MAF vs MAP(SD) tuning

[yomny]

For those who know or have experience with these two different methods of tuning, especially in forced induction applications. I've tried both tunes and although i like the power offered by the map tune i think is not something i could live with on a daily driving scenario. Compared to the maf tune vehicle, the MAP tuned car feels erratic below boost or 4k rpms. The car doesn't feel smooth when applying throttle progressively, if gas pedal is pressed suddenly the car jerks. Feels like driving a car in sand. Anyone with more knowledge could chime in and explain why this could be the case. The cars don't have any mechanical problems or any other factors that could potentially give one the advantage. I feel like the car on MAP tune has to be pushed harder to move, feels like it bogs up to about 40% throttle then surges, the MAF tuned vehicle just feels like it builds boost smoother, faster, easier... Anyone with a map tuned car could chime in and relay your experiences and if you've ever ran a Maf tune to compare. Thanks

[yomny]

To add to my own investigation or quest for knowledge, I read on other forums that like Cobb ecutek uses a hybrid mode of maf and map and if not done perfectly correct it could be abrupt.

"Of course they do for quite some time now... The difference is that cobb calls it hybrid mode and it is merely a switch that clamps the maf via set thresholds and then SD takes over fuel calculations. If it is not tuned correctly it can be quite abrupt. The OS community takes a better approach in my opinion though, They call it maf blending and it allows you to phase out the maf and phase in SD by having both calculate fuel simultaneously as you transition from one to the other and you can define the percentage between them. It is a 3D table with PSIR along the X axis and RPM along the Y and the values represented in percent of maf blending. Very simple to understand once you see it"

[350matt]

Thats right ECUtek has a hybrid mode so you can run a mix of MAP and MAF load inputs

I'd say the MAP tune needs some work as it should be possible to get to it to drive smoothly
OEM's have used speed density for years so its not a bad method

[yomny]

Originally Posted by 350matt

Thats right ECUtek has a hybrid mode so you can run a mix of MAP and MAF load inputs

I'd say the MAP tune needs some work as it should be possible to get to it to drive smoothly
OEM's have used speed density for years so its not a bad method

Thanks for your input, I know map has been used for many different oem applications. I think the drivability, transitions aren't yet smooth enough on ecutek to compare to a maf setup.

[Xero-Limit]

Originally Posted by yomny

Thanks for your input, I know map has been used for many different oem applications. I think the drivability, transitions aren't yet smooth enough on ecutek to compare to a maf setup.

This was exactly our finding and why we did not go full SD. Yes, it is easier from a tuning standpoint because you don't have to customize for each car to such a degree. The speed density based tune will adjust quite well completely regardless of the setup as long as the injector value is correct. However, low speed drivability is exactly how you describe. The reason for that is that the compensations for throttle tip-in are not nearly as refined under speed density. At high loads it is not an issue at all. But at low/mid throttle inputs it is less than ideal. We've converted all of our JRSC tunes to use strictly MAF for fueling, and only on the higher boost kits do we utilize hybrid SD (turbos in particular with open BOVs behind the MAF or > 350whp). We still use a MAP based timing map though, this is more effective than using load calculations given the confines of the stock ECU.

[yomny]

Makes sense, thanks for the explanation @moto-mike. Didn't know the difference was so dramatic, my car feels like it drives on marbles as opposed to the other one driving into a sand bank, till it hits boost then it surges. You've got mail by the way.

[ztan]

I'm using hybrid SD: MAF below 180 g/s, blended MAF/SD up to 240g/s, full SD above.
Low speed driveability is stock, needed the SD higher in the airflow range to prevent a capped MAF. I selected these ranges based on what I was seeing comparing MAF calculated airflow to SD calculated airflow - the variations were much smaller at airflow >80 g/s where you're mostly WOT. See my thread on open source hybrid SD solution.

Takes quite a long time to dial in SD for driveability, then you need to dial it in again every time you make an adjustment to anything that affects volumetric efficiency - intake, exhaust, AVCS...

[yomny]

Originally Posted by ztan

I'm using hybrid SD: MAF below 180 g/s, blended MAF/SD up to 240g/s, full SD above.
Low speed driveability is stock, needed the SD higher in the airflow range to prevent a capped MAF. I selected these ranges based on what I was seeing comparing MAF calculated airflow to SD calculated airflow - the variations were much smaller at airflow >80 g/s where you're mostly WOT. See my thread on open source hybrid SD solution.

Takes quite a long time to dial in SD for driveability, then you need to dial it in again every time you make an adjustment to anything that affects volumetric efficiency - intake, exhaust, AVCS...

Awesome work indeed lol most of that stuff flew right over my head. Looks like it's a matter of fine tuning the low throttle-part throttle drive ability, it's detailed work and could be done apparently but maybe not easy to do for distribution like a regular ecutek flash. More hands on tuning would be needed to get it right. Maybe someone would make full use of this on the ecutek software.

[350matt]

I'd say Ztan is right

use the hybrid function to blend between the MAP and the MAF and you should get the best of both

[aagun]

1- MAF FOR CLOSE LOOP
2- MAF FOR LINE SPEED NORMAL DRIVE
3- MAF FOR CRUISE CONTROL
4- MAP FOR BOOST
5- MAP FOR BOOST
6- MAP FOR BOOST
7- MAF SHOULD BLINKED UNDER BOOST

[yomny]

Originally Posted by 350matt

I'd say Ztan is right

use the hybrid function to blend between the MAP and the MAF and you should get the best of both

This i would do if i had a clue as to how to go about it. I'd say have to use an open source flash/read software and an obd2 cable to flash the software. I use ecutek so i'm at the mercy of tuners don't really have enough skills to develop my own tune even less tinker with hybrid setups.

[350matt]

might be worth ringing round a few tuners I'd say to see if any offer a developed Hybrid MAF / MAP setup

could Delicous tuning help?

[yomny]

For those with Speed density(map/maf) software experience

Wondering if there's anything in map(speed density) or hybrid mode of tuning that may cause a turbocharged car to feel supercharged. May be hard to explain so I may have to exaggerate on the butt dyno feelings to get the point explained. There's a certain surge(spool) with turbo that even at constant or slightly progressive throttle application you feel as if the car is being pulled forward as the turbo spools.
With the speed density(hybrid) tune, the car feels NA with more power of course, under light to just under mid throttle then a plateau feeling(for the next 10% increment in throttle) and then boost hits(no surge, feels like off boost, on boost) but is missing that spool characteristic. I know this isn't in my head because im comparing it with another tune which feels just as a turbo spooling car should.

Please keep in mind all these percentages and numbers are hypothetical as I don't have any data, just driving feelings.

[350matt]

I'd say that the handover period in your MAF to MAP needs flattening off/ smoothing out as it sounds like the MAP values aren't smoothly tapering to mathc those of the MAF values