Hey guys, I've got a mostly stock L98 with shorties/exhaust and a ZZ4 cam.

Running ARAP $6E right now. For some reason my idle is always 108BLM at about 10gms/sec. The wideband reads about 12.5:1 in open loop at idle.

The problem is that when I lower the MAF table values (ive gone all the way down to MAF Table 1 being a flat line at 5gms/sec) it still reads 8-10gms/sec and runs 108BLM.

Any thoughts?

 

Maybe you having some fuelling problem, like an bad FPR or fuelpump. Maybe leaky injectors and thats why it isnt getting any better when changing in the PROM. have you checked your injectors and fuel pressure ?

 

The injectors are Ford SVO 24#, with a Holley AFPR. I have the fuel pressure set at around 47psi. The fuel pump is good.

The wideband reads a perfect 14.7:1 once closed loop hits, and has BLM of 108. Even when the appropriate MAF table entry is lowered dramatically, the BLM stays 108 and still runs 14.7:1

 

The Ford injectors are set to 39.15 PSI pressure if you running 47 you get these lbs/hr out of them instead.

47psi / 39.15psi * 24lbs = 28,81 LBS / HR so thats why you running rich...
You need to set your injector constant to ~28,81 and then it will run good again..

The Ford injectors are made to run 39.15PSI pressure, so with 47PSI they will flow much more then it says...

 

24lbs @ 39.15 psi ---> 26,3lbs @ 47psi

 

I'd bet that the Minimum Allowable BLM set in the PROM is 108.

Take a look at the AFPR. My Holley AFPR leaked fuel through to the vacuum side of the diaphragm and into the plenum.

If you remove the vacuum line from the AFPR while the engine is running and it is leaking fuel out the port that's it.

 

How do you calculate that ? You did calculate only during idle ?
But then He would be WAY rich during part throttle and WOT...
43 psi / 39.15 * 24 you get 26,36lbs.. Is that what you did ?!


They flow 24 lbs at 39.15 PSI pressure..
If he runs 47psi you take 47/39,15 * 24 = 28,81lbs /hr will they flow at 47 PSI...


You must still be very RICH at WOT and part throttle right ?! Do you have any logfiles you could upload ?!

 

The problem in this case I think is the injector constant in the prom
If he runs a higher pressure then 39.15 PSI the injectors will flow more then 24lbs as explained in earlier posts..

If he try setting the new injector constant and log again we will prolly see a much better BLM.

 

The injector constant since the start has been set to 27.

hrmm

 

Try 28,81 inj. constant.
And see how it runs then..

 

Check your min pw and default pw and adjust accordingly. I suspect your running into the limit.

From ARAP:

;==============================================
; FUEL OUTPUT PARAM'S
; calib = msec * 65.536
;
;==============================================
LC3AB: FDB 0104 ; 1.580 msec Min Base PW
LC3AD: FDB 0104 ; 1.580 msec Default Pulse Width

 

there is also programs on the web,

http://www.rceng.com/technical.aspx

http://www.csgnetwork.com/fiflowcalc.html

 

Also watch your injector pulse width my car runs at the 160 even though the plugs are black and the pulse width is 3 ms at idle (way rich).

The "proper" ms at idle is around 2 ms (for my setup) so the O2 is off. The NB one wire and the heated NB read the same,heated was "better", (tried more than one) found a small exhaust leak at the flange. Exhaust out, air in = 160 BLM. I will try two more heated NB before I will pass judgment as to what is "OFF".

 

From the Calibration Sheet SVO 24#

Target Injection Pressure = 39.15 psid

MINPW (ms) 1.053

VBAT ........Voltage Offset
(volts)........... (ms)
6................. 3.388
8................. 1.755
10................ 1.122
11................ 0.928
12................ 0.781
13................ 0.659
14................ 0.547
15................ 0.462

If you want your injectors to be linear, I would start with these numbers.

 

opps

 

Are these Injector PW Correction -vs- Battery Voltage numbers?

 

Yes, straight from the injector calibration sheet. This needs to be done when upgrading to the SVO 24#. If you don't upgrade the software numbers, when you upgrade the hardware, you don't get all the benefits of the swap.

 

How do I go about creating a new XDF item for this in TP?

Thanks, I put those values into the PW correction vs Voltage table.

 

How do I go about creating a new XDF item for this in TP?

Open TP,
Right click on, the last XDF item in the constants/scalars window.
Left click on, insert new item.
Under the general tab, title "min IBPW" description "MINIMUM INJECTOR BASE PULSE WIDTH" units "ms" address (hex) "3AC" size "8 bit"
Under conversion "x/65.536" use the edit.
Hit the apply tab, to save.
Hit the close tab.
Double left click, new XDF item, to read the value (1.59 oem)

 

Where can I get the PW Correction -vs- Battery Voltage chart for 22 lb. (pink top) SVO's?

 

Im getting new Ford 19lbs injectors to this week, So I need to change my battery vs ms to then ?! I just use this info in this pdf to make it work then !? : http://www.fordracingparts.com/parts...-9593-c302.pdf

The table : FNPW_OFFSET (in the PDF is that what I should put in my PROM)

VBAT..........VOFFSET
(volts)............(ms)
6...............3.548
8...............1.863
10.............1.221
11.............1.026
12.............0.867
13.............0.741
14.............0.647
15.............0.552


And also I need to change the injector constant, because the FORD injectors are set to 39.15 PSI pressure, and Im running around ~44PSI
So then I need to take 44 / 39.15 * 19 = 21,35
So I need to change the Injector Constant to : 21,35 also to compensate for the higher fuelpressure..

Is that correct now ?

Or is the correct Injector Constant : 20.14 (this is when I used this calculator : http://www.csgnetwork.com/fiflowcalc.html)

Enter Original Fuel Pressure : 39.15
Enter New Fuel Pressure : 44
Enter Rating Of Fuel Injector (lb/hr) : 19



EDIT:

Looked at my ANYH prom now. The battery voltage isnt exactly the same :
Whis is how the Injector Pulse Width Correction vs. Battery Voltage looks like
Dont have any other to change with battery voltage.. using $6E ANYH prom.

VDC........usec added
25,6........0.00
24,0........0.00
22,4........0.00
20,8........0.00
19,2........0.00
17,6........152.59
16,0........305.18
14,4........488.29
12,8........701.91
11,2........1037.61
9,6.........1434.35
8,0.........2197.30
6,4.........5340.65
4,8.........1007.09
3,2.........1007.09
1,6.........1007.09
0,0.........640.88

 

I believe that if you'll look at the Fuel Injector Constants in the PROM you'll see that they are listed as at 40psi.

 

But how about the Injector Pulse Width Correction vs. Battery Voltage then !?


mnorton:

How do I calculate the correct injector constant for the 19lbs ford injectors then, My fuelpressure is ~45PSI (without vacuum)

 

Like I wrote.....
You could also look in the Fordmotorsport *.pdf catalog page 135

PW vs battery, In most cases I dont think its necessary, on most car I have tuned I didnt have to change it, I still managed to get a good Idle, maybe it could be better....If I played with the table..

You can (fine) tune forever if you want. Thats the downside of having a laptop in your car and prom equpment, there is always something you want to try and so on.

On my car I modified the table some because of my 70lbs injectors.

Ps this is a good thread to read for the beginners https://www.thirdgen.org/forums/diy-...-i-wish-i.html

 

If you haven't seen this video you should watch it. I have the pink top 22lb. SVO's in my car.

http://youtube.com/watch?v=Emnax2J4FX4

 

FNPW_OFFCOMP
39.15 1.0000
44.95 1.0673

At 45# FP multiply 19# * 1.0673 = 20.28#, which is the "new" #/hr, that the "19# @ 39.15 FP injector" will flow, at 44.95# FP

This is a "measured value, from testing", not a "math value, from theory" estimating the change in flow at the higher pressure. The math does not, "calculate the opening and closing characteristics". The math works better at steady state,saturated type, flows.

Injectors can be non linear by design.

Injectors that are flow matched are not calibrated, they are all off the same amount. That could be 19.25# or 18.75 #.

When the injector constant, in the eprom, is set, it is the "best guess" at what the injectors are "really/actually" flowing.

This is then compared to the O2 "average" reading of four "injectors/cylinders", this "blm/injector constant" is then adjusted using the O2 as "god" as to the reading being "right" for all eight injectors (closed loop). This can also be manually changed as to center the adjusting range (128 blm).

As to the IPW Correction vs battery volts, you need to find the in between values to match the ECM/eprom listed Volts. This table is calibrated to the injector not anything else, different injectors will have different tables.

This table is used to "fix" other rich/lean issues, but that is better done in the "correct" area.

You can steer left to offset a right pulling car but fixing the "true" problem is better, it just takes more "time and understanding".

 

Thanks for your help guys. With the minimum pulsewidth changed Im able to see some results. Im going to have to drop my fuel pressure to get to a 128 idle.

 

Thanks, then I try setting my injector constant to : 20.28# and make some datalogs and runs and see how it turns out

Will also see if its necessary to change the injector pulse width vs battery voltage to...

 

Yeah but as you know I having problems with my idle.
Havent checked the fordmotorsports catalog but Ive checked the injectors catalog linked to above...

Yeah I know I can fine tune forever, thats the worst thing, When I get it running smooth I will not do any logs for a loooong time to avoid making any more changes...

Did get the correct injector constant number from pandin..
I tried calculating using the page you linked to but it didnt get exactly the same lbs/hr that pandin showed in the document..

Thanks for all your helps guys.. Hopefully I get the gaskets tomorrow and I can start changing everything..

Will keep you all posted about this. (maybe ill start a new thread or is it OK to borrow this one ?!)

 

It's my understanding that SVO injectors are actually "flow rated" at 43.5 psi. The ford fuel rails run ~39 psi & chevy's are ~44 psi.

The PROM table in a 1989 car wants the adjusted flow rating at 40 psi. In my car (1987 LB9) the entry was shown as 20.8 psig.

My 22# pink top SVO's "flow tested" in the following video link at 22#/hr. at 43.5 psi which in my mind helps verifiy that advertised 22#/hr. flow rating.

http://youtube.com/watch?v=Emnax2J4FX4

 

As you see in this document : http://www.fordracingparts.com/parts...-9593-c302.pdf
You see that they flow 19lbs at 39.15psi pressure

because if I leave the injector constant at 19.49lbs/hr as stock in my prom it will give black smoke at WOT I know that because Ward have the same injectors and he is running rich in some places, So the injector constant need to e change, as for the IPW may too if it idles bad..

 

Here is another "Injector specific" table that adds time to improve fueling at idle
"Low Inj Pulse Width Offset vs Base Pulse Width" or "Inj Offset for Small PW's vs Base PW"


Location 3C6 $6E ARAP.

Notice that it starts to add more, pulse width time (.015 ms), at the IBPW of 2.197 ms and just keeps increasing added time till, it is at very small .488 ms (below set min IBPW).

This is where I am going to add/subtract fuel for idle.

These type of overrides, are what inhibit output changes, that would be expected from changing other, more global type of constants. If you have "hit a wall" on your changes, this is one type of wall.

After changing the type of injector, all this type of "fudges/offsets" might need to be changed to "improve" the normal operating characteristics of the hardware.

Offsets are a way to realign the "math model" with the "real world"

All of these "constants" are only a "best guess" at the real world, and every bodies "real world" will be different, because no two things in this world are ever "exactly the same"

 

The difference is lost because, first the measured difference from factory spec sheet is only .5 # per hr (for the 4.5# FP difference) and second the utube is not flowing, 87 or 91 unleaded, it is a nonflammable fluid that is close and the flow bench estimates the "equivalent" flow in unleaded.

The factory gm injectors are 22# but the memcals are set at, 23.04# bua $32 (vette), 23.04 ABTB $32B (callaway twin turbo), 23.04 AKXZ $32B (Trans Am).

Thses are dumps of OEM memcals pulled from their matching cars.

It makes one wonder why??

 

So if the fuel rail runs 44psi, why does the PROM want to know flow rate at 40psi? And how does that effect the value you put in for a 24lb@39.15psig injector?

 

The 40# in the XDF is for information only. Your guess is as good as mine as to where the 40# number came from. You can change it to what ever you want to look at. I just deleted it and will follow the real world answer from the tune and the car.

 

Hi changed my injectors today, to Ford EV1 19lbs injectors.
Changed the o-rings to, used GM o-ring to be 100% sure for no leak..

Install went pretty smooth (and I fixed the throttlebody for you guys that read about that.)
Now to the problem, Made 2 PROMs, one with the stock code nothing changed and one with injector constant changed to 20.28 (because my fuelpressure is 44psi (without vacuum) and the ford injectors are rated at 39.15.)

I got ALOT of knock retard when driving why is that so.. cannot hear any sound or anything just the engine working , no mechanical sound or anything, nice steady rpm..

PROM one is my stock ANYH code with Injector Constant : 19.48 (thats my totally stock prom)
logfile from that prom you got here : http://theking.joakimweb.se/z28/tech...uni08-ANYH.rar

and heres the second logg with that PROM/CHIP its only idle and some driving when I park it, alot of knock retard when giving throttle at idle... WHY !?

Password : irocztts

And heres a sound clip how it sounded when I tried to start it. REALLY hard to start it now, why !? Clip one, started pretty good, clip to really hard to start.... why !? Its a brand new starter, that are schimmed and installed correctly (have tested 3 starters, and this on is brand new 1 month old and it works, so it cannot be the starter) New distributor, tried another pickup and ignition module, its the same...

soundclip 1 : http://www.alandsbrodata.ymex.net/sound/start1.wav

soundclip 2 : http://www.alandsbrodata.ymex.net/sound/start2.wav

soundclip 3 : http://www.alandsbrodata.ymex.net/sound/start3.wav


and heres the BIN file for that logfile, soundfile and info : http://theking.joakimweb.se/z28/rep/bin/ANYH.bin

---------------------------------------------------------------------------------------

And heres a logfile from the second prom ANYH_20 : http://theking.joakimweb.se/z28/tech...i08-ANYH20.rar

Password : irocztts

very lean, thats because the injector constant is set to 20.28 (to compensate for the flowrate of the ford injectors, but that didnt be right...)



Will make an 3rd prom from ANYH and make the injector constant to 19 and see if it runs litte better, seems lean on some places in the first 2 logs...


Please guys, help me out, any ideas what could be wrong here ? Why is it so hard to start now ? and why is it shaking and wandering so much on idle when I got D in and holding Brake at stoplights ?! sometimes it really "misses" and the hole car shakes alot, and then the rpm gets little higher, and after some seconds its missing again and so on and on..

and this is how the plenum looked inside :





also here you got an video file on how the RPM jumps around when it "misses/not burning right" its hard to explain but the car almost like it choking it self on some rotations.. the rpm drops 100rpm or more and the car kinda "wakes" up and it shakes alot when this happens... as said its hard to explain how it pretends, but you see the rpm needle and maybe hear how it runs ?!

movie : http://theking.joakimweb.se/problems...rocstumble.mpg

Its worst when I have a gear in and holding the brake at stoplights and so, not as much shaking when just idling in P its still there but not as severe..

Please again help me friends


also I made an new thread about this here : https://www.thirdgen.org/forums/tpi/...ml#post3797022