Boosted E38 Help

[jnjprfrmnc]

Hi all, this is my 1st boosted E38 and kicking my rear, it's a turbo 2010 Camaro L99, a fellow tuner told me to tune through the MAF and the MAF curve is ugly now the idle is not to smooth and light throtle is a bit jerky after that it seems to run ok WOT AFR looks ok but like I said the MAF curve is ugly and around 5500 RPM seems to loose control of the fuel can not get the AFR below 11.8 checking the fuel presure in the AM, FYI 10psi, GT500 injectors, MAF is in a blow through 4" pipe before T/B, and no resinator in the exhaust other wise stock. Thanks for any help, Justin

[jnjprfrmnc]

They are putting in a boosta pump in now for the fuel issue, but no one has an answer to the MAF tuning question.

[odd boy]

Get me the file, please.

What AFR did you get @ wot? Post the dyno sheet if you have it.

[ringram]

MAF+Boost=Shit
Max airflow = 512g/sec

Answer=Delete

[odd boy]

MAF+Boost=Shit
Max airflow = 512g/sec

Answer=Delete

I’ve different opinion; we did many cars before with and without the MAF. It would be much better if he can get us the requested answers in order to have better look.

Especially, he is saying the idle isn’t good. So, he has other issues more than the MAF tuning!!!

[eficalibrator]

MAF+Boost=Shit
Max airflow = 512g/sec

Answer=Delete
I sincerely disagree and have 600rw, daily driven reasons (http://www.calibratedsuccess.com/pics/TurboLS3_new_MAF.JPG) why.

Some thoughts for the OP:

1) Did you use all of the proper injector data for the GT500 injectors? (recalculated short pulse adjust, offsets?)
2) Did you force MAF-only mode via RPM threshold and perform calibration of the MAF transfer function down low in steady state and under a moderate load?
3) Does your new MAF have a clean airflow entry that results in a clean, consistent signal when performing steady state testing? Bigger is not always better if you're getting noise. I have seen where larger MAF housings (I tried a 103mm before settling back to my current 90mm housing) gave me a +/-300Hz fluctuation that was all but impossible to dial in consistently. My 3.5" tube setup only sees about 11kHz at 67#/min airflow, so it has plenty of room to grow.
4) You better get the MAF curve right, since trying to dial in a VVT car on the virtual VE tables will keep you busy for a good, long time.

[odd boy]

1) Did you use all of the proper injector data for the GT500 injectors? (recalculated short pulse adjust, offsets?)



is there a way to find these data for any injector, because I do trail and error untill I get best tune!!

But for GT-500, I have them because I do tune ford engines

6293

6294

[eficalibrator]

is there a way to find these data for any injector, because I do trail and error untill I get best tune!!

But for GT-500, I have them because I do tune ford engines
Unfortunately, it's not as simple as copying the exact Ford values into a GM controller since the two OEMs have a different definition of exactly what point on the curve is the "offset". I went through the trouble of converting all the FRPP data a while ago and published the revised GM-specific values (corrected for 4 bar operating pressure) as part of my "GM Beginner's Guide" DVD. The DVD covers both the "how" and the "why" of these changes in the context of tuning an actual car using both EFILive and brandX software. There's a link to the Summit sales site for it in my sig since I don't sell them directly.

[jnjprfrmnc]

Sorry it took so long to get back here but efi is right on track the MAF signal is crappy idle in P/N 1200-1600hzand in gear is 1800-2200hz having them make a 3.5" charge pipe and thebap gave me control of the AFR and yes all the correct injector calc are there.

[odd boy]

Sorry it took so long to get back here but efi is right on track the MAF signal is crappy idle in P/N 1200-1600hzand in gear is 1800-2200hz having them make a 3.5" charge pipe and thebap gave me control of the AFR and yes all the correct injector calc are there.

I didn't understand!!!:w00t:

[ringram]

How do you get around the ECU hard limit of 512g/sec without messing up IFR or similar then? Surely if you run mafless you can leave everything nice and straight and read airflow up to 3 bar much more accurately well pass the hard ECU airflow limit of the MAF tables!?

[eficalibrator]

The ECUs with the 512g/sec MAF limits also have a 63.5#/hr IFR limit, which is below the actual flow rate of a set of SD60's anyway. You'll have to perform some scaling to get around this either way, so why not just go with a single scaling factor that opens up the effective MAF range as well. ;) Of course, there's (more than) a few other things that must also be scaled at the same time to keep everything happy, but it's certainly doable without compromise. No need for a custom OS, really. The factory OS is surprisingly flexible as long as you play by the rules of physics.

[ringram]

Ok, Ill run with that as an option. So for someone needing to do this to make it work where would they find a list of tables to alter?

[gmh308]

How do you get around the ECU hard limit of 512g/sec without messing up IFR or similar then? Surely if you run mafless you can leave everything nice and straight and read airflow up to 3 bar much more accurately well pass the hard ECU airflow limit of the MAF tables!?

Also the 2010 Camaro, and '08 & 09 OS's as well have 3kg/s+ MAF capability. (Exception ZO6 Corvette...and probably a couple others...).

[gmh308]

MAF+Boost=Shit
Max airflow = 512g/sec

Answer=Delete

Such an "Imperial" approach to matters...:grin:

[gmh308]

Does your 600 RW DD reasons MAF read reasonably smooth with the split feeder pipes coming into one? Is that a 100mm pipe or 90mm that the MAF is mounted in? Looks like a 90 in the pic as smaller than TB, so just checking. Nice! :)

"http://www.calibratedsuccess.com/pics/TurboLS3_new_MAF.JPG"




I sincerely disagree and have 600rw, daily driven reasons (http://www.calibratedsuccess.com/pics/TurboLS3_new_MAF.JPG) why

[ringram]

There are plenty of others with much more rwhp running mafless which can also do some proving of their own.
I see no logical reason why mafless should be ruled out other than easier airflow modelling with the maf table. Save butchering the whole ECU calibration just because you want to keep the maf.
Dodge dont seem to have any issues running millions of vehicles mafless!?

[eficalibrator]

Does your 600 RW DD reasons MAF read reasonably smooth with the split feeder pipes coming into one? Is that a 100mm pipe or 90mm that the MAF is mounted in? Looks like a 90 in the pic as smaller than TB, so just checking.
Yes it's ~90mm (3.5" stainless pipe). You'll notice a few things in the photo:
1) I maximized the amount of constant area pipe upstream of the MAF to reduce changes in velocity along its length.
2) The bends upstream are relatively gentle and directly opposed where they merge to reduce turbulence. Both pipes feed an equal amount of air/boost due to balanced system.
3) The MAF element in perpendicular to the plane of the last bend upstream of it (Where the tube bends over the top of the radiator core support), so that it's not biased toward high/low velocity from that bend.
4) Final noise from the 90mm body was significantly better than the original 103mm unit I tried (http://www.calibratedsuccess.com/pics/turbo_ls3_resized.JPG) where there were more pronouced changes in area. That unit had +/-300Hz noise and was basically unusable in this particular application. The smaller area gave more consistent readings and I only hit ~11kHz @ 67lb/min actual flow with the current piece. This leaves all kinds of headroom if I get silly later.


There are plenty of others with much more rwhp running mafless which can also do some proving of their own.
I see no logical reason why mafless should be ruled out other than easier airflow modelling with the maf table. Save butchering the whole ECU calibration just because you want to keep the maf.
Dodge dont seem to have any issues running millions of vehicles mafless!?
I'd wager that there's more actual "butchering" going on where one changes the entire operating system (PCM Code) to support 2bar+ VE tables than just recalibrating existing factory tables using simple physics and math. Dodges were engineered to run completely in SD from the factory.

[jnjprfrmnc]

I managed to get the car tuned ok they moved the MAF sensor to the end of the straight section in the charge pipe before the T/B and that calmed the signal down some it's still not perfect but will do till they make a new pipe it made 600/630 RW and only seen 10.4k Hz here is a link to the car http://www.camaro5.com/forums/showthread.php?t=45224 the customer seems to be happy for now and he will get the updates as they happen hopefully I will get it near perfect for them.

[gmh308]

Ok thanks for confirming that. Was the +/-300Hz noise all steady state from simply having the 104mm pipe that close to the TB? What sort of noise figure do you see with the 90mm pipe? Most recent factory based 90mm setup we looked at was around +/-140Hz steady state (+/- 1.4%).

Where are the turbo/s on the engine? :) :) :) Nice.


Yes it's ~90mm (3.5" stainless pipe). You'll notice a few things in the photo:
1) I maximized the amount of constant area pipe upstream of the MAF to reduce changes in velocity along its length.
2) The bends upstream are relatively gentle and directly opposed where they merge to reduce turbulence. Both pipes feed an equal amount of air/boost due to balanced system.
3) The MAF element in perpendicular to the plane of the last bend upstream of it (Where the tube bends over the top of the radiator core support), so that it's not biased toward high/low velocity from that bend.
4) Final noise from the 90mm body was significantly better than the original 103mm unit I tried (http://www.calibratedsuccess.com/pics/turbo_ls3_resized.JPG) where there were more pronouced changes in area. That unit had +/-300Hz noise and was basically unusable in this particular application. The smaller area gave more consistent readings and I only hit ~11kHz @ 67lb/min actual flow with the current piece. This leaves all kinds of headroom if I get silly later.

[gmh308]

I managed to get the car tuned ok they moved the MAF sensor to the end of the straight section in the charge pipe before the T/B and that calmed the signal down some it's still not perfect but will do till they make a new pipe it made 600/630 RW and only seen 10.4k Hz here is a link to the car http://www.camaro5.com/forums/showthread.php?t=45224 the customer seems to be happy for now and he will get the updates as they happen hopefully I will get it near perfect for them.

Very nice setup on the Camaro 5 site. :cool: What turbo is it?

[ringram]

I'd wager that there's more actual "butchering" going on where one changes the entire operating system (PCM Code) to support 2bar+ VE tables than just recalibrating existing factory tables using simple physics and math. Dodges were engineered to run completely in SD from the factory.

We are in the E38 forum where this comment is invalid. OEM calibration supports 3bar VVE. So does the "butchering" now apply more accurately to the MAF user?

Though accepted the 09 ECU's seem to have fixed some earlier oversights with regards to limitations etc. However at the extremes MAF response is non linear therefore less accurate at very low (relatively speaking) and very high airflows.

It would seem to me that we have 2 means of determining airflow. One easier to model than the other, but ultimately both valid. Each with their own pro's and con's

[gmh308]

We are in the E38 forum where this comment is invalid. OEM calibration supports 3bar VVE.

Maybe it was a reference to the competition's approach to boost and VE...:angel_innocent:

[eficalibrator]

Ok thanks for confirming that. Was the +/-300Hz noise all steady state from simply having the 104mm pipe that close to the TB? What sort of noise figure do you see with the 90mm pipe? Most recent factory based 90mm setup we looked at was around +/-140Hz steady state (+/- 1.4%).

Where are the turbo/s on the engine?
Yes, the large signal noise with the larger MAF housing was in steady state, 3rd gear, on a loaded dyno. The issue was more due to the significant change in area from the smaller "Y" piece into the MAF housing than the proximity to the TB. Keeping the smaller MAF housing meant a more consistent cross-sectional area approaching the metering element, which gave a more consistent (noise-free) reading. Since the 3.5" tube only hit ~11kHz at the top end, there was no need to go larger in an effort to support more measurement range.

The turbos are mounted low and back, next to the oil pan. They're basically in the stock cat location. There's a scavenge pump system to return the oil back to the block above the level inside the pan (which is above the turbos' actual drain height).


We are in the E38 forum where this comment is invalid. OEM calibration supports 3bar VVE. So does the "butchering" now apply more accurately to the MAF user?
Perhaps not, since my 2009 e38 also supports the full MAF range without scaling. ;) I also use a 3bar MAP Sensor on my car, with the VVE enabled above 1 bar. I guess one's definition of "butchering" is relative, as I don't consider a single straight multiplier applied across a wide range of cal tables to be "butchering" in the same way that completely removing some factory tables in the code to make room for other larger tables does in some of the custom OS's.

However at the extremes MAF response is non linear therefore less accurate at very low (relatively speaking) and very high airflows.
That's the beauty of a MAF sensor. It's intentionally non-linear (exponential, actually) so that it has higher resolution at low flows and trades that resolution for range up top. Properly applied, it's a great solution as long as you have laminar airflow across the metering element.


It would seem to me that we have 2 means of determining airflow. One easier to model than the other, but ultimately both valid. Each with their own pro's and con'sAdmittedly, any MAF is prone to some degree of reversion noise given a large enough pulse. Large cams tend to make this worse, which is why many in the aftermarket have lost their faith in the MAF. The problem is usually more one of the engine hardware and installation than the fundamental operation logic inside the PCM itself. I still maintain that the best solution on a GM vehicle is to keep BOTH parallel airpath estimates working properly and allow the factory blended logic to work as designed whenever possible.

[gmh308]

Yes, the large signal noise with the larger MAF housing was in steady state, 3rd gear, on a loaded dyno. The issue was more due to the significant change in area from the smaller "Y" piece into the MAF housing than the proximity to the TB. Keeping the smaller MAF housing meant a more consistent cross-sectional area approaching the metering element, which gave a more consistent (noise-free) reading. Since the 3.5" tube only hit ~11kHz at the top end, there was no need to go larger in an effort to support more measurement range.

The turbos are mounted low and back, next to the oil pan. They're basically in the stock cat location. There's a scavenge pump system to return the oil back to the block above the level inside the pan (which is above the turbos' actual drain height).



Ok thanks! Nice turbo setup. '09 Corvette with stock pistons? :cool:

[ringram]

Admittedly, any MAF is prone to some degree of reversion noise given a large enough pulse. Large cams tend to make this worse, which is why many in the aftermarket have lost their faith in the MAF. The problem is usually more one of the engine hardware and installation than the fundamental operation logic inside the PCM itself. I still maintain that the best solution on a GM vehicle is to keep BOTH parallel airpath estimates working properly and allow the factory blended logic to work as designed whenever possible.

Yep Ill go with that :cheers:

[eficalibrator]

'09 Corvette with stock pistons? :cool:
Yes. I've done hundreds of forced induction engines with stock bottom ends, including hypereutectic pistons before. You just have to remember that two things kill engines, knock and RPM. As the calibrator, you have control of both. ;) (Well, barring any mechanical over-rev from a downshift at least)