which ifr is right?

[SgtMarshal]

it might seem like a dumb question, but which one is better for 42.5 lb injectors? my fuel trims have been rich for the past month, and I'm trying to figure out if my ifr is the cause.

[Iceman6669]

Try the one on the left and reset the trims. See if that does any good.

[bandook]

Try the one on the left and reset the trims. See if that does any good.

I'm total noob to tuning. Can you explain why you would choose the table with higher values? My initial thought was the smaller values, since he's running rich.

Also, couldn't you lean it out by decreasing MAF table values?

[Iceman6669]

Lol. I meant the one on the right. Mis-typed

[SgtMarshal]

I loaded the one on the right, and reset the trims, and its still running rich. I'm wondering if the rich condition fouled my spark plugs, and or my o2 sensors. I have the autolite 103's in now, thinking about changing them back to the 104's to see if it makes a difference.

the race track is open tomorrow if it doesn't rain, so I'm hoping to get this figured out today and run it at the 1/8 mile. I even reset the tune to one of my very early tunes to see if there was something else in the tune that could be causing the richness. and still did the same thing.

[timboku]

How rich are you? Why don't you just adjust maf tables where you are rich? Tuning with a nstar tb was a b$#*@ for me as well...I imported 42.5 ifr, got trims within 7ish, then adjusted maf accordingly, and fine tuned with table modifier thingy...took forever but it worked out.

[SgtMarshal]

if it was only 7ish I would do that, but its around -22

[BillBoost37]

There's too many variables that you leave out if you only look at IFR.

To that point though, you can scale your injectors down by say 10% and see if that brings you into range. Maybe your fuel pressures are right on or above average and your regulator is giving you great pressure to the injectors.

[bandook]

Have you made sure you don't have a leaky injector? If you keep lowering your IFR but your trims don't change it seems plausible. Are trims always low or just at idle?

[SgtMarshal]

I changed out the injectors and the same thing happened. how much fuel pressure is too much? I tested it a few months ago and at idle it was reading like 53, which is 1 psi of the range listed in the book we were reading from.

the other thing I noticed is that the rear o2 sensor range is anywhere from 0-900, which I think it is supposed to stay under 500, but I already know its running rich, so that doesn't really help.

is there any reason the autolite 103 spark plugs could be causing the rich ltft's?

[timboku]

Possible vac leak? Do you have correct lq4 table in....that seems like a mechanical issue more than a tune..or a messed up 02 sensor..you running a cat?...when is it running rich idle, cruise, wot, all of them?

[bandook]

Spark plugs would if its misfiring.

[SgtMarshal]

it runs rich all the time. I'm pretty sure its a mechanical issue because I've changed the tune several times and runs rich with no change, although my car starts easier when the IFR is leaner. I'm thinking there is too much fuel pressure, just put in a new map with no change, thought maybe too much map pressure would cause the rich condition, but the map readings are the same from several months ago.

[Iceman6669]

what are your fuel trims under boost?

[SgtMarshal]

I tried to answer just "0", but it gave me a fail message for too few characters. short term goes to 0 and long term shows -0.78

[Iceman6669]

if your LTFTs are at 0.0 under boost then I would adjust the maf curve to get the trims back on track. I would adjust the IFR to get the LTFT back to 0.0 under boost first.

[SgtMarshal]

I tried doing a maf smoothing with the table modifier scan data thing and it didn't seem to have any effect. I have hp tuners and am about to buy some credits to start using it on my car, do I just do a maf smooth with the hp tuner, and the fuel tables look totally different between the dhp and hpt.

[SgtMarshal]

Maf adjustment does nothing, thinking the fuel pressure regulator might be bad

[bandook]

Maf adjustment does nothing, thinking the fuel pressure regulator might be bad

Have you pulled the vav off it and seen if it leaked? I've seen them take almost 2 minutes before fuel came out.

[NebTurboST5]

didnt you have this pile of bolts down to like + or -7 on your ltft's a while ago? definitely gotta get it right mechanically before you start ****ing with the computer. what was the stock value of the IFR before you started messing with the tables?

FOR ALL OF YOU CONFUSED ABOUT INJECTOR FLOW RATE VALUES...
in DHP the IFR is measured in mSec/gram that means time to shoot a certain amount of fuel. in hptuners and most general ratings for injectors they are measured in lb/hr or cc/min meaning amount of fuel delivered in a specific time...see how these are different?

that means that while 42.5 lb/hr injectors are larger then stockers, in DHP the number in the computer will actually get smaller because a bigger injector can deliver a given amount of fuel (in this case 1 gram) in less time then a smaller injector.