jungy

I'm still trying to perfect my idle and startup and have gotten it almost squared away except for a warm startup flare where the rpm flares high and then falls really low and hunts back and forth until it stabilizes where it wants to be. I have smoothed out the over/under speed timing to help with the cam idle. My BRAF and fueling are really good and the initial airflow adder isn't causing it.

I tried to play with the frictional airflow and the startup timing flare tables until I completely zeroed them out. This did absolutely nothing to fix my issue. It would be great to get someone experienced to look at my vid, log, and tune file that has some experience. I don't understand why it does this on warm start but on cold start it slowly falls to the desired idle rpm with no swinging high and low.

Applicable information about the car:
99 corvette
stock ls1 bottom end
FAST 102
Ls2 throttle body
232/234 .600"/.600" cam
799 heads mildly ported and milled to 59cc
Cometic .040 MLS gaskets

Here's the link to the video
www.youtube.com/watch?v=bWby9sKoDvM

CTD

Your BRAF looks to be quite high, how did you arrive @ those numbers?

Start up airflow has a delay table, it is cam revolutions before decay begins. Maybe try moving that to 50 to help stabilize start up. I'm just suggesting that to help until you get the balance of idle sorted out.

I've a couple of good links to help you with the idle if you are interested.

jungy

My BRAF numbers came from running the RussK idle airflow config. My LTIT and STIT are really good with the BRAF where its at.

When I had my idle spark advance at 26* the BRAF was around 9 in the fully warmed cells. The high numbers are just because I took out so much idle timing to get a more stable transition when returning to idle.

I have played with adding more airflow to initial airflow table and have set it up to 100 camshaft rotations and it still fired up and then hunted for the desired idle rpm just like in the video.

jungy

This is the guide that I have followed for idle tuning thus far.

http://www.hptuners.com/forum/showth...de-(w-pictures)

CTD

That is good guide but it is a drive by cable not the Vette drive by wire. We do not have the IAC air control valve, the blade is in control. I use a formula that cheats the scaler, it goes against the purists

I'm looking @ your MAF & dynamic air flow, both of those are showing right around 11 g/sec of airflow. That tells me your STIT will be off approx 3 g/sec looking at your BRAF numbers of 14 g/sec

Maybe this will help you:

http://www.hptuners.com/forum/showth...ghlight=clutch

jungy

Yeah that has been one of my concerns too knowing that its been written around DBC idle tuning. I've searched high and low for gen 3 DBW applicable info but haven't had much luck. Thanks for the link!

Briefly reading through that and comparing my tune file to a stock 04' z06 file and some other ls2 throttle body c5's from the tune repository I am seeing something that is jumping out at me. My off idle scalar from my factory tune was 0 as well as the startup airflow decay and everything else I'm seeing has the scalar set to 1 and the decay set to .800.

Do you think the car is jumping to an off idle transition early on during the initial startup and this is why my previous attempts at adding more air via startup airflow initial with up to a 100 cam revolution delay did nothing for me?

jungy

Well I adjusted my startup off idle scalar and set it to 1, set the idle airflow decay to 0, set the airflow adder table to 2 g/s across the table, and airflow delay to 100 cam revolutions. I even zeroed out the startup flare table so that it wouldn't interfere. This did not do anything for my warm start issues still the exact same problem as in the first log I posted.

As you mentioned CTD, my BRAF numbers seem suspiciously high. To me this seems like a calculated airflow problem and looking into solutions for the discrepancy between desired idle airflow and the dynamic airflow I found that to align these my ETC scalar needed adjustment. The ETC value that brought these back together actually was the stock value of .0255. Getting these back in line also brought my BRAF back into a more reasonable territory.

Could this mean my injector data is wrong? I have 36lb/hr bosch part number #0280155811 and everything I found when setting this said to use the part number #0280155868 injector data so that is what I did.

Here is a log from tonight with my tune and a modified .cfg file:

CTD

I don't see a WB in either log, are you just using FT's?

No idea regarding your injector data, if it is not right you chase. Can you lean your idle AFR? You can log IPW to verify.

Your IT's look right in the log, desired & dynamic don't agree. Desired, dynamic & BRAF should be close, certainly within 1-2g/sec as a target.

As a guess your cold start flares quite high, extra fuel is liked. Maybe your hot re start is over fueling, extra fuel is not tolerated like a cold start.

When I mentioned the scaler previously, I was not referring to the off idle scaler. You swap the TB so the blade area is now different, that's the scaler you may need to re calibrate.

One thing I do see in your OLFA table in your hot restart log the engine coolant temp is +103C. With higher MAP values & hotter coolant temps the OLFA table may start adding fuel during the hot restart.

jungy

I am running a LC1 wideband. If you are viewing the logs in vcm suite 3 the custom PID's dont transfer over correctly.

Here is a screenshot showing my wideband read out during the hot start issues. It is running ~9.4:1 all through the rpm swings and then finally falls to the desired AFR. Looking at it the fuel trims did not make the correction to lean it out it looks like it had to clear out the extra fuel on its own and then STFT's kicked in 6 seconds after it stabilized itself.

CTD

Your motor will choke on the 9.41AFR as it is. You don't have commanded in the screen shot , what is it indicating?

When you do a cold start, what is the AFR? Is it pig rich as well? It should be resembling you OLFA, not perfectly.

jungy

Took some logs this morning before work. I ran the idle airflow config just to get the cooler temps lined up and then once it was warm I shut it down and then tried warm starting the car with the stock cranking fuel numbers for a 04' Z06. It doesn't appear to be rich but actually a bit lean according to my b1s1 nbo2 sensor.

I forgot about how my wideband has to do its warm up cycle after starting the car and that's why it reads pig rich at first and then comes out of it. I also noticed that I have a b2s1 nbo2 issue where its locked at 447mv. This wasn't there previously so I don't think it is contributing to my issues but I will address this tonight.

Well I converted everything over to VCM Suite v3 so that you can view my logs better and view the wideband data. My wideband is placed on the same side as my non functioning o2 sensor.

CTD

I'm right in the middle of moving over to 3.0 while retaining my 2.24, has caused me some morning sickness, nightmares, screaming etc.

I've a switch rigged so I can lock the WB on, turn it off or have it cycle with the key. Start up you need the WB on & not cycle.

Logging the 02's is good back up & support for the WB, needs to be agreement, that includes injector PW. Commanded is such & such are the injector's following that.

jungy

For sure, I stayed away from 3.0 because everything for tutorials has been written around 2.24. now that I took the time this morning to figure out and get everything setup with my wideband and afr error in 3.0 I am finding it fairly easy to use. I like the xml layout better than the old cfg files I am finding.

I've been meaning to get my wideband powered without interruption in the run and cranking key position. Maybe i'll get out the multimeter and figure out where I can tap it at the ignition tonight. I'd prefer not to run a switch just so that I know its always on when the key is on.

jungy

Swapped out the bad o2 sensor on the passenger side and wired up my wideband to be powered while in the run and cranking key positions.

Here are my logs with the requested parameters:

CTD

Please post up your channel configs for 3.0, that should have the WB.

jungy

Dang, I was thiking these were self contained in the layouts.xml files and this was part of my excitement about 3.0. Anyways, here they are:

CTD

There is a channel configs located in the scanner, that is the one I need.

jungy

Here is the channels.xml file as well as a screen shot of my user defined maths for the wideband.

So I've always seen when I start the car the STIT is 0 and then after 2-3 seconds it sky rocketed. I gave messing with the startup airflow initial another shot and worked my way up to 6 g/s until I gave up that because it made no change to the issues. I figured what the hell I'll start going at the frictional airflow table. Well I definitely saw a hanging idle issue after adding 4 g/s across the board so I slowly worked it down to an added 2.25 g/s over the original values. It warm starts great every time now.

CTD

Good news I've not had a chance to re visit the files you have posted but I will. As mentioned I'm in the middle of saving renaming my 2.24 files while trying to adapt to 3.0. I really messed it up by trying to bring a new laptop into the mix, not liking it & getting another

I'm guessing your airflow number are starting to show some agreement. Those are basic's just like injector data, when those are right the rest starts to fall in to place.

As you are doing picking & chipping away, perfecting the tune!