.........continued from the end of this thread:

https://www.performancetrucks.net/fo...=412549&page=3

If anyone is new to this whole discussion, let me briefly recap. I needed more fuel because i was maxing out the 42lb'ers with an IDC of 105+% during the shift points. I built myself (and a couple others) a set of multec -to- LS1 injector harness adapters and stuck some Siemen DEKA 60's in the truck to help out with the fueling issue. Needed some help with the new injector tables (which DEWY and DR. X helped out with) and buckled in to try and make it all happen. All this with the stock 8.1L fuel pump which is supposed to be a different animal than the small block pumps. The install and a bunch of other crap about that can be found in the referenced thread above.

Now for the good stuff.......
.............Can you say, "90% TPS @ 146kPa = 56% IDC?"


F'in A I can!!!!

So that right there was enough to make my day. I spent a good deal of time working out the VE table and trying to get things back to normal after the injector install. So far the stock pump is having no problems with supplying fuel to the 496 @ 6psi with the 60's in there . The idle is very nice when I am sitting with it in gear warm and cold....its perfect. When i put it in Park, i can feel a very very mild stumble about every 15 seconds and you only really notice it if you are actually sitting there trying to feel something. Other than that it feels great. Acceleration is good and all around the truck feels fantastic. I did not do any WOT runs from a dig yet because i dont have the boost VE table quite nailed down so I didnt wanna push it. I want to steer this into a fueling and injector table discussion, but let me first address one concern. Not even really sure if its a concern or not because everything is working out great, but here goes.

For a year or so I have had the Kenne Bell F.P. and Vac/Boost gauges in the truck. The fuel pressure gauge would sometimes give me a problem with sticking or bouncing around....but would eventually fall into place at around 60psi +/-. Today i installed my new B&M blackout gauges (they look awesome, pics in the reference post above). I start the truck and found that the truck idles at at 49psi . With a little gas (under a load) it will gently rise through the 50's until it hits about 61-62psi at almost WOT. Not sure if thats normal, or even whats supposed to be normal for this pump, but it had no problems keeping up and even went rich a few times to about a 10.80 AFR under boost....so I know its doing its job. Anyone wanna take a stab at why this is? Is it normal? I have some other questions too, but i will take it slow because I am very happy right now with the whole swap and dont want to push my luck. Here is my current tune and a log of that tune to have a look at if anyone is interested.

 

FP should vary like that for a return style(boost/vac referenced) setup.

FP should = base FP at 0 boost/vac. Base FP is where its at with the vac line removed from the regulator. It will drop below that when in vacuum and rise above that when in boost. That's why you only need a single value in the IFR table for all MAP values. The FPR adjusts the FP to compensate for the effect of MAP on IFR.

 

yeah, 49 seems low but not unheard of. As long as it increases with your foot, don't sweat it. 58 psi is atmospheric. It should be 1:1 boost referenced. So at 1# of boost your should see 59spi. 2#'s 60psi, so on and so on give or take .5 psi or so. You are a different breed with the 8.1L. Your rich "bumps" before that were tiny are now a little more announced with the larger injector openings. Just get to boost tuning. I figured those larger cylinders would make idling an easy deal with you.

 

Cool, well that makes me feel better about the pump pressure. What i need to try and correct is the lean tip-in i have when i hit the pedal. It will take about 5 frames to line back up with the correct AFR. Thats a little to long for my taste.....2 frames would be nice. What do you mean by the "rich bumps" and them being a little more pronounced?

Where do i need to start tinkering to get those lean tip-ins taken care of?

Also, Dr. X, if you have not already.....can you take a look at that tune i posted? I compared it to the tune you sent me (just the injector area) and noticed quite a few differences from my tune. Octane scaler and a few others im to tired to think of right now. Can you tell me if i need to change something in my tune from where it is now?

 

I'm back to MAF until we have Acceleration enrichment tables because of this lean tip in. "Lean" is a bit of an understatement too. I can stab the throttle and cause the engine to stumble unless it has reached full operating temp.

 

I am aslo considering this.....lean scares me. Did you look at that log Justin? Did you see how long it takes to get to commanded AFR? Is there something in the works to correct this? Is there a way to get the a MAF tune as precise as a SD tune with the fueling?

Could you give me hand with it?

 

Could you refresh me (based on my tune) what i need to change to revert back to MAF?

 

It's tad more complicated that just turning it on since you have a cusotm OS. Justin will have to walk you thru it. I tried it, I have something screwy with my MAF air flow calcs. I gave up quick. LOL

I just meant "rich bumps...announced" cuz with large enough injectors now you'll see the spots magnified where you were previously over compensating.

 

I know i would have to change my MAP sensor back to the 1bar, but other than that it should only be a few other tables that need to be reverted back. I never removed the MAF, only unplugged it. I have most of my older tunes and figured other than those minor changes, it wouldnt be too bad....but i wasnt sure......so i figured i would ask. I figured i would have to flash back to my original OS though.

 

There is something to this "large enough injectors" causing problems to be more pronounced.

As far as swapping back to MAF, you can do it without swapping the 1 bar in, you just have to commit to running MAF full time. I switch to MAF full time at 1600rpm for the time being using B0120.