I posted up on HPT forum, figured I'd bring it up here too. I put in some new siemens deka 60s yesterday, doing all the tuning myself. Made adjustments to the IFR table, short pulse adder, minimum injector pulse width, and injector offset control.

It runs great, everything from idle to full boost is dead on with the way it was before. But starting it is a pain in the ***. It has to crank over for a few seconds before sputtering to life. And then idle is as tame as ever. Tried making some tweaks to the cranking FA mult stage 1 vs time table, but it had no effect. Ideas?

Edit: Added the log of startup. Still can't upload tunes to pt.net for some reason, but you can find it on the HPT forum at http://www.hptuners.com/forum/showth...king+injectors

 

I just went through a similar scenario. Some things that I found helped:

1. Reduce the VE 400, 800, 1200 columns incrementally until max improvement.
2. Use Russ RAF cfg for Idle in Gear and in park
3. Check other upgrade settings (i.e. TB Scalar)
4. Got more agressive with DFCO settings
5. Reduce overspeed and underspeed spark


You will need to patient for the VE and RAF changes as they are slow to learn, so change a little at a time, wait and see (don't change multiple things at one time or you won't know which are effective and which are not). As long as you are improving little by little thats the key. My 2 cents without having seen tune or logs.

As for the injector data, I had GM stock data for my Bosch 60's from vendor and I didn't deviate from what he gave me.

cheers

Edit: and adding thoughts
I also made the Cranking VE table columns 800, 1200 same as VE table, then made all cells up to 400 column = 100 then interpolated horizontal between 400, 800, 1200, copy and pasted 1200 column to the 1280 column, added "1" to 1280 column and interpolated horizontal between the 1200 column and 1280 column. I have a mild GT2-3 cam, this worked for me but you might end up trying to go further to the right with 100 in cells and blending in (whatever yields the best results, be patient for them to show up).
Two other tables to look at from reading (I didn't need) Startup Airflow initial (add 1 to 3 g) and Startup Airflow delay (make 80). Look for posts by EC in HPT on those two.
Under Open Rich/Lean vs. Airflow Bank 1 & 2 tables I went to 526 in 12, 14, and 16to help with transitions. Good EC writeup in HPT. He also suggests adding 526 to 0, 2, 4 for cam idle transitions (I didn't need this one). I also am trying the gas saving 350 for grins in 6,8,10. But I also had to update my mode vs. airflow table because my 5.7 with cam, blower, LT, etc. runs in different ranges than my stock 5.3 did.

 

The first issue with this is the Gen4 V8s have a virtual VE table, so it isn't as simple as just copying values and interpolating the data. I've also been talking with Justin at Blackbear over email. I haven't touched the Cranking VE table because it didn't make sense to me to make airflow changes when all I did was swap injectors. Justin confirmed that, so I won't be messing around with that table.

 

It seems that it goes rich right after startup, which tells me that its getting too much fuel during cranking and essentially flooding it out. What table in HPT pulls fuel during cranking?

 

I haven't looked at your tune file over on hpt forum yet but two good questions for you come to mind. First is where did you get the injector data from? Greg I assume? (Mr. Banish) Second question is with your E38 PCM and the injectors you are using and the IFR limitations of the PCM did you do all of your scaling correctly?

 

-2° cranking advance?

 

I've got a GenIV injector scaling spreadsheet. Not sure if Greg is the author or not. For the IFR limitation, I halved the values that the spreadsheet gave me and entered those in the IFR table, then set the IAT modifier table to 2.0 across the board to compensate.

Just ran into that, still need to investigate... I didn't mess with cranking advance though, so I don't see why it makes a difference now

Edit: that cranking advance table is untouched in all tunes I see in the repository, stock, aftermarket injectors or otherwise. All the same. So I guess thats out...

 

Try touching it, if for no other reason than to shut me up. It might be because of my cam, but it sure helped me. I'm not by my laptop, it seems like it's up to 12° or so.

 

I would love to know if there is a fix to this as I have the same problem with the same injectors. I had it messed with numerous times by my tuner, and it cranks forever. I just got to the point where I figured it was the nature of the beast.

 

Yeah sorry...I missed the 2008 part. The biggest differences to mine were the VE, VE cranking, and RAF tuning. Long starts and surging almost completely went away with that.