Newbie tuner needing help with idle!

[rossp]

I have a 99 silverado with an lq4/4l80. I have just installed a cam (224/227 580/585 108 9.5* overlap) and i am trying to get this thing to idle right. This is my first time tuning anything fuel injected. I have my ve down pretty good for cruising and wot, and i believe its good at idle. Im still fighting getting my idle in check and it seems like ive tried everything! Could someone take a look at my tune to see if there is anything obvious out of wack?

[darcy]

I think you VE still needs quite a bit of work.
It's a bit all over the place and should not have such sharp spikes and dips. You should also correct the Out of Range cells.
Your IAT VE Multiplier is also a bit odd
Just checking that your fuel system is actually 31# injectors, and manifold referenced?

I've pulled your VE into a shape that I would be more expecting of, but your injectors need to be right.
Should also set your DCTs to trigger on First trip so it falls into SD mode quicker. :)

17055

[rossp]

[QUOTE=darcy;207606]I think you VE still needs quite a bit of work.
It's a bit all over the place and should not have such sharp spikes and dips. You should also correct the Out of Range cells.

I agree that it was all over the place. I was only changing the cells that i was able to hit in my logging. Your numbers are significantly different but I will give it a go.

Your IAT VE Multiplier is also a bit odd

Is this B4901 Charge Temp Blending or is there a table im not seeing? I dont believe i have messed with it, but its possible my previous tuner did.
Just checking that your fuel system is actually 31# injectors, and manifold referenced?

It is a factory return system. I believe i have the ifr correct. The injectors are 5.3 flex fuel which are rated 33#@50psi. I converted them to my 58psi base pressure and came up with 35.59#.

I've pulled your VE into a shape that I would be more expecting of, but your injectors need to be right.
Should also set your DCTs to trigger on First trip so it falls into SD mode quicker. :)

[rossp]

I flashed the changes you made and it did not like it at all. With any throttle it would go lean.

[rossp]

I agree on the VE. I only changed the cells i was able to hit.
Not sure what the IAT VE multiplier table is. I havent changed it but my previous tuner very well may have.
My injectors are stock 5.3 flex fuel. They are 33#s at 50 psi base pressure. I converted the flow rate to my 58psi pressure with an online flow rate calculator and the number it gave me is what i entered for the IFR.

[statesman]

Have you changed the fuel pump?

[rossp]

Yes I am running an aeromotive 340LPH pump.

[statesman]

I just did a quick google to look at your fuel pump and it appears to have a rated pressure of 40psi, not 58psi.

[rossp]

I was mistaken on the pump im running. Im actually running the AEM 50-1000 pump. It is 320lph@43 psi with a max psi of 90.

[darcy]

The automotive instructions still give it a flow of 275l/hr @ 60psi, so it should be more than capable in this application @ 4bar. Agree with the line of thought that fuel pressure needs to be right.

I'm not familiar with those injectors, but I don't know of any stock injectors rated at 50psi - I just had a poke around in a stock L59 tune and 35.404lb/hr looks to be the flow @ factory bar. If you have your fuel pressure set at 58psi (set with the vacuum line off of the reg) then that is the number to use across the board in your {B4001}

Ignore my comment about IAT Multiplier - it looks fine. I meant to delete that line before posting.

[rossp]

I havent confirmed my fuel presure but isnt the genIII non flex fuel stuff based off of 58psi? I read that my injectors are rated at 50psi base pressure. I could be completely wrong on this though. The injector part number is Denso 25326903. I have attached the tune file from the exact tahoe these injectors came out of.

[darcy]

Sorry, was looking at the wrong years of vehicle. In that case 35.59lb/hr looks prettyclose to me :)

[rossp]

Thanks for the help. At least I've got one thing right in the tune. I'm still fighting an idle issue where it will idle fine for 39 secs or so and then stumble and die.

[darcy]

Post a log of it idling and stalling so we can see what is going on.

Desired airflow number are MASSIVE, by about +10g/s, should not need that to idle.

[rossp]

Here is a log of it dying at idle a couple times and a short drive. Its also surging really bad at low vehicle speed when coming off idle.

[statesman]

The automotive instructions still give it a flow of 275l/hr @ 60psi, so it should be more than capable in this application @ 4bar. Agree with the line of thought that fuel pressure needs to be right.

I just had a quick look earlier and didn't find the automotive instructions. I'm always wary when I see something rated at a lower value than the intended use.

[rossp]

My problems ended up being in the ve table. I spent about an hr manually smoothing it over and it's great now. Who knew the ve table was so important haha. Also I found the fuel correction spark table. Are the values in this table added on top of my high octane spark table?

[joecar]

Yes, in SD the VE has to be good, in OLSD it has to be exact.

Yes, B5908 is added to current spark timing.

[joecar]

I take it your FPR is manifold referenced...

[joecar]

Generally, you can "cheat" by doing eyeball-interpolation of the VE table (i.e. you make the un-hit cells flow with the hit cells... this is like smoothing but really is not smoothing).