Thread: Creeping afr and timing issue

Did you read the guide? I wouldn't touch them until you have an idea what direction you want to tune. You need data from scans first.

leave the neg part along is my guess.

you make a grid on paper mark down 10 through 100 to represent the kpa in the injectors flow rate.

now look over your scan and look at what your maf kpa cell is and then note the ltft when in each kpa cell. ( 10 -100) lets say its -12 at 30 kpa. you would subtract 12 from that number in the injectors in kpa cell 30.

if it was +!2 you would add 12 to that number as per the kpa like above noted. once again. dont go the full number.

i will say i tried the full number's and over shot it the first time. go 3/4's the way. let the trims learn and re scan.

all this is in the manual i sent you in the webracing part of the manual.

Originally Posted by gambler87

I have scan data and the guide only says and shows map kpa from 0 to 100. My ECU for my 04 shows negative values as well. It says to just make anything less than what ur cars sees the same number as the lowest one. So I did, I just didn't know why it shows negative kpa

I wasn't sure what you were asking. I haven't seen an IFR table like yours. My guess is yours is showing compensation for when you are in boost, by the negative numbers. Only guessing, but makes sense since you would need a little more fuel flow to counter the positive pressure. I kinda wondered why the tables I looked at didn't have boost compensation shown.

Side note, and it may be wrong but just something I read while tuning my injectors. You will notice some cars have the same value in all cells, while some are decreases as vacuum increases. I read that this was somthing that GM did to compensate for the crap fuel pump wiring. I believe the 97 gtp had the same values in all cells. But there was an issue with cars going lean as you left vacuum because of inadequate wiring to the pumps. To fix this the IFR was changed to the increasing values you see in later years. Technically I think the fpr should maintain the proper fuel flow no matter what, but the stock wiring is just too weak to provide the pump enough power during heavy demands. So, bla bla with my noob ramblings, but anyways I set my IFR table all to the same single value which I calculated for my 60lb injectors, and have had no issues. I actually had much better results at WOT, where my commanded and actual A/F matched much closer than before. Edit: And I've done the rewire.

^^ I'm still not understanding that. My thinking was the lower the number, the less fuel that is flowing. So like when you put larger injectors in, you decrease the numbers by, say, 35%. That way at a given kpa you will decrease the time the injector is open to allow the same amount of fuel through the larger injector as you had through the smaller injector. Am I seeing this backwards, Rep? Sounds like what you are saying is the larger the number the less fuel is exiting the injector?

Originally Posted by gambler87

My car only sees down to 50 kpa. So anything under 50 should be the same flow rate as 50, correct?

Yeah. If you've done the fuel pump rewire you can safely make all the numbers the same too, calculated for your injector size. Here's an earlier reply I made on this to someone else. Its how I did it. Not saying its the only way, or even the best way but it worked well for me:



So I used HPTuner editor, which shows my stock injectors in lb/hr. My stockers were 21.5. I found that the Siemens Deka 60's I have flow 60lb/hr at 3bar. Our fuel system runs at 3.5bar. You can use the editor in HPTuner to calculate what the injectors will flow at 3.5 bar/50.76 psi. Go to tools-unit conversion. There at the bottom right is where you can enter the injector size, then what pressure it is spec'd at. Then enter in your current fuel pressure, and it will give you the injector size to enter in the IFR table.

Of course HPT and dhp reads this different. So what I did is take my stock 21.5 and divided that with the value I got in the unit conversion which was 64.81. That gave me .33. So I went back to dhp and multiplied my stock IFR by 33 percent. Saved it and opened the tune again in HPT because I was shooting for 64.81. Wasn't exact so I made small adjustments in dhp until I had exactly 64.8 in HPT.

Not sure what size injectors you run, but different just plug in your specs. At leaast this will get your IFR table dialed in, and you won't be trying to tune around it. Up to you whether you skew the IFR, but I'm gonna leave it flat because I think with rewire and my Aeromotive pump there is not really a reason to have it skewed. Probably explains why my A/F is so rich during WOT when i'm commanding it much leaner.

See and that's why I also like HPT But I don't have a license for it, so can't save anything, but I can use all the software tools and get the values, then just convert over to dhp. Little more work but I get the best of both worlds

Yeah I envy those Histograms. I've gotten pretty used to using uvscan though, and you can do some cool things with the data in excel, just more work.

Don't forget Tiny Tuner It allows more tweakage than both dhp and hpt. I used it to make some fine adjustments to the injectors, as well as it being the only program you can use to turn the boost solenoid on if doing a top swap.

TT can also kill off the cat test in the 01 up cars

Why?

Ah OK. Thought maybe you had a bad experience with it or something.