XxJMF02xX

Also from what I understand from what I've read here not all MAF systems have a MAP sensor. So no I don't get it. You seem like your real caught up in trying to prove me wrong here. The point of the forum is to learn things from each other not to try to discredit everyone else.

jimlab

You seem to be grasping at every straw Kento drops, trying to save your unsupportable theory. Even Kento dropped the "inertia" line after he figured out what was going on.

FACT: The majority of MAF-based systems also have a MAP sensor.

FACT: They therefore have the ability to react just as quickly as a speed-density system to any sort of anomaly in airflow, because they have the SAME SENSORS.

You're obviously not learning anything.

Don't post in this thread again.

XxJMF02xX

if the majority of all MAF cars have MAP sensors then your right and I'm wrong. But why is it when you quote Kento your proving your point but when I quote him I'm grasping at straws. Seems a little wierd huh.

But most importantly....

DO NOT TRY TO TELL ME WHAT TO DO.

I'll decide where I post.

jimlab

Because he was CORRECTING you with that post. If you're right and I'm wrong, have you stopped to consider why Kento isn't supporting you? Why don't you ask him.

Well, you were warned.

XxJMF02xX

Kento isn't supporting anyone. He's not on your side or mine. He's just stating what he knows. And just what do you think your going to do to me. Everyone watch out no ones allowed to disagree with jimlab. Thats right didn't you know he knows everything. Give me a break.

FDNewbie

iTrader: (10)

As much as I'm tempted to grab a bag of popcorn and sit back, plz guys, I'm actually trying to see this thread go somewhere, not have it locked cuz ya'll are duking it out on the net lol. Exchange emails, and fill one another's inbox as much as you'd like, but can we keep stick to the topic on the thread? Thanks

XxJMF02xX

Sounds reasonable Newbie. But seriously Jim all I'm trying to say is lighten up. People are gonna have different views/opinions somtimes. Some right and some wrong, but not everyone who disagrees is trying to start a war.

J.S.J

I know barometric values are needed to form a base and I also think don't know for sure but if you start at the top of a mountain and descend without shutting off the engine and restarting you will not have the best set of maps going. I am talking about a large difference in altitude. Example 6k feet to 1k. You might not notice it but its a factor. I work for G.M. dealerships as a tune up and drive-ability tech and this has been mentioned. The hole thing about how a O2 sensor gets involved is sometimes misunderstood. We know its for emissions and thats normally good for the best mileage but theres a much smaller window where its voice is important. Most any acceleration of the engine weather rapid or not is not a place where the O2s voice is herd. At idle, cruse (not at 100mph) is where its input is used most. I know we are talking about map/MFA however its the other system sensors we need to understand as well. Seems to me someone has to do the r&d using a F.I. system from another engine. I would think with a turbo system it would be essayer to convert because we have a wider range of vacuum/pressure then N.A. systems. Maybe its as simple (Simple HaHaHa) as converting a pressure sensors algorithm (+17 inches of vacuum to +25 pounds of pressure) to a language which could be crossover. I can't see how its not now working except for the factory's programing of the system cut off points. Well its a project of interest at least using a keyboard. John

Kento

Negative, because the margin for error with a/f ratios and ignition curves in a forced-induction engine is much smaller. A NA engine won't ingest internal components just by running a little lean or a little too much advance.

It's not the language of the sensor you'd have to convert; they're either analog (voltage) or digital in their communication. It's the ECU (and a more powerful--read: complicated-- one at that) that you'd have to adapt to the needs of a totally different engine.

jimlab

Ask JoeD or JRK or RotaryWorks... oh, that's right, they can't post here any more.

XxJMF02xX

and whys that?

jimlab

Figure it out, genius.

XxJMF02xX

look man u wanna get me banned then ill just register again with a different name. But forget that, couldn't you tell from my last post i'm trying to let this go. You really need to chill out and let it go. The arguements over.

J.S.J

Again not disagreeing in general, however G.M. used a maf (hot-wire) back in 1985. That was using an E.C.M which by todays standards is a flasher unit. It did the calculation's well. I didn't mean taking a piston engine its fuel curve and ignition curve and placing it on top of a rotary system. The thought was more abstract in nature. At 7k and W.O.T theres not a lot of adjusting going on. Lots of fuel and not too much advance. Now when you start to get board with the power and want more is where things can go to peaces. Everything must be tuned. Again in 93 most all systems were OBD 1 but I see Mazda got an exemption.

KevinK2

The fairly modern saab turbo T7 ecu (likely bosch motronic) uses both systems, but per this link, the manifold pressure transducer is only used for quick transients, which suggests that the map system does have faster effective response.

Other problem with MAF systems is the "volts gain vs flow gain" drops off at the high end of the curve ... ie going from 4.5 to 4.6v output relates a very large flow change. This suggests as power is increased in a MAF based system, the maf sensor will be pushed into an less accurate part of it's control range.


http://www.users.qwest.net/~lhagan/T...scription1.htm

jimlab

Compared to what? A MAF-based system with no MAP sensor?

If we're going to split hairs, then yes, a MAF-based system without a MAP sensor would likely react slower than a speed-density system... which is totally irrelevant, because if it doesn't have a MAP sensor, it's not turbocharged and wouldn't experience boost spikes anyway.

KevinK2

Your assumptions are:
1) all turbo MAF systems have MAP sensors
2) If a MAF system has a MAP sensor, it's used to control transient fuel needs.

Both are wrong. Bosch LH MAF turbo ecu's in the 90's didn't use MAP sensors.
As late as M2000, motronic 4.4 used in volvo 850T was MAF, with a MAP sensor
just for boost and cold start control.

http://www.volvoclub.org.uk/tech/fue...254Tengine.pdf

Just having a MAP sensor on a MAF system doesn't mean sh*t unless you know exactly what it is for.

jimlab

Reading intake manifold pressure?

Well, I stand corrected. How long did you have to dig for that, and are boost spikes a big problem for Volvos?

KevinK2

not long, having some history with saab and volvo bosch systems.

I do think the best MAF system is as you assumed, with true MAP assistance, which is the saab T7 ecu I linked before. Likely others are doing this now.

johnchabin

iTrader: (2)

Sorry if this is a repeat. I read the last 14 pages pretty quickly.

Do you plan on using 2 MAF sensors or splitting one large (90-100mm) intake between the 2 turbos? I don't think post-intercooler installation is an option (although would be convenient). MAF sensors are not typically oil-tolerant.

How will you handle prespool air that doesn't make it to the intake manifold?

Seems to me a MAF sensor used to compliment the existing systems makes the most sense. It could be used for data collection initially, then incorporated into the system. Not an easy task.

Good luck.

Starx7

I just read most of the last 15 pages excluding the troubled spots, and got lost some where along the way. I think now would be a good time to recap. Have we come to any final decisions, or are we still thinking that the volvo, saab/ 2 MAF sensor / MAP sensor ? Speed density system will work best?


Also my two thoughts. AEM has thier ems, which I believe can be set up to add sensors/ switch sensors. It is also extremely tunable. They also just released a version of it that is a blank slate, that is meant for any car. Obviously someone would have to do lots of tuning, but the ease of this system would probably outweigh the effort. Also, once someone got it set up right, thay can probably give it to others with the EMS. This sounds like the best choice. Just my opinion though.

M