tunning for bigger injectors

[gigabrock]

hey alright i would gladly pay you if you could teach me how to do this cause I'm just about to give up hope because i can't figure this out at all and I'm afraid I'm gonna screw my truck up cause the tune i have now doesn't seem like its up to snuff its just about good for smoke and thats it and i graduated with your brother in 09

[THEFERMANATOR]

Check your email, I just sent you a tune to try out. If it works I can up it a bit for you if needs be, but this will give a baseline as to wether or not the 40 over tunes I have will work with your 30 over sticks.

[gigabrock]

thank you sir i really appreciate it and what do i need to look for to see if it will work like i said I'm extremely new to this and really don't even get the concept of logging and how to read them and how to adjust and the logs i have been doing I'm not even sure what to monitor and what they should be

[DirtyMax03]

Small world. Yeah, EFI Live has a steep learning curve. I have been using it for 3 years and still learn new things every day. If you are free during a weekend later in October or November you could come by my shop and I could give you a quick tutorial on EFI Live and help you with your tuning.

Give THEFERMANATORs tune a try as it sounds like it should be better than the tune that you are currently running if the tune you are currently running is excessively smokey. I too am learning the tricks of tuning for bigger injectors on a local customer's truck with 30% over nozzles.

THEFERMANATOR,

I would be interested in taking a look at your 40 over tune just to see how it compares to my 30 over 'tranny safe' tune. I basically dialed back the fueling 25% at max fueling and gradually stepped down the amount of decreased fueling as rail pressure decreases. I then use a modified timing calculator that I have found works best for economy at light loads and power at full load to set the timing. Decreasing the PW and using the spreadsheet calculator effectively dials back the timing for the bigger sticks.
It may also be helpful for you to know that 30% over nozzles actually only deliver 22-25% more fueling at rated pressure when the nozzles are installed on the injector. I work with a guy from Bosch and he was explaining this to me.

[DirtyMax03]

Mind you the 'adjustments' I refer to above are changes made to my 125HP single tune and not to a stock calibration. I also learned from the Bosch guy that bigger sticks also open slower especially at lower pressures so you don't need to take out as much timing in the cruising range as you might think for the bigger sticks. I think he was referring more to 100% over sticks, so this phenomena may not be as pronounced on 30% sticks, just fyi for anyone that is interested.

[THEFERMANATOR]

Try the tune out and see how it responds in your truck. If it seems to run good then we can log it and set it up where you need it to be at. As far as changes go, they have to made to account for injector latency. Changes across teh board will net you poor results, you need to find your lag time and subtract that fro myour pulse time, then make your changes, and then add the lag time back in to get a better pulse table adjusted for the different injector size. And also keep in mind that even though you went up 30% in injector size, that doesn't always equal out to a 30% reduction in pulse time to make it back to stock. The percentage will vary across the board, so it is best to start small and work your way down to what you need. The 40 over tune I have is only dialed back down 15% in the idle areas, and it reads right at 8-9MM3 of fuel at idle where a stock tune would. But higher up you have to increase your percentage to get the flow equal. And I normally don't share the tune file I have as I have ALOT of time tied up in it, and it was somebody elses tune file to start with.

[DirtyMax03]

FERM,

Yep, injector latency is what I was referring to with the delay with larger injectors, also called injector energizing time. I am familiar with the phenomena but not familiar with how to mathematically quantify the additional lag time without injector test data. Do you have a way to determine this using the PIDs provided with EFI Live?

Same with injector flow, without injector flow data all you can do is do like you said and back down the PW slightly down low and back out PW progressively more as rail pressure increases. But if you have a more mathematical method I would love to discuss it with you as I hate 'stabbing in the dark'.

I totally understand not wanting to share the cal as I know you have TONS of time invested in it. If I didn't enjoy dabbling with this, there is no way that I could make a financial business case to justify the hours I have spent playing with EFI Live.

[gigabrock]

ok thanks i am waiting for my computer to charge and then i will go out and try it i was gonna try it during classes but my computer died during my horticulture class so i didnt get to it but i dont mean to sound dumb but its going to sound dumb when i ask this question when you say see how it runs what am i looking for and what do i need to watch out for listen for and what pids should in your opinion should i have pulled up in the scan tool when i try it by the way thankyou very much for helping me out it means alot and dirtymax03 just let me know when you are availible and would like me to come there when its good for you because i have two jobs and i have to plan in advance when doing something so whenever is good for you i can come just gotta get it okayed and i will prolly just come there for the weekend and take the little lady shopping or something while im there i dont really get to get out of vincennes much so any excuse is a good one especially if its to learn something

[THEFERMANATOR]

The PIDS to watch would be fuel rate as you want to see what the idle fuel rate is(should be 8-10 MM3 of fuel at a hot idle). make sure it runs smoothly, and that it isn't smoking white. If the injector flow rate is off to much, it will blow out white smoke fro mthe low fuel rate and off pilot injection. If it runs and performs well, monitor fuel rail pressure under a WOT run and see how much it is holding. If the tune runs smoothly and performs well, then you can use rail pressure to help dial in how much pulsewidth you can give it on the big end.

For injector latency, i have found 100 USEC to be a good number to use across the board. I came up with this number by trying out minimum injector amounts in a tune file, and find at what point pilot would be basically useless. I found that at roughly 105 usec the pilot pulse became pointless, so I use 100 usec as my latency amount. Subtract it from the whole table, and then make my % reduction. For the 40 over sticks I did, I found that 15% in the 0-10MM3 of fuel areas actually brought it back REALLY close to stock idle fuel rates. And used 20%$ from 20MM3 of fuel on up and it brought it back to stock performance. Every injector set is different though as the base file I used was set up with the same size sticks fro manother shop, and it used almost 25% across the board. Yet both trucks held almost identical rail pressures at a 2500 pulsewidth on the big end. There is no ryme or reason to how much to reduce it and where, just have to play with it accordingly to each set.

[gigabrock]

ok so i got it on the truck and it seems to like it it idles smooth and isnt noisy at all i didnt hear a knock or anything of the sort but i did have one little issue if i rev out to above 2500 or so rpms and i push the clutch in to shift it seems to hang that rpm for a second or two and the next thing was it seems like it has trouble getting the truck going when starting from a dead stop it almost seems like it has very little power at lower rpms but when i get higher in the rpms and pop on the highway it seems to do very well but like the power addict i am it just seems a little sluggish but i drove 30 miles in town and on highway and those were the only things i saw and my last tune i had seem to have a natural lope when i first started it when it was cold and this tune did no such thing