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TUNE FILE ATTACHED IN POST BELOW w/ Newly Added FIC injector data, of which I'm not sure is right...
Truck fires right up at full temp and ice cold, but will take 3+ seconds worth of cranking to fire up when its warm. Guaranteed to do it if it sits for 30-60 minutes after being at full temp.
07 Suburban
5.3l, 76mm @6psi
LS7 MAF
Idle, cruise and wot are within +/- 2%.
Could it be the first few cells of the MAF low?
High and low mafs are attached
Have you used the scanner to see if the cam sensor is working.
hmm...I have not to looked at the cam sensor. Can you further explain your reasoning behind this?
**keep in mind this is a stock cam.
I looked into the file and notice there is a cam angle warmup factor. This is 1 or 0 and tells you if the warm or cold tables are being used. May try to look at this to determine what table it is referencing...
I'm still leaning towards an incorrectly scaled MAF for the lower values. Looking at a stock ls3 at 1000 hz, it is in the .3 range, were mine is currently at .256.
Correct me if I'm wrong, but my understanding of what is happening is: The long crank is slowly opening up the throttle (allowing more air) which to me means there is too much fuel being introduced when the car is warm? Based on this, I would likely decrease the lower values in the MAF curve?
Anyone have a MAF curve for an LS7/LS3 card style MAF in a 5.3L with a stock cam? I'm fairly confident in my curve from 2200 HZ and up, but dont have much confidence in values below 2200 HZ.
just matched my 8th maf revision with a 3rd order poly. The truck runs fantastic and the trims are within 1%.
**Big thanks to DSTECK for the excel file that made that a piece of cake!
I will report back in 1 hour with warm start results.
Still cranks for 3-4 seconds before it fires up after being parked for roughly an hour.
Do I start scaling the startup airflow graph to compensate for the MAF change?
What do the IAT temps look like when this happens? Getting heat soak maybe?
Just had a lazy start and the log had:
127F IAT - 55 Ambient
155F ECT
~1 hour 2 min after engine was shut down.
I could be wrong but I don't think the issue is in the MAF Table. Someone else can chime in but I think during cranking the Flow across the MAF wouldn't be steady enough to calculate proper fuel. That's why they have a "cranking fuel" table, after start enrichment, etc. I thought your IAT would have been higher leading it to pull timing after heat soak but 127F on a stock table is something like -5 or -6 I think. Do you have a log of it right after the 4 second cranking? That might have some clues as to what's happening just prior.
I see when I start cranking the MAF reads ~2000HZ and climbs rather consistently. I think I have eliminated the concern of it being the lower MAF cells however after I had matched it with a 3rd order polynomial.
I do have a log, I'll post it tonight.
This has me going crazy!
*plan to experiment with startup timing as I've read sultan suggests. I've messed with the FA mult stage 1 tables also with little success.
The only fuel table I have for startup fuel is the FA Mult Stage 1.
I do not have Prime Pulse Mass: First Pulse Mass: First Pulse Delay: Second Pulse Mass: or anything else for that matter. The only table I see is the FA Mult Stage 1??
I am in the advanced view.
I got some injector data from FIC today.
Entered that.
Only changes to tune from stock at this point:
MAF (dialed in with stock injector data except doubled stoich and halfed IFR)
FIC 60# Injector Data
Threw off stft's by -25%.
Adjusted MAF low table and logged STFT's. They seemed sporatic and adjustments seemed to yield inconsistent results.
Not sure if I have the correct data, as I've read they have passed around the wrong data in the past.
got the tune attached. I would greatly appreciate it if someone were to check the injector data