Cold Start Issue

[zack_johnson]

I am having a cold start issue. Main VE is dialed in, just will not start without using the throttle, use it for maybe 15 seconds maybe then it will idle and it is fine starting when warm. It’s just the first start of the day. I have messed around with the idle air flow and the after start initial adder, the commanded and actual AFR are very close now but I am not sure if I am not getting enough air as its saying idle desired is around 23g/s but idle base is 16g/s. Could I get some inputs on this? Thanks

[tana99ss]

I will say im not a fan of your BRAF setup you go from 16 g/s to like 7 g/s. Start up is adding 7 g/s I would try to go 23 g.s and work you way lower. Also, i see you have EGR and catalyst Timing stuff still active.

add these to your log and upload data.... get a longer timeframe too.

Idle Adapt (STIT)
LTIT Gear/ACoff
LTIT PN/ACoff

[zack_johnson]

I kind of adjusted the braf when I was tuning. It is happy where it is in operating range. Doesn’t stall or no hesitation. So you’re saying start at 23 at the coldest ect and then slope it down from there? And I will add those pids tomorrow and make a log

[edcmat-l1]

Really need all the build specs to analyze the files.

[zack_johnson]

2000 GMC Sierra EXT cab Z71 2 1/2" lift with 33s
Stock rebuilt L33 5.3 with 799 heads
Built 4L80e with 3000 stall
BTR stage 4 truck cam V2
"TBSS" intake with a Holley 90mm drive by cable throttle body
Holley fuel rails with 33LB AC Delco injectors
K&N cold air intake
Speed Engineering long tubes and x pipe to midpipes with 2 black widow race venom
AEM AFR wideban 30-0334 logged through analog via the pro link

[edcmat-l1]

First thing is, the VE is not dialed in. The shape is nowhere near correct.

Second thing is, you need to post a data log of it from cold start all the way to operating temp. My guess is your cold start issue is the IAC and TPS haven't been setup correctly. Only way to know is to see the counts at operating temp.

Lastly, all aftermarket cable drive T-bodies need the IAC passages modified or "ported". Do a quick search and you'll understand.

Read up on speed density tuning and get that VE fixed.

There's plenty more that needs attention but that should keep you busy for a while.

[zack_johnson]

So even when I am getting all zeros or less than 1 either way in the scanner using the afr error it’s not dialled in?

[edcmat-l1]

So even when I am getting all zeros or less than 1 either way in the scanner using the afr error it’s not dialled in?

I'm telling you there's no way that's an accurate depiction of the volumetric efficiency of that engine. The shape is wrong. The drastic steps from one column to another is unrealistic. The peaking at 8000 rpm is unrealistic. It's not real, it's not correct. I don't care what your wideband error says.

You have it in closed loop so of course the wideband is going to stay at or near zero correction. Your trims are keeping it at stoich. You don't understand the process of dialing it in.

Turn off your long-term trims. Plot your short-term trims in a VE histogram. Apply those to your VE table Copy/paste/multiply by.

[zack_johnson]

It was all within 2 before I turned the trims back on. And only revving to 6000 so does everything above that still matter?

[edcmat-l1]

It was all within 2 before I turned the trims back on. And only revving to 6000 so does everything above that still matter?

OMG dude the VE is totally not right I don't care how you came up with it. I'm telling you to redo it using your short-term trims. Turn your wideband off. OL tuning is dumb. It is the most overrated, overused, BS ever introduced to the common man.

[edcmat-l1]

Your VE. Bogus numbers and shape. Totally wrong overall.

[edcmat-l1]

What it should look like in general. Numbers might vary somewhat but this is the overall look you're going for.

[zack_johnson]

cold start but the scanner stopped and a log file with LTFT off