought me a 427ci LS7 forged motor and also a A&A Ysi supercharger kit/ LS9 injectors modified for 80lb flow and a LS7 MAF. I have already installed the motor and cranked it up with its old stock tune without the supercharger. It ran fine and everything but it would not run with the LS7 maf plugged in; only with the original (as expected).

What I am trying to decide is whether or not I want to jump straight into just doing a hack job maf after it maxes out or should I just go straight 2 bar. If I use the MAF where and how do I start tuning it? (do I just plug it in and start autoMAF or is there something else that I need to do to make the LS7 card MAF work).

The customer also brought me a set of modified LS9 injectors that are supposed to flow around 80lb/hr. Are there any IFR tables for these injectors or some like them? Or do I just use the IFR spreadsheet and make and educated guess?

I am attaching a copy of the original tune file unmodified by me from the last tuner. I will appreciate any advice on these aspects and was also interested in if I did go SD for the customer if the STFTVEcalculated PID is a good way to go or if there is a new way better than AUTOVE or STFTVEcalculated?

[joecar]

If you can copy his tables into a 12212156 file (F-car if he has cable throttle, Y-car if he has DBW) and get it running the same, then you can jump to COS5 and install a 2 bar MAP sensor.

Regarding LS7 MAF: try adding or subtracting 10% and see if it runs... I don't know how the LS7 MAF table is scaled, but if you can get it running so you can log MAF g/s then you know how to adjust B5001. How much time do you have to play with the MAF...? When you have the LS7 MAF on there, do any DTC's show up...?

Also fix the all of out of range cells, they make the PCM do extra processing.

Send me your email address, I'll email some spreadsheets for LS9 injector tables mapped to LS1 tables.

[odd boy]

Joecar,

please post these files and make them sticky. I am interested too

[joecar]

These are the injector tables from LS3/LS7 and LS9 interpolated to fit the LS1 injector tables (paste-with-labels)...

LS3/LS7: GM calculated B4001 based on rail pressure 58.0 psi.
LS9: GM calculated B4001 based on rail pressure 61.4 psi.

So for LS9 you may want to either run 61.4 psi (if you can) or rebase B4001 for 58 psi.

[Redline Motorsports]

Well here we go again...............the injector data is probably no good with injectors that have been modified from that data point.

How much power to do plan on making? A set of 63.5" (@3 BAR) will support 950 RWHP FI with a rise and rate fuel system.

I don't know what year the processor is but I'm sure you'll hit the limits of the MAF unless you either re-scale the calibration or ditch it for a 2 BAR setup.

You can't just unplug the MAF as it also has the IAT built in. If it doesn't run with the MAF disabled, then the VE is off good.

There are some tutorials available that should get you going.

Howard

[joecar]

Oh, I didn't see "modified" in post #1... sorry, my mis-read... Howard is correct.

[exploder]

We are shooting for around 850whp. The car is an 01 model as far as OS goes currently. I guess I will just have to wait a few more days until I get all of the injectors here and go from there. I am also going to seperate the IAT sensor out from the maf to aid in the 2 bar. Will these injectors IFR tables at least get me close even though they are modified?

[joecar]

The IFR table will have to be rescaled for the new flowrate and for rail pressure.

[Chuck L.]

1050FW/@ a loss of 20% driveline, should put the RW at 840.
Using a BSFC of .6, and a DC max of .85, I see needing an injector with a flow rate of 93#/hr.
The Siemens 80#, [Fl114992] inj, run at 58psi should do the job, and not have to be modified.[92.4#/hr]
If run @ 61.4psi should get 95#.
A good flow number on the intake/heads, could get the BSFC down a bit, and help w/ a flow cushion..
Right/wrong????

[joecar]

Good analysis.

Would BSFC .6 be typical for boosted application...?

[exploder]

The reason we chose these injectors over the 80lbers is they are not offered in the short style. With these injectors we will not have to fab spacers for the fuel rails and have to find the correct o rings to adapt them as well.

The supercharger did arrive today as planned and I am going to start installing it tommorow. I will most likely be done either this weekend or early next week. Any more help on the ifr tables would be appreciated.

[joecar]

If the LS9 injectors have been modified, then you will need to know the new measured flowrate...

you will need to recompute B4001 to rescale for the new flowrate and the intended/measured rail pressure...

modifying the injector may alter its other "characteristics", but probably not very much... the other injector tables (B3701, B4002, B4003, B4005) should be sufficiently close enough to use with the modified injectors... (...and you have no other tables/values).

[Chuck L.]

Good analysis.

Would BSFC .6 be typical for boosted application...?

that's what I usually use. If the engine has really good VE, then that number could be lower.
Some use even higher, like .62 for FI, .5 for NA. We all wish we could get down to NASCAR area.. Maybe <.4 !:hihi:
Maybe, someone that's doing some dyno testing could post some BSFC's they are seeing w/ really hi flow systems??

[Redline Motorsports]

I just laid down 855 RWHP and 840 RWFT with 63.5#'s with a boost regulated fuel system at 1:1 ratio.

That was on 12 psig of boost. Lambda was a solid .78-.80 and I still have more room for more.

Howard

[exploder]

I guess what your saying is you have a similarly setup car and those are the numbers you laid out. Great numbers for sure. I hope we are that lucky.

[exploder]

OK.....

I got the supercharger on and everything running pretty good with the stock injectors. I installed the new 80lb LS9 injectors this morning and my day has gotten a whole lot worse. I can't get these things to idle anywhere near 14.7ish. The best I have gotten it to idle is 12.2ish. I have tried upping the ifr table 20% and lowering it 20%. I then tried to decrease the ve tables by as much as 40% and I still have not gotten anywhere close. I used the marcintechnology IFR calculator and input the info from the injector flow paper that came with them. I then used the conversion chart that joecar was nice enough to do the legwork on and filled in the small pulse and other transient tables based on what the STOCK ls9 injectors show. What is my next step? Here is a tune file of what we are working with.

I also got a tune from andy at A&A corvette that is running these identical injectors and has them running smoothly however he is using hptuners and is also tuning on a c6 vette not a c5. Here is his tune file for comparison as well. I don't know how to extrapolate between the two files.

[joecar]

Exploder,

Is FPR un-referenced or manifold-referenced...?

What is your measured running rail pressure (remove reference hose if FPR is referenced)...?

What is the flowrate of the injectors...?

[exploder]

The car is boost referenced. The FPR is set to 58psi with the vacuum line plugged in. The injectors are rated at 80.5 at 43.5. Anything else you may want to know? I can adjust rail pressure wherever you guys say it should be.

[joecar]

Measure and set the rail pressure with the reference hose unplugged... set it to 58 psi.

Then when done setting it, remember to reconnect the hose.

[joecar]

With rail pressure set to 58 psi (measured with reference hose unplugged), this is the IFR:

ifr = 80.5[lb/hr] * sqrt(58[psi]/43.5[psi]) = 92.9534[lb/hr] = 11.7119[g/s]

Set B4001 to this value all across (flat static since FPR is manifold-referenced).

[joecar]

We assumed you had the returnless/unreferenced FPR... we should have asked you about this right from the start, sorry about that... :doh2:

[exploder]

Ok I'm going to go change FPR right now and change the IFR and go try this. Cross your fingers for me.

[joecar]

Since these are modified LS9 injectors, use the other tables from the LS9->LS1 spreadsheets...

but use the value from post #20 for B4001 (same value all cells)... but be sure to set FPR rail pressure to 58 psi with reference hose removed...

i.e. FPR has to be exposed to baro during measurement.

[joecar]

Don't forget to re-connect the reference hose to the FPR when finished measuring FPR pressure.

[joecar]

I gotta run now, I'll catch up in an hour or two... :)

[joecar]

Oh, you will also have to redo the VE table now...

[exploder]

NO GO.....I set rail pressure at 58 with vacuuum off while running and then reconnected it and it dropped rail pressure to 50ish. I then loaded the tune with the IFR of 92.9534 across the board and it still idles around 11.8-12.2. I am really losing my patience at this point so I reduce the entire VE table by 40% and it is still idling in the same area. I'm lost as to what to do unless I just swap injectors. Please help.

[exploder]

Here is a log with injector duty cycle. It shows they are only around 3%. I also have a set of 72lb injectors here I can try later if anyone has an IFR table and everything else for those......

[exploder]

I just went back and looked at the log and it shows that my commanded AFR is 11.3....how did that happen? Where in my tune would it make it do that?

[joecar]

NO GO.....I set rail pressure at 58 with vacuuum off while running and then reconnected it and it dropped rail pressure to 50ish. I then loaded the tune with the IFR of 92.9534 across the board and it still idles around 11.8-12.2. I am really losing my patience at this point so I reduce the entire VE table by 40% and it is still idling in the same area. I'm lost as to what to do unless I just swap injectors. Please help.This is ok, it is supposed to do this.

This is correct also.

Are you in SD mode...? VE will have to be re-done for the new IFR.

[exploder]

Holy crapola....you will never believe this. I looked at the log again and the commanded AF was 11.6 and map was at 13.9.....I went and checked the map and found it had come unplugged I guess when I swapped the injectors. I had to go back and play with the VE alot but I got it running correctly now. I will make some logs tonight and report back.

[joecar]

I just went back and looked at the log and it shows that my commanded AFR is 11.3....how did that happen? Where in my tune would it make it do that?Your log in post #28 shows that MAP is pegged at 96kPa... looks like MAP sensor is open to baro.

Your tune file in post #16, B3647 has 95-100kPa cells set to EQR 1.244-1.299 (AFR 11.3-11.8)... MAP is pegged at 96kPa, so this is the AFR you see.

I see by DTC P0102 you're in SD... so do this:
- fix MAP sensor,
- re-do VE table.

[joecar]

I also see B3616 set to 0% from 0-1200 rpm, set this back up to 64%.

Set B3618 from 0-2400 rpm to the same EQR as the rest of that table.

[exploder]

I did a good bit of driving today and got it semi close to where it needs to be. Tommorow when the roads are dry I'm going to slowly start rolling into boost and I hope all goes well. If anyone has any suggestions for any extra transient filters for my logs would be appreciated. Here is a log and a tune for where I am at as of now. I went in and hand smoothed.

[joecar]

That looks much better, good job...:cheers:

Note that B5917 is set to 256, which means that the base spark table is used when actual throttle position goes under B5916
(I see minimum TP is 11-12%... if this has ETC then need to log the other throttle position pid).

Also, every so often, at steady throttle/airmass, there is a sharp down-spike in spark timing... I'm not able to see what's pulling it.

[joecar]

Don't forget to make the 105kPa columns in B0101 and A0009 the same.

Try injector tables B4003, B4005, B3701 from the LS9->LS1 spreadsheets
(in each spreadsheet, the second table pastes-with-labels into the LS1 table).

[exploder]

I had already gone back and made the 105kpa colums the same. I am also going back to change the injector tables. The car is a ETC vehicle, but what other TP pid are you talking about? Do you mean I need to not use the pid that is selected or I need to have another TP pid in addition to the one I'm using. Also B5917 is set that way from the factory I guess on most corvettes because I went back and checked several other tunes I had and they are all the same. What do you suggest changing b5917 to. I think the sharp down spike in timing may be the boost timing table kicking in as I had it set to pull 10 degrees. Keep the advice coming.

[joecar]

Those injector "characteristics" tables may help with pulsewidth at idle and during throttle transitions.

I think the pid is GM.APP.

B5917 might be ok, because both B5917 and B5916 have to be met for the PCM to revert to the base timing table, and B5916 is set low.

Ah, I see, boost timing table, ok, I'll take a closer look (a bit later tonite).

[exploder]

I did some more logging tonight and everything is going fairly well. I finally rolled into boost and found out my fuel pressure is dropping. I have it set up with a secondary fuel pump to kick in under boost. I'm going to test my boost pressure switch tommorow to see if it is functioning. I also had the dreaded 1514 code and went into reduced engine power under boost. I went back and decreased the VE, IFR and Boost VE by 30% and that seemed to fix that problem. I do have 3 issues I need to resolve.

1. At highway speed while cruising in 6th gear if I need to slow down every once in a while as I take it out of gear and go to neutral while rolling it just dies. I can crank it back up no problem though. What do I need to tweak here?

2. When I am in 6th gear and logging in the scanner at steady speed and I hit the 1600rpm and 80kpa and over cells it starts commanding an AF of around 12.5ish and it runs like crap there and it obviously needs to be around 14.6 or so at that low of TP%. I have to go back after each log and remove fuel manually in these areas to keep it where it needs to be so that it runs correctly. How do I exclude or lessen the effects of this because B3647 is commanding it to be there?

3. I have a small stumble as I take off from a stop. I looked at the log and it was pulling alot of timing with no knock right as I would let out of the clutch and get rolling. I added some timing in the areas and it drove better, but now it has a bucking to it as I get moving at low speeds. I can give it more gas and it will pull through it or I can push in the clutch and it will stop.