Alfred at Tuning Tech, I was no implying the tune on the car was bad, sorry you took it that way. Fact is the dyno sheet shows 13:1 AFR's and that is lean. If the wide band on your dyno is off that far I'd suggest replacing it, no way in hell the sensor should be off that far from sniffing it at the tailpipe. If that is the case what do you tell a customer when you actually tune him for 11.5:1? The AFR's would realistically be in the 10.0's then and the car would be too rich. Our dyno uses a Innovate LM1, logs to the screen and is within .1-.2 AFR compared to a mid exhaust mounted AEM EMS wideband, this is anything over 2,000 rpm or so. Below 2,000 rpm there isn't enough exhaust flow to get a perfectly accurate reading. In a case that I do need a good reading that low (car doesn't have it's own wideband) I will install our LM1 sensor into a bung in the car instead of the tailpipe. Anyway, I wasn't cracking on the tune or AFR's. There are many ways to tune, I assumed whoever was tuning this particular car (did not know you were Alfred) felt leaner AFR's and less timing was a better way of doing it.

On page 8 it was asked about running a stroker, GT37 etc. and shooting for 600 whp. My suggestion is AEM EMS. No way I'd consider a reflash for such a combination. There is a post I just made tonight here on Engine/turbo/drivetrain about that exact combination I just had on the dyno today. Straight 93 octane, 21 psi the car made 475 whp on our dyno. AFR's never leaner than 11.4:1. Tomorrow it gets tuned on 93/alky, going well over 500 like that. Then race gas for 600+ I hope.

 

MAFs aren't limited by boost, they are limited by mass airflow. Saying that the MAF won't work once you hit a particular boost level isn't accurate at all. The boost level where the stock MAF starts to lose counts is going to be different for every car.

Also, there are replacement MAFs available that work just fine for much more mass airflow than the stock sensor will measure.

If you instead meant that the stock ECU doesn't have table entries past an airflow per rev equivalent of 26psi, I'd believe that. But if you meant that, say that.

 

For curiosity's sake, what do the spare and bumber beam weigh?

 

Only until the next test in a year or two. Then he would need another receipt.

Getting those exemptions is actually very difficult in Massachusetts. Virtually nobody does it.

 

Dave and Alfred, jeez, you guys both have your facts wrong.

Dave, on run 85, the one you are referring to above, the AFRs never get above 12.6. I've attached an easier to read graph to show you. Even so, the tune I raced with is represented more accurately on run 86.

Alfred, you refer to the AFRs as if you stopped tuning on run 85. In fact, you adjusted the FPR and boost just a tiny bit and left off on run 86. Run 86, as shown in the graph, is consistent with your statement above about AFRs. So your dyno isn't that far off on its AFRs, maybe a couple of tenths like DB says.

See guys, everyone is kinda right...

 

ShapeGSX, I can assure you that Al realizes the MAF sensor doesn't measure boost as do 90% of the guys reading this topic. He meant at around 26 psi with the stock turbo it puts the car into the last load cell of the map, basically maxing out the MAF sensor reading.

The exemption for the emission testing I believe in Ohio leaves you except permanently. I could be mistaken. I can't imagine them making you spend $600 each year to try and fix it.

Ted B. Spare tire is 37 pounds with the tools and jack and the front bumper beam is 13 pounds.

Smogrunner, that graph is much easier to read than the other. The other one that is posted if you look at it it sure looks like it touches 13:1. Now that I can read it on run 85 there is quite a bit of time spent at around 12.5:1 AFR's. On run #86 most of run is at 12:1. The AFR's move around quite a bit up top but it still isn't richer than 11.2 or so. Why it is moving around so much?

 

The afr's are very sensitive and when you dont have that portion of the graph sized properly the afr's can LOOK way off when in reality they are fine. The more you stretch the AFR graph vertically the greater the deviation will visually appear to be. Thats why its best to sometimes just post the actual .drf file.

No problem Dave, it's all good. I appreciate the comments and your opinion. I completely agree with you that there is a very defining point at which the stock ecu just isnt feasible anymore. Where you will be sacrificing a lot of power and driveability just by the mere act of retaining the stock ecu. In these cases of gt37+.......huge injectors.....and peaking maf readings......a standalone is the way to go.

Smoggy, haha....totally forgot about that next run. With all the commotion leading up to then it must have slipped my mind. See ya

Alfred at TTech

 

Accuracy in threads like these is paramount.

Again, that isn't maxing out the MAF sensor reading. That is maxing out the load axis of the map in the ECU. You can still tune, but you have to tune only using that last row that corresponds to ~26psi on the map. For drag racing (just about the only situation where boost would be this high. Don't come at me with a hundred places where this isn't true. I don't really care. ), this method of tuning often works out just fine. This isn't like maxing out a MAP sensor on a speed density system, which could be catastrophic.

If you ever max out the MAF, your airflow would get erratic, it would essentially flatline, but your airflow would continue to climb. As airflow increased, the ECU wouldn't add more fuel for the air above the MAF limit because it wouldn't be able to see that extra air, and the A:F ratio would get leaner and leaner.

The MAF sensor reading is already done by the time the ECU is looking up values in that table. The ECU uses the MAF sensor reading to calculate the amount of fuel it would take to reach stoich. While you see A:F ratios in each cell of the table, what you are really adjusting is the percentage of fuel that will be added to that stoich value. I assume that the software on the laptop does the conversion for you.

 

On the stock ECU for an 03-05, the Load Cells go to about 260% (approx 2.6bar absolute) You can increase that value as high as needed to get your sensor in range.. Combine that with a blowthrough MAF sensor, which can also be easily calibrated both in the control box, and in the ECU, and you can map as much boost as you can throw at it..

The stock MAF certainly can't flow enough air at some point.. but the ECU can certainly handle it, like Al said, recalibrating the sensor, and rescaling the load Axis, and thats just within the ECU..

Will we see cars making over 600whp on a stock ECU? Well, Time will tell.. Is it possible, I certainly think so, and is the ecu capable of it.. Most certainly.. Is it the best tool? For a street driven car, maybe...

My load Axis is scaled to 320%, plus my blowthrough MAF is calibrated to read close to stock, I'm not up to 26psi of boost yet, but I have not run out of the map where I have to tune the last load cell.

Plus there was another discussion about overrunning the map, and what the ECU does in some circumstances (pulls timing and acts strangely) I have been able to eliminate that. I'll let you guys know when I move up to Race gas and try much higher boost levels.

Oh and this is on a GT35r turbo, boost levels at the moment are about 18-19psi with a very safe tune (not aggressive whatsoever) I hit 2000hz at about 4200rpm which would place me above the 260% load cell...

There is a little misinformation in this thread, I just wanted to clarify that its possible to go above that point.. The more you stretch the axis, you do lose resolution, I decided to drop 3 low load columns that were very infrequently used to accomodate adding the 3 new columns I used.. (280, 300, 320) Plus I have the RPM axis set to 9500rpm again, I dropped a few of the lower RPM intervals where its not as critical.

 

well im pretty much sold. Going back to the stock ECU. Plus I live in Austin and I have to pass inspection hahaha.

 

I think part of the problem Jack is that a few tuners here have spent little time with the new ECUflash. I'm guessing that most OE ecu information is coming from dealing with the old static hex decimal experience. ECUflash seems to be leaps and bounds in the making over that old system. At the rate things are going, if the ecu has control of it, pretty soon ECUflash users will too.

 

Thanks David for clarification

Shapegsx - David is correct in saying that about 26 psi or so the MASS AIR FLOW through the stock mass air flow meter reaches 100% measurment and there is no additional resolution

The reason why the reading is exceeded does NOT have to do with boost it actually is grams of air passing the sensor

Different state of tune cars will actually fully saturate the maf sesnor at varying levels of boost becuase its all dependant on air flow. 26 psi is a good rule of thumb on so called "stage IV" cars which hit about 360 whp on race gas.

The way you measure the MAF resuolution is by logging the maf signal into the ecu - when it reaches its peak it CAN NOT record any additional air flow.

You can scale your softwear any way you want after that point and all you are doing is tuning on the very last row of the fuel and timing maps

When you are exceeding the maf sensor reading range a in the case of smog runner's car you get a very unstable fueling delivery as it is hard to tune the car on one row of numbers at the edge of a chart. If the car pulls a little harder you go lean and if it pulls a little less you go rich - its hard to get a smooth fuel map on a dyno but nearly impossible on the road with up hills and down hills.

Running a car way over the max reading of the maf sesnor is great for making dyno charts and claims about how nmuch power you can make but its not so great for actually having a stable, repeatable and safe smooth running car.

 

Sorry if I was not accurate enough for your standards - often the only time I get to post on here is late at night after working a 10 - 12 hour day so often my writing is very informal

Hopefully my clarified post above sorts of the confusion on what I meant

 

I concur with your points on the issue really being the stock mass air flow meter and not the tuning maps

However

Please remember in the stock ecu we are not tuning actual duty cycle or injector on time as with a aem

On the stock ecu its a "estimated a/f target table"

There is a whole bunch of mathematical calculations and corrections going on in the back ground which may work for you or against you

AEM is like a rifle it shoots where you point it - its blunt - its accurate its clear

The stock ecu is more like dealing with a woman who expects you to "understand" how she feels and do things to make her happy even is she wont tell you anything. There is more dancing around and testing more watching and mystery with the stock ecu as everything is not laid out before you with exacting detail.

I think either method will get the job done - each has its advantages


When you reach over 500 whp its my opinion that AEM is the best path although you certainly can get the job done on the stock ecu as well it just will be more dificcult

 

Be careful, because mass air flow mirrors hp, and VE mirrors torque. A stock turbo car that registers 26 psi in the midrange and tapers to 19 psi at peak hp will register greater mass air flow at the hp peak (19psi) than at the 26 psi torque peak in the midrange. So where the load map is concerned, it isn't the MAF that is at its limit, just the factory load table.

One fairly credible source indicated the EVO MAF to be limited to around 65 lb/min, which is enough to meter some 600+bhp worth of air mass (GT35R territory). If this is the case, the limiting issue with the factory ECU lies in the load tables as configured by the factory. The load tables can be reconfigured, and should ultimately be limited by the MAP sensor's capability.