shayrgob240

Why is it desirable to omit the MAF for the MAP to take its place? In other words, why is it better for the sensor to sense pressure than for it to measure mass? Is the MAP more reliable and therefore tuning's more accurate? And I'm obviously asking about when you have a standalone. THanks in advance.

chmercer

maf is more accurate but in high boost applications you cant very well have like 6 inch intake piping to accomidate a large enough maf.

scottie

MAFS are known to be more reliable because they rarely go lean (unless you push beyond their HP rating). MAPS can go lean if not tuned correctly but pressure it more accurate reference than air flow. I would say that if you dont plan on going big there is no need to go with a MAP.



Scott

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Josho

Old thread but is there anymore info on this subject? Ive been reading up on this on other sites but not much has been mentioned on here. I would like input from some of you guys, hopefully somebody who is actually running a MAP sensor. I have an AEM EMS and was just curious if converting to a MAP sensor is worth the effort? Im not going for a large amount of power, maybe 350whp with my GT2871.

240Shwag

Don't bother. Stay MAF.

Josho

Im wanting a little more informed response. I want to know what the gains are strickly for an sr20det. Pro's an cons of both of them. Why its better to run one or the other.
I dont want to make my decision because you told me not to do it, I would like to weight out the pro's and con's and decide after gathering the good and bad for both set-ups.
I appreciate the response but could you tell me why I should stay with my MAF rather then converting to MAP?

revolutionz_s13

MAP will give you a little more flexibility in tuning, as the sensor is mounted in the intake manifold. You can vent your bov to atmosphere easily, and boost leaks wont affect the car as much if you have a pipe pop apart. Other than that, when you put the intake on the turbo, you dont have to worry about a maf being so far away from the turbo or anything like that, just put the filter on the pipe and be done with it.

Josho

All that sounds great! Which is why Im confused about a lot of people saying dont go with a MAP, keep the MAF. Is that from lack of experience/knowledge or do they know something that others dont know. MAP sounds to me like the better choice as long as Im going with a standalone. I hear its also easier to tune the AEM EMS if you have a MAP. All the pro's seem very good about going with a MAP... Is there any bad side affects?

Sil-Eighty SE-K

With map you lose load point resolution once target boost is hit
Whereas maf will still have resolution throughout the rpm band as airflow increases (pressure remains constant at target)

Maf is also easier to tune there is no base map and correction map.... just correction
It'll run out of the box on a base map much better as well

Unless you're maxing out any mafs available to your setup (and you can run 600hp with a z32) there is no sense going to a map based setup IMO
And even then you can have custom mafs made to measure pretty extreme amounts of airflow

They say the drawback of mafs is a restriction in the intake... True with a stock mafs that bottlenecks... Run an rb25 or z32 and there is no restriction they are 80-90mm just like your inlet pipe

I have a map based PFC on one car and mafs based on another so Im familiar with both

Just my $.02

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Originally Posted by JTunedMotorsports get off the thread...no one cares...

Josho

I see your points aswell. Would you still run a MAF in my situation? Considering Im running an AEM EMS. I've read that AEM is set-up for MAP and makes it easier for tuning.
I guess what Im trying to do is seperate the good/knowledgeable info from BS info.

Thanks

ILoveJDM

one less important note, but a really good one,

if youre far away from home and pop the intercooler piping right off and have no tools, you can still drive home on map. where as with MAF youre SOL and have to call a buddy etc. especially if youre piping is complex and has the couplers behind body parts etc etc

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Josho

Have any of you guys converted from MAF to MAP? If so, PM me please.

usdm180sx

Having a filter and intake pipe that goes straight to the turbo is cool.

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Josho

I think so too!!

Corbic

MAP all day long.

lflkajfj12123

King of Dope Total Knockout

Corbic

Not to mention you won't have any issues with BOVs and ICs.

JSimpson

Can a stock nissan ECU read a MAP sensor? Like an AEM 5 or 3.5 bar sensor...?

SLiDe_WaYz

No, don't even think a rom tune can run a map.

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JSimpson

Didnt think so. MAP FTW on an AEM EMS. Anything else, keep it simple: MAF

lflkajfj12123

no way in hell

Emeru

Make sure if you stay MAF you vent the BOV back to the intake, if not when the BOV opens the ecu has read all that air let out and will dump all the fuel for air thats not there.

SomeoneWhoIsntMe

the stock ECU uses airflow to calculate fueling. you cannot replace airflow with pressure in the ECU's equations and come out with the same fueling curve.

SLiDe_WaYz

Not sure on that one, I have a atmospheric BOV ( GReddy Type R ) and I dont run rich or lean when im under boost from it opening or closes. Does it vary on BOV types ?

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slowvia

Is there anyway to account for that in a tune? Ive herd that you can minimize the problem, but not eliminate it completely. Ive heard people talk about it before, but Im not sure how credible they are.
And if I remember correctly, MAF is much more user friendly, MAP's require tweaking when you change other things on the motor, whereas MAF's are pretty straight forward. Then again I havent really dealt with any of this so Im kinda just blowing it out my ass

SomeoneWhoIsntMe

An atmospheric BOV dumps a volume of metered air out of the inlet tract whenever it opens. that volume of air leaving what is supposed to be a closed system will throw the ECU off - it has no way of knowing that that airflow has gone somewhere else than into the engine, so it still injects fuel at the AFR it's trying to hit at that point in the fueling map.

There's not really any way around it, if you create a boost leak post-MAF with an atmospheric BOV, the car WILL run rich whenever it opens. The duration and severity of the rich spike depends on a whole multitude of variables (tune, BOV type, BOV spring stiffness, turbo, target boost, intake piping, etc etc), so it's up to you to figure out if it's a big deal on your car.

ILoveJDM

i used to have a MINES tuned ecu on an sr20. the never stalled after shift with maf or on decel, the tune was made so that upon decel, it would catch itsself on idle at 1100 rpms or so, and slowly come down to proper idle speed. this was with HKS ssqv, and no BOV at all.

after that i went from MAF to MAP with a powerFC, full-race gt30. saved time making intake piping, sometimes ran just a filter right on the turbo. had a greddy manifold and the MAP sensor screwed into the tapped holes on the bottom. couldnt have been easier than this. tuning it by myself too was also a cakewalk.

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SomeoneWhoIsntMe

It's possible to tune around it, but I expect it would be a bad idea.

You'd have to pick what condition you want to try and tune around... for instance, if you were concerned with getting the car as fast as possible in a straight line and you were convinced that bogging during gear changes was slowing it down, then you would log data while doing WOT runs going through a few gears. Now, I don't know which variables the base fueling map on the Nissan stock ECU is based on, but based on how it works on my WRX it's probably something like RPM vs. Load (calculated based on TPS and MAF). So, you'd figure out the RPM and Load where the BOV opens in your data logs, then take fuel away from that part of the map until you're at the AFR you want to be at under fast shifting, and the car behaves how you want under those conditions.

Problem is, the BOV being open has almost nothing to do with RPM vs. Load. During your tuning sessions doing WOT runs on the freeway, the car may behave much better during shifting, but if there's another situation that can cause the engine to be at the same RPM and Load that you just changed the fueling for, but NOT open the BOV, then you're fucked. If you were running 20% rich under shifts, you're now going to run 20% lean if the BOV doesn't open and you hit that cell in the fueling table.

I don't know how well I explained that, if it doesn't make any sense then let me know.

fliprayzin240sx

Both setup up has its pros and cons. I have run rom tunes and piggyback SAFC with Z32 MAFs. I decided to go MAP for the simple reason of not having to worry about getting a bad MAF again. Also, if I have a boost leak or crash the car where the piping are destroyed, I can still drive the car home no problem. The only downside of a MAP is if you have any boost leak, the car wont "let you know" it has a leak. On a MAF setup, if you have a leak, the car will run rich and potentially bog. On a MAP setup, the car will just feel slower.

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Corbic

You could did the BOV or just Recirculate it (ala stock style)...