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Maybe I'm having a brain fade but I don't see any direct relation to adjust fueling during closed loop vs intake air temp.
Is the only adjustment for this done in the cyl. charge temp. bias? ECM 13001
Do I also assume there is something going on in the back round HPT doesn't give us access to?
Attachment 155928
Changes in air temp don't correlate with needing changes to fueling, only spark. ECT does though, both fuel and spark. That's why there are tables to adjust for ECT but not IAT.
What problem are you having? Hot starts?
I have not seen any compensation for IAT other than the blend and filter. The IAT is directly inserted into the equation that derives VE.
This is the math I use to derive a VE value from the MAF, MAP and IAT. I start MAF only and actually log a histogram to create a startup VE table.
Dynamic air calibration from MAF
Dynamic Air Calculated =
(MAF gms/sec X 120) / (#Cylinders X RPM)
VE Calculation from MAF
VE=(DynamicAir X IAT in Kelvin X 0.28705) / (Cylinder Volume X MAP in Bar)
Now put both parts together.
VE=((MAF gms/sec X 120) / (#Cylinders X RPM)X IAT in Kelvin X 0.28705) / (Cylinder Volume X MAP in Bar))
VE Equation
[16.71] is HPTs way of inserting MAF in gms/sec
[12.56] is RPM
[15.240] is IAT in Kelvin
[11.99] is MAP in Bar
120 & 0.28705 are fixed values
8 is Number of Cylinders
0.7875 is volume of 1 cylinder in Liters
Not necessarily a huge problem I'm aware of.Quote:
Originally Posted by SiriusC1024
My hot starts are acceptable enough for me now. They would not be good enough for someone who is not willing to tolerate 15 to 30 seconds of very lean behavior after a short to moderate heat soak.
What I am noticing that got me thinking about it, during the same ECT of say 180f
yet IAT near 50f, I am seeing 15 percent plus STFT compared to when the IAT are 90f.
I assume since cooler air is more dense, the engine would need more fuel to reach the same lambda target, assuming all other variables are close to the same. I also assumed the PCM is accounting for this in some manner.
It has been suggested to me to run my combo. in OL but this is one of the reasons I don't want to go strictly OL. I just restrict CL LTFT to min. positive change and little neg. change but CL STFT has much more room to operate.
Add 0.10 to your charge temp bias table for a start, add 10% each time after until the trims fall inline. No need to go over 1.0.
Actually, i see your table was set to 0. Try this change.
I also assume at this point, the cooler the air, the more oxygen will be present in the same intake trac. volume, at the same observed pressure, therefore requiring more fuel to reach the same lambda target, at the same observed load.
https://iopscience.iop.org/article/1...3/1/012039/pdf
As you probably noticed, the engine is boosted. It was suggested to me some time ago to bias the charge temp. more towards IAT. As you can see I ended up at zero across the board as a test and haven't moved it back. I did that before ambient temps. dropped significantly and never finished adjusting the VE table in the boosted areas and just assumed I would finish it next year. The IATs is in the charge pipe, about 6 inches before the throttle body.Quote:
Originally Posted by 04silverado6.0
By moving the bias more towards the ECT, I would expect the fuel trims move farther from the target. Why would you expect them to move in a negative direction closer to zero?
I guess my most immediate question now is, what exactly does the charge temp. bias table do, in the foreground and background and/or how does it work?
I made a mistake in my first post. If your iat is in the manifold you will set it to 0. I have had some issues with fuel trim variation on hot starts particularly in swaps with poor routing of intake piping. Raising the bias table will help offset that error on a hot start.
The table works basically how you would expect. With the bias towards iat you will have heak soak under the hood greatly interfere with fueling.
Mine behaves completely opposite of how you are describing. More bias toward the IAT compensation corrected the fueling dance with varying IAT readings. I have the factory GM airbox on my Express van. It will hit IATs of 200F in summer and as much as 140F in the dead of winter in 20F ambients sitting in traffic. I played with those IAT settings and got it tamed a good bit. Then ended up adding fuel to the post startup table that is referenced against IAT and Time to eliminate the hot lean re-starts.Quote:
Originally Posted by 04silverado6.0
With the OEM Express Bias and Filter it would run rich right after startup, lean out as the CTS increased, then richen up again as the IATs climbed. The IAT was not contributing enough at or near idle.
Just so we don't get too far off track, (although Fast4.7 reminded I could attack the heat soak restarts again from his angle) my observation is more at steady state scenario, such as 1600 rpm, 50 mph, light load, when fresh cool air is abundant.
The charge temp. bias table makes me think it is referencing something else. Such as when the IAT/ECT is "X" add or subtract from this table?
I believe the warm/hot restart lean issue is actually a fuel rail temperature/vapor issue from the stagnated fuel in the rail being somewhat of a mix of pressurized liquid and vapor rather than completely liquid fuel. After a short period of time the vapor is purged from the rail and replaced by cooler fuel. The IAT adder trick merely allows for added fuel delivery to compensate for that period of time. I first noticed that hot compensation used on a Vortec 4.3L from the factory. My first test was actually using the 4.3L values and it nearly eliminated the hot restart issue. At the time I was still running the OEM injection spider on a 350 and thus prone to the same heat soak as the 4.3L version.Quote:
Originally Posted by abc
The charge temperature calculation is odd for sure in the PCM.
273.15 + IAT + ((IAT-ECT)*Bias)
If the blend bias value is Zero the IAT is the charge temperature. If the blend value is 1.00 the ECT is the charge temperature. Both the IAT and CTS value changes are filtered by the filter term values. 0 is the slowest change and 1 is a fastest change. Generally speaking at higher airflow volumes the intake charge does not have as much time to be heated by the intake and cylinder head ports, thus the charge temperature shifts more and more toward the IAT as the airflow increases. The filter value also needs to change more rapidly with higher airflow mass.
If you are running the complex blend value created above it is substituted in place of the IAT value in the VE equation I posted earlier in this thread.
You're on the right track suspecting the complex temp model. Where is the IAT located?
In every vehicle ive made adjustments to this, going towards a ect bias richened the hot start. I have been able to raise the bias toward ect to the point of a slight rich overshoot which worked awesome.
"direct relation to adjust fueling vs intake air temp"
Not a per-engine thing, just hard science. Why dyno "corrected" numbers work.
I mean, you can cheat it with the sensor calibration. That would get what you asked for, but unless it's not calibrated right, leave it alone.
This varies due to intake pipe routing and sensor placement. Compare a stock truck file to any gen 3 car or van and see the difference. A hot metal cold air intake behind the radiator on a swap will need this adjusted.
Agreed and an 8.1L is even more different because of its aluminum long runner intake manifold.Quote:
Originally Posted by 04silverado6.0
How would you guys quantify the results of a change to the charge temp.bias table?
Would you expect to see small changes in AFR or large changes?
In your case the first adjustment i would copy a stock table in. I think that will be your largest change.
The largest change would be to go the complete opposite. I believe the deff. reads 0 to 2 adjustment range. I have run it with the stock table and was curious as what I may see as a change during a WOT pull when ECT changes less than 5 degrees but IAT changes more than 40 degrees.
I admit I haven't been scientific about the testing but, as of now what I am noticing with the table biased as far as it can be toward the IAT is it wants less fuel as the IAT rises during a pull. It was biased more toward the ECT (stock bias table) when I did the majority of VE tuning.
Quote:
Originally Posted by 04silverado6.0
Quote:
Originally Posted by Fast4.7
Quote:
Originally Posted by 04silverado6.0
He is most often wrong.Quote:
Originally Posted by abc
When exactly have i been wrong?Quote:
Originally Posted by edcmat-l1
Twice here. Every post in the TCC thread. Your P59 thread. Your "diag" claims. Saying I don't give any useful advice. So far as I've seen, 100% failure rate.Quote:
Originally Posted by 04silverado6.0
Best useful advice I could give here is, everyone should ignore anything you say.
He was also suggesting a triple disc lockup clutch for towing abuse.Quote:
Originally Posted by edcmat-l1
Even circle d recommends a triple disc for towing.
Numbers above 1 do not actually change anything. No need to go over 1.0.Quote:
Originally Posted by abc
Back to answering your question. The one I played around with trying to figure it out went like this. I tried both the 0411 L31 Van calibration as well as a LS P59 6.0L Van calibration just to get a feel for how the drastically different settings reacted. Neither was ideal so I went back to the L31 setup that was the closest to mine. Same air box and nearly identical ducting setups but obviously different intake manifold and cylinder head designs. I tested it from a 30F cold start at idle and let it warm up to an IAT of around 140F, took a decent amount of time, probably 30 minutes of datalogging. With the bias table out to lunch and not enough bias toward the IAT it was 6-8% rich right at the point it went into closed loop around 120F with an IAT sitting around 40F. As the coolant warmed up to the 195F thermostat opening it slowly leaned out to a point it was 6-8% lean. Then as the radiator and engine heat started heating the engine bay and intake tract it started richening back up until it was 8-10% rich again. At higher airflow rates the fueling was pretty much spot on with IAT changes, it was only idle and very low air/flow situations that had that table drastically throwing things off.Quote:
Originally Posted by abc
Well a more reputable converter builder recommends a wide single disc as being far more durable. I have even seen the triple discs smoked in 10K miles with minimal towing.Quote:
Originally Posted by 04silverado6.0
I see you have plenty of time to scrounge the internet and be a dick to everyone. Dont you have anything better to do? Your business still open? Pretty booked up with appointments over here.Quote:
Originally Posted by edcmat-l1
Who is your more reputable converter builder? Im sure yank will have the same recommendation.Quote:
Originally Posted by Fast4.7
Just to assholes like yourself who wanna talk shit about people.Quote:
Originally Posted by 04silverado6.0
I didn't personally attack you. You did me.
I've been on vacation for a week. If you haven't noticed I haven't posted in a week. Some people actually unplug now and then. Today I'm resting up so plenty of time to be a dick to you.
Business ain't bad.
Like I said in the other thread. You're a bullshitter. You don't even have any real automotive background. You brag about being a better diag guy than an ASE tech and then use a timing chain and guide story. That ain't diagnostics.
You've taken multiple personal shots at me. Why can't you keep it technical? I tell you why, because you can't.
Yep I'm gonna be a dick to you forever now.
I challenge you to post anything of advanced technical knowledge or skill.
^^^ Perfect example right here. Tell everyone how I never give any useful advice.Quote:
Originally Posted by 04silverado6.0
You figured out the ratio of negative feedback on roughly 5K vehicles? You know, with your math skilz.
This is called irony. Because you're the one who went scrounging the internet looking for negative feedback to post here to make me look bad. That's called projection. Accusing someone else of doing exactly what you're doing. It's common among liberals.Quote:
Originally Posted by 04silverado6.0
Another childish personal shot at me. Why can't you keep it technical? Because you can't.Quote:
Originally Posted by 04silverado6.0
Attachment 155984Quote:
Originally Posted by 04silverado6.0
You trying to log into my account now you POS??? Real strange I get this message RIGHT NOW and have never gotten that message since I been on this board.
You're a real POS buddy.
Hptuners forum, the unexpected source of entertainment for the holidays.
Did you try reverse IP lookup and see if it's the general area? Could always use a VPN though I suppose.
Quote:
Originally Posted by abc
There are a lot of things that can be adding up to this. But first start with this.. Does this have an actual drivability problem? Is it something you would notice if you weren't hyper focused on a laptop. This is not a condescending question.. but a serious one.
Beyond that.
Widebands/o2 sensors do not function the same hot vs. cold. The sensor data sheet will show you how temp will skew them. Long tube headers changes how fast the o2 sensors warm up. Make use of the factory CL time delay to ensure the o2 sensors are hot and ready before going into CL.
Only the fuel that is vaporized will burn. On these restarts.. while they maybe a decent ECT is not the same as a engine that has been running. This effects how much of the fuel that was injected actually burns.
On hot restarts you are also dealing with overheated fuel in the rail. Even if it doesn't get to the point of vaporlocking it will still effect fueling. Water doesn't have to boil off the sidewalk to turn to steam/evaporate. Same with gas in a 200F rail on shut down. Part of it will vaporize. It changes the fuel mass per volume. SO you can see how that is a new wild card.
On the ECT/IAT bias. If you didn't know.. it's meant to be an average between ECT and IAT. The math should be done in kelvin. For instance 100 F isn't twice as hot as 50F. Kelvin and Rankin fixes this. So at lower airflows you'll see it biased more towards ECT. This is because they assume the slower airflow though the engine is being heated by the intake ports, manifold, etc. The other table is the filter. How fast this calc can move. I honestly do not suggest messing with it.
I did and yeah, it doesn't mean it ain't him.Quote:
Originally Posted by aaronc7
You zeroed out the complex temp table. Really to answer your question depends on the location of the IAT sensor.Quote:
Originally Posted by abc