if he has 10psi and others running 7psi have seen their MAF max out at about 5Krpms, his is probably maxing out earlier.......since the S/C is RPM dependent, the point at which the MAF maxes out should be too, regardless of throttle position......i know you're thinking something MPH, what concerns are you having?

 

Hopefully not ECU related?

 

So when you are NA does the MAF get maxed out to go to open loop or does it go with 100% throttle also? If NA does not max the MAF then how do you get open loop NA? Does open loop depend on either MAF max OR full throttle? What led you to the conclusion that MAF max means open loop?

 

this is a problem because the MAF has limited air-measuring abilities, and it can't read boost. MAP sensors read positive pressure, and thus the ECU knows that there is more air being forced into the cylinder, and thus it needs to spray more fuel.

On the stock ECU, when the MAF is maxed out, the ECU has no way of determining how much more fuel is needed. That's why the various kits out right now have various piggyback bandaid solutions to this problem. I would even say the Rebic EIC is somewhat of a bandaid solution, although better than others, since it uses a separate MAP sensor to read boost and determine the appropriate amount of fuel to spray.

I didn't know that the ECU goes open loop when the MAF is maxed out, but even if it does, the stock ECU (without any modifications or piggybacks) never sprays enough fuel to handle high boost.. it's limited by too many factors (MAF, injector size, fuel pump size, etc, etc)

 

Yes, this is what's happening.......usually MAF related errors will be indicated by a CEL.....no CEL has been thrown, although maxxed MAF's have occured, and the car doesn't go into failsafe mode either.......the car runs great.......that left only 2 options........either the ECM continued to make calculations based on the maximum amount of air it could sense and the readings on the O2 sensors, or it switched to open loop.......the last time 12SecZ was flashed he posed this question to Tadashi at Technosquare.......he confirmed that the ECM goes into open loop when the MAF gets maxxed out

we still don't know for sure that all FI Z's are getting maxxed out MAF's, but we know of 2 that have definitely seen this on their dataloggers.....like with anything else, there are variables here (i.e. variance in sensitivity of MAFs that have had a slight bit of air filter oil contamination, electrical connections, etc.)........but so far, it appears that the MAF goes blind at about 5Krpms on 7-pound supercharged Z's

 

On my car at 100% throttle I am never N/A and it's a very fine line between N/A and FI on my car sometimes only 2k rpm's or less because I do not have that Aeromotive Box saying the boost will kick in at x rpm's (4k) , I removed it.

If your question is would a stock ECU max out on a N/A car and go into open loop mode the same way a reflashed one does then my answer is if it saw too much air yes it would.

On lower RPM's or N/A I am closed loop when not maxxed out.

I can not tell you exactly when my car goes from closed loop to open I think it would vary from car to car and probably occurs earlier on my car like EJ said because I have an A5T and EJ has ridden shotgun several times and it when the boost kicks in it just HAMMERS straight to 9-10.

Allot of it is how you drive though so in normal driving mode I would say about 5k on my car, in hammer down mode or WOT probably earlier.

The reflash adjusts the TBP and I am told the repositioning is more beneficial to A5T's than 6MT's.

When the MAF is maxxed out it is not an issue that is causing my car problems or symptoms. If I had to guess I would say (and based on test drives with Tadishi) it was about 5k but that was at 11 PSI and now I am at 9-10 so it may have changed.

I hope some of this helps you for whatever reason you may need the info for. Now maybe someone will help me on this FPR fix?

 

I think azrael and I are on the same page when I ask then, If it goes to open loop at 7 psi and 5K, how does the ECU know how to regulate fuel if the MAF is no longer reading variability but rather its maximum capability? You know, for anything over 5K or 7 psi which are obviously numbers you and many others turn.

 

Fly by z, a MAF is a Mass air flow sensor. Flow, It measures the flow through it. This is fine for a NA car it can determine the volume of oxygen coming in and how much fuel it can burn with the supplied oxygen. A MAP Sensor is Manifold absolute pressure. With a MAP sensor the ECU can calculate the amount of o2 and the required fuel. Map sensors come in the flavor if 1 (14.5psi) ,2 (29 psi) , and 3 (43psi) bar. When tuneing with a map sensor you can have the ECU supply a defined amount of fuel by varying the injector pulse for any give amount of pressure in the intake.

I think once I rebuild the motor i'll go standalone with the Accel DFI or the AEM standalone unit. The AEM is developed my ProEFI who was purchased by AEM so don't flame me! I hear it's a good EMS. That and some 60lb injectors should work out well.

 

If?

.... sigh....

I'll just drive my car, it runs great. Let me know when you decide if it does or doesn't.

What about my FPR questions no answers eh?

 

It doesn't.....it supplies the amount of fuel that's programmed into the open loop map in the ECM for a given RPM........but that's not at 7psi........7psi isn't reached until closer to redline

 

Why did you post this info?



So, EJ, is it not dangerous or anything to hit a preset recognition limit and then keep forcing air past that limit with no way to see how much air is going in/what pressure (4 ETX)?

Also, 12sec, I am in no way doubting that your MAF goes open loop. I am, however, asking about the implications of it. Please don't let this discussion go awry. Also, if the car runs fine up and down the revs and AF readings, etc. with a stock MAF going to open loop, what would be the point of a MAP on the Z. Obviously, according to your car, an open loop MAF is all that is needed. Out of all the FI applications so far, I think yours, while not the least expensive, uses the most common sense/simplicity. Except for building the motor to maximize the Procharger, yours is the route I want to take so far. The Procharger is a simple system to push more air, the injectors/fuel pump/ECU tune is a simple way to push more fuel. As long as it works... I am just trying to see consequences. Please understand the side I am coming from. Yours.

 

lol,

no problem. , I do not think there are any implications. We can specualte and theorize but my real world experience to date is there isn't anything negative about open loop with CAN.

I know you are considering an N/A flash and plenum so I know where you are going with this so at what point would there be a symptom?

To me it seems it would be immediate but it isn't on more than one car. The answer is out there somewhere we will just have to hunt it down as usual.

 

I added some stuff. Yes I am going with the plenum and a temp ECU tune for NA until I build the motor and add Procharger.

 

Zedd has my same setup and Ultimate Z did his car and they could talk all day about this scenario, I followed Zedd's lead after seeing his worked.

I agree about the forged internals I should have done that first but live and learn.

I can call Danny at TS or you could, he was open to talk about maxxed out MAF stuff and open loop info with EJ and I and Ultimate Z and ZED know allot more about the maxxed out MAF scenario than I do.

I am glad my system works though, timing and fuel. I tried the RC 440's first and they didn't work and so did ZED so you can sort of form a pattern off of two cars rather than one. Mine and Zed's (in Chicago) both have reflashed ECU's removed the Aeromotive, added the 380's. He doesn't have the Crawford or Cat pipes but he has a Nismo Headers with a Stillen exhaust and drives his car harder than me (6MT) he once told me on the phone that after flashing with the injectors he got his car running so hard he got it to kick it's asz end out in 3RD GEAR!

It's basiclly the tuner kit ATI talks about self tuned with the timing problem fixed and more fuel added, kinds simple when you look at it that way. Guages have played a big role for me too.

 

So, really, a MAP is not needed? Is this true on the Z in particular or do many cars work this way? Also, who has the Tuner Kit for the least amount? If I just buy the Tuner Kit, is all that is missing the FMU or are other things absent as well? I assume the Tuner kit includes all of the mechanicals? Thanks.

Also, just in case something comes up later, is there a way to make or buy a MAF that has a higher limit than the stocker?

 

There is a mod you can do to obstruct the front of the MAF it's a hack that Maxima's guys are doing N/A.

You basicly block the MAF so it reads less air. No I do not think we need a MAP, neither do the programmers because when the MAF maxxes out it goes into open loop. At what point? I don't know just at the point where it can't read anymore air.

TT's didn't have a MAP did they and they ran boost for a long time?? Would have to look into that aspect.

As for the Tuner kit's it can save you about a grand, I am not gonna throw out Vendors but I know who gave me and EJ the best price. I have heard that the Tuner kit is 800 less, I bet a smooth talker could save a grand on the tuner kit.

It includes the FMIC too, it incldes everything except the Aeromotive which I cannot give awau for 150.00 bucks even if I include the stock injectors. That should tell you something of the "extra's" values you would be missing out on.

Tuner Kit $3600.00, I bet it could be done. Then larger injectors and a flash, that's it! Plus guages. The Ultimate Z car is running 7 pounds and is much richer than I am (therefore probably safer.) What are your goals MPH, 7 PSI if so you wouldn't be sweating this fuel pump and FPR like I am, I am just being cautiuos though, if I go off my EGT guages I have been watching for months then I am at safe levels.

There is no larger MAF I know of, my suggestion was have someone make one ASAP, rather than trick the stock one. I would buy it!

 

I called someone to confirm some of this stuff MPH.

No changes are made to closed loop mode in reprogramming an ECU "you cannot touch that."

When does a N/A car go into open loop?

"At WOT."

Why doesn't my car need a MAP?

"Introducing a MAP would be to control an auxilary pump or sense the boost or control larger injectors."

MPH, and others, a reflash can also do this.

So bottom line the reflash sort of acts like a MAP.

When does an FI car go into open loop? Well this is grey because it doesn't go by throttle position anymore it's in the altered program.

For the record I found out today from who I consider to be "the source" of flashing our ECU (he lis leaving for Japan this weekend to go learn even more) that I am running the "9 lb program."

My boost, my injector size and pulse, are being controlled by the reflash much like a MAP would.

"You do not need a MAP" he said because "we have altered your programming. "

I hope that makes sense it does to me, it also explains why I am running richer since dropping from 11 PSI to 9 PSI.

I get the feeling they would love someone to buy a fuel pump and FPR and run a line up to the front to tell it when to regulate and then they would have a higher program.

Right now it sounds like, and I am about 99.5 % sure of this, that our fuel sysyem maxxes out at 9 lbs and that is from the man who brought the box over here originally and writes the programs that seem to work very well.

I wish I could change another tooth, maybe I will call ATI and see is they have a 24 or something, might be a safety buffer and drop me to 8-9 rather than 9-10 actually the more I think about it the better that plan sounds because the "9 PSI program makes plent of fuel for your setup, you do not go lean."

I still wanna look at a spark plug though but I need to be exact 9 PSI not over and right now I am, so close and yet so far!

EDIT ADD: I need to look at a plug, not a pump. I want to change the smaller easier to get to pulley. You do not have to take the bracket off for that one.

 

Why did I post that?
"I think azrael and I are on the same page when I ask then, If it goes to open loop at 7 psi and 5K, how does the ECU know how to regulate fuel if the MAF is no longer reading variability but rather its maximum capability?"

To explain the fact that the Z in it's stock from cannot support boost. It need a sensor and the proper electronics to control a fuel system capable of running ANYTHING over 14.7 psia. It's that simple. Maf is no good for FI and we need a standalone or piggyback fuel computer to properly boost this motor. Even the greddy system uses a 'Hack' that I will not be using for very long.

The ATI kit uses the WORST possible way to increase the amount of injected fuel. Not only is it rising the fuel pressure, it's doing it with an electronic pump. YEA, I'll pass on that. No wonder so many people are popin motors.

 

My ATI kit doesn't work " the WORST possible way " *or* need a MAP for reasons explained. People are Popping motors because of timing / detonation not MAF's and MAP's.

 

on our car the MAP is not needed, since it reverts to open loop when it hits MAF max......i can't really speak for other cars, but i've heard of CELs occuring on other forums

the MAF may be able to be given more sensitivity through minor mods if this ever becomes a problem