what tuning needs to be done to use 42# injectors

Alright guys I have a 96, and just got new 42 injectors and am using)
Pt to tune, I know you add .847 to each injector. On the96 it does it by all injectors so..

Do I just multiply .847 by 6 which is 5.082 and add that to my existing value , which is currently 207.17 msec/gram, ..

That would give me a total of 213.252 ..

Right or wrong

I thought the IFR values went down when going w/ larger injectors. So multiply your 207.17 flow rate by .847 (for 42.5 lb/hr injectors) = 175.47 g/msec. Wait for someone else to confirm, as I'm not 100% sure about the '96.

I think your right, bigger injectors flow more fuel so you would lower it..I'm still going to wait for a response from someone that knows for sure...thanks

What AA said sounds right. I still have my DHP bin file but not the software. I'm downloading and will confirm for you ASAP.

Ahhh now I remember why I don't have DHP software anymore. I can't run .NET 1.2 on my current build. If you want my .bin file I'll email it to you, PM me with your address.

Pm sent.. I think.

turtleman wrote:

HPTuners
That's my table

See if I can test your memory...

Why do you have the values the same across the table and not ramped?

Just curious. Starting to dig into injector table stuff. Does anyone else smell corn in the air?

Have we confirmed that you simply multiply the IFR table by the percentage difference between stock and whatever injector poundage you are switching to?

If the stock values weren't ramped, why would you ramp them with bigger injectors?

AA wrote:

If the stock values weren't ramped, why would you ramp them with bigger injectors?

O..? Do your stock values look the same? Cody's snapshot is a stock table?

Mine are ramped from 37.468@0 to 38.415@100

Mine are basically flat, sloping slightly in the opposite direction:

kPa 00 = 37.95 g/sec
kPa 10 = 37.51 g/sec
kPa 20 = 37.00 g/sec
kPa 30 = 36.17 g/sec
kPa 40 = 36.00 g/sec
kPa 50 = 36.00 g/sec
kPa 60 = 36.00 g/sec
kPa 70 = 36.00 g/sec
kPa 80 = 36.00 g/sec
kPa 90 = 35.67 g/sec
kPa 100 = 35.50 g/sec

Stock values, according to DHP:

kPa 00 = 35.16 g/sec
kPa 10 = 35.06 g/sec
kPa 20 = 34.99 g/sec
kPa 30 = 34.89 g/sec
kPa 40 = 34.75 g/sec
kPa 50 = 34.68 g/sec
kPa 60 = 34.63 g/sec
kPa 70 = 34.58 g/sec
kPa 80 = 34.54 g/sec
kPa 90 = 34.42 g/sec
kPa 100 = 34.31 g/sec

interesting , my IFR values are also ramped like charlies. im starting to get curious about the little differences in the tune. I might compare my sisters Riviera to mine, to see what differences I can find.

'96 and '97 Rivs have a flat Injector table. '98-'99 have ramped tables from the factory. I remember seeing this when we initially did SirPsychos ride. I opened up his file and went huh? My '97 is also the same way....flat. I'm not sure if they did this for fuel economy or what, but they did it...

Interesting. Good info to know! (+)

I've noticed a slight need to ramp the tables to get the O2s where they need to be. On the stock tables my O2s would be in the mid-high 800s and now they're in the low-mid 900s. Still need a wideband to really narrow it down but this seems to be working well.

I tuned using stock O2 values in the beginning using an AFC Mini 2.0. Wasn't exact, but the results were predictable. Got you in the general range for correct operation. It seemed the more time spent logging, the more accurate the O2 values were.

I finally figured it out! I have to use Paint on this comp.....

Here's a stock '97 FI table (on the right).


Here's a '98 table from my car (stock again on the right).

There's a theory that the table was intended to be flat but that it was later curved due to the fuel supply not keeping up perfectly at higher pressure, particularly on the lower budgeted fuel systems - w-body's, etc. Ideally that table would be flat since the fuel pressure reg handles that equilibrium.

Would I be able to run 42# injectors and 255 walbro onstock tune?

chitown_riv98 wrote:

Would I be able to run 42# injectors and 255 walbro onstock tune?

stock tune does not equal 42#ers

also, what is your IDC? do you even need bigger injectors?

Some people say if you just run E85 on 42's with a stock tune it balances out. However, you're much better off getting a tuner before hand or have somebody install and tune for them.

also I don't think that putting in a 255 lph pump in is much better than stock.
when I look at a stock pump on rock auto it says;
Minimum Free Flow Rate (gph) 55
Maximum Free Flow Rate (gph) 65
65gph equals 246 lph

kylan_13 wrote:

also I don't think that putting in a 255 lph pump in is much better than stock.
when I look at a stock pump on rock auto it says;
Minimum Free Flow Rate (gph) 55
Maximum Free Flow Rate (gph) 65
65gph equals 246 lph

That's some good info. I'm gonna verify and probably just go with ac delco then. I might just wait for the injectors until I upgrade to ported heads and 1.9 rockers or install em before my tune at zzp? Gotta pick up a tuner asap, if there's anyone near Chicago I'll pay for a tune!  I'm gonna be paypaling you hopefully by the end of the week Matt. Just picked up 22mm sts rear sway bar.

I am in Detroit Michigan. I've got HPT with unlimited 1998 Riviera tunes . so if your around I could try and help you out. or I could meet you around Kalamazoo when I go to visit my brother. let me know

o ya, if you decide to buy a tuner(which would be good if you plan to do more mods). I suggest getting the pro version of HPT, I didn't and I am kicking my self in the ass. you want the pro version so you can data log a wideband o2 sensor, plus any other 0-5volt signals.

LOL one more thing I thought of. if you want a cheap hpt, you can buy a used basic version straight from hptuners.com. they have a bunch of them because people like me exchange the basic version for the pro version when we realize we need the better version.