I have been driving the car today, loggin my maf output and this is what I got.
The third graph, yellow line is maf, green is tps and red is map.
This is when logging one maf connected to one cylinder bank. Looks like too much reversion is taking place to be able to use the maf for fueling. Based on this it looks that Alpha-N is the best estimator of airflow into the engine...
[quote="Belgian1979" Based on this it looks that Alpha-N is the best estimator of airflow into the engine...
Thoughts ?[/quote]
Your MAF is worthless as it is.....does the ECU have filtering? You might be able to clean it up with that but it will add a lot of lag. Trying to clean it up mechanically is generally quite a task and looking at what you have unlikely to succeed.
Your MAP looks fine so SD should be fine and certainly alpha-n will be fine but kind of a pain in the but to tune because nothing's linear about TPS vs Flow so you generally need more points int eh table and you have to tune each and every one. I would stick with SD and see what you have and if you still want to try a-n you can use the SD tune to quickly rough in the TPS tune
In-Tech wrote:What MAF are you using? Farther away from the engine will help, 92 grams??? Are you sure your transfer function is correct?
For the rest of us techies, I recently finished a supercharged 430 cu in LS for a Cadillac CTSV, how much hp is 884 grams?
Look at the TPS figures - never goes over quarter throttle.
I'm also wondering if more plenum volume before the MAF would be beneficial here. Or a venturi in the ducting from the MAF to the plenum. Ford used to put two of them inline in their six cylinder engines, Chrysler put one in their 3.5 V6 engined cars. That was for noise, but noise is resonance.
I'm going to say that 884 grams per second of air would require about 80 grams of fuel per second with a safe happy tuneup. That's about 288 kilograms per hour or 630 pounds per hour, which by my estimation means a CTS-V that can do a burnout from a roll at 90mph on street tires
In-Tech wrote:What MAF are you using? Farther away from the engine will help, 92 grams??? Are you sure your transfer function is correct?
For the rest of us techies, I recently finished a supercharged 430 cu in LS for a Cadillac CTSV, how much hp is 884 grams?
Look at the TPS figures - never goes over quarter throttle.
I'm also wondering if more plenum volume before the MAF would be beneficial here. Or a venturi in the ducting from the MAF to the plenum. Ford used to put two of them inline in their six cylinder engines, Chrysler put one in their 3.5 V6 engined cars. That was for noise, but noise is resonance.
I'm going to say that 884 grams per second of air would require about 80 grams of fuel per second with a safe happy tuneup. That's about 288 kilograms per hour or 630 pounds per hour, which by my estimation means a CTS-V that can do a burnout from a roll at 90mph on street tires
I didn't pay attn. to the TPS, was just looking at MAP vs rpm and Grams, hopefully OP will chime in with more detail. Agreed on more plenum and/or different ducting.
Pretty sure I ended up with 96lb injectors, I'll have to look back. Yep, still E67 Factory computer and yep, it's ridiculously stupid can't hook EVER fast. Those piston oilers were a pain in my arse with that 4.125 arm
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl
In-Tech wrote:What MAF are you using? Farther away from the engine will help, 92 grams??? Are you sure your transfer function is correct?
For the rest of us techies, I recently finished a supercharged 430 cu in LS for a Cadillac CTSV, how much hp is 884 grams?
Look at the TPS figures - never goes over quarter throttle.
I'm pretty sure its driveability that he's hunting for so it makes sense that it's mainly low rpm, low throttle he's looking at. WOT tuning is like 4 hours to get near perfect......then like 4 days to maybe 4 years on the get it driving nice part
You need either 2 separate intercoolers or an intercooler that's got 2 inlet tanks and one outlet........that's what they're for otherwise they wouldn't be made?
It's the outlet of one turbo feeding back into the outlet of the other , then you get oscillations as the turbos fight each other.
The intake consists out of 2 airboxes feeding a bank each. They each have a 90 mm tube connecting it to a cone filter of 4". There are 2 mafs in each tube. This is the reading of one of them. The mafs are 500 mm from the airboxes.
The maf curve is by no means tuned. I just used what was present in the ecu and only doubled the g/s because it's only measuring 1 bank
OK so it's a different problem, still pretty easy.......caused by the uneven firing order.
ITBs and MAF don't go together. Not unless it's a 4 cylinder or it's a single MAF feeding an airbox.
With no turbos / ITB you should be using alpha N.
In-Tech wrote:What MAF are you using? Farther away from the engine will help, 92 grams??? Are you sure your transfer function is correct?
For the rest of us techies, I recently finished a supercharged 430 cu in LS for a Cadillac CTSV, how much hp is 884 grams?
Look at the TPS figures - never goes over quarter throttle.
I'm pretty sure its driveability that he's hunting for so it makes sense that it's mainly low rpm, low throttle he's looking at. WOT tuning is like 4 hours to get near perfect......then like 4 days to maybe 4 years on the get it driving nice part
Can do that in an afternoon and take a break for tea with a QJet. (or even a Holley)
In-Tech wrote:What MAF are you using? Farther away from the engine will help, 92 grams??? Are you sure your transfer function is correct?
For the rest of us techies, I recently finished a supercharged 430 cu in LS for a Cadillac CTSV, how much hp is 884 grams?
Supercharged vs NA, quite a difference.
I'm indeed mostly below 20% tps and the maf isn't setup, just used the out of the box curves so to speak.
At those tps levels I'm usually seeing 45-50% VE with SD. That roughly equates to around 173,5 ci of air inhaled per every 2 revolutions or half that per revolution = 216 ci/min at around 2500 rpm.
Engine goes to 7500 and at 7000 I'm seeing close to 100 % VE.
Just throwing this out here : could this be the pulses caused by speeding up/slowing down of the air in the inlet tract due to the maf only seeing one bank ?
Belgian1979 wrote:Just throwing this out here : could this be the pulses caused by speeding up/slowing down of the air in the inlet tract due to the maf only seeing one bank ?
Probably not. On a twisted crank 8 you don't have an even spacing in the bank firing order so if this was anything to do with cylinder count in the bank you'd see an uneven pattern I'd think, but you don't. Also even a 3 cyl with a big can starts to look nearly steady state in air flow and a 4 pretty steady with most any cam so again this points to oscillations in the intake track so again whether the 4 are spaced evenly or not the flow will endup relatively steady.
An MAF setup can be very difficult to design and I think that's what you're seeing, it will also almost certainly cost you some hp. On a performance engine alpha-n is a sure bet and SD is easier if you've got a decent MAP signal which you do appear to have but you might be short on resolution......I'd try to re-tune with SD and your new ECU then if you're still not happy fall back to a-n.
