Mother

Custom Supercharger FVD Tuning..Project GULF

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Well I thought this is a good time to post on progress on the tuning of my car. FVD is doing the tuning thanks Willey and Mark, I installed the Duramatic software for the parameters and their Flash utility software for installing the modified ECU map. I am hoping to do the first tune at my residence and the final on a dyno, at present the car runs really rich and have plenty of error codes and hunting of the engine itself so getting it to idle is not possible at this time, but I will admit I was nervous running it to operating temp.

We are trying to get a way of seeing what the mixture is since I am not reading anything like proper FRA bank 1=99% and 2 =95% and RKAT 1=0% or 2=0% the camshaft positions 1 or 2 also registering 0%. I was expecting initial problems just not the parameters that I really need. I feel I am tuning in the dark but one thing we agree upon is the the injectors are almost twice the size of stock so it must be rich. FVD has shipped my parameters over to the German engineers and will know more what they say when they take a look next week after vacation, boy are they going to have fun when they get back.

I have done some educated guessing here on the hunting that with flowed 48# injectors that the error code #115 MAF "out of range" is showing the ECU is trying to compensate but can not. I am from old school tuning and not familiar with this stuff so feel welcome to input your ideas they are appreciated.

ERROR CODES:

115 MAF out of range
13 heating power ahead of cat bank 1
62 damaging to cat
63 cyl 1 misfire damamging to cat
65 cyl 3 damaging to cat
67 cyl 5 misfire damaging to cat.

I have some videos please excuse the quality, also a data file of many parameters of engine running log file (xls format) for the hardcore anyone want to try to graph it?. I will add as tune progresses.


Located at:

http://www.webbspot.com/Porsche/fvdvideo.html

Tippy

MAF out of range - on American cars, which I assume is the same as the 996, if you mixed bigger injectors without calibrating the MAF, the car would have big problems idling

misfire codes- obviously from being so rich causing plug fouling

I am surprised the engine runs with 2 X's the injector size.

Have you ever thought of contacting Evolution Motorsports and see if you could get their software and hardware for a baseline tune? After, you could do a custom tune.

GIAC supplies Evo software.

Keep us posted on the progress!

Mother

I agree on you on the MAF it is a new MAF and would think it would not need any calibration as long as the A/F mix was in tolerance? How would you if so. Regarding the misconception of Garrett and EVO the reason I choose FvD was because Garrett will not supply a base map and was told to talk with EVO then they gave me the run around to talk with Garrett, so I will not do business with either because of the "M" word..

TheSpeedDemon

+1 (highlighted area). On my S/C 351W '89 Mustang I moved-up from stock 19's to 48's and had to get a new MAS that was larger for more air-flow and supported the injectors. It is a PRO-FLOW unit and if I change the injector size I have to get it adjusted again.

I have heard of adjustable ones but you need special software etc. to do the changes, something you find at dyno places.

Tippy

My 2 cents:

From my limited understanding of EFI, the A/F will be off because your pulse width and duration are the same given by the computer, but now you have injectors that flow more fuel. It is probably going haywire trying to compensate and lean.

Your best bet would be to post this question in the 930 (911 turbo) forum, there are some guys who really know EFI quite well.

The only issue is, they probably wont know about the camshaft timing data.

I got the same run around as you did. I became slightly discouraged now with turboing my 996, I feel these tuners are being secretive.

Tippy

The Pro-Flow gave a friend of mine big time headaches, his car never idled because the PF's trick the computer istead of being calibrated. I guess you had good luck.

Ubermensch

If you're doing any of this without a wide band oxygen sensor you're looking for trouble. Step #1 in this is to get your AFR's in a reasonable range.

1999Porsche911

In the stock engine, your map tables correspond (among other things) to the input from your MAF. Now that you have increased the amount of air passing by the MAF, your computer is opening up the injectors to come up to proper balance. However, off boost, all the air reported by the MAF IS NOT going into the engine. Therefore, you run rich and your O2 sensors try to pull back the fuel, etc, etc. At WOT, without limiting the current to the MAF, you will exceed the mechanical limits of the MAF and it will eventually burnout. Having no idea what turning has been done on the mapping, you first need to get the MAF's reading down to a level around 4.5 g/s at idle. This should get your fuel/air mixture within a managable level. Probably the best way to do this is to install a resister inline on the cable to the MAF. In effect, you are telling the computer that you have less air entering the engine. Even with the stock mappings, the engine should idle smoothly as the O2 sensors will properly manage the fuel.

Now, during off vacuum operation, because you reduced the current to the MAF, the engine is getting more air than the MAF is reporting to the computer and you are running lean. This is where the fuel maps come into play and must be adjusted to higher levels based what the lower MAF signal is sending the computer.

Remapping should be quite easy for the tuner if he knows the actual air flow to the intake, both on and off boost.

Tippy

'99 - You say the motor is not receiving all of the metered air. Doesnt the BOV recirculate the metered air?

Your S/C kit came with a bigger MAF sensor? Why I ask, is I have a friend putting 550HP to wheels using the stock '87 C3.2 MAF. I wouldnt think that the 996 meter is maxed with the S/C.

And you say tricking the MAF, I have seen this cause mad problems on a friends car. The car made excellent power at WOT but never idled properly.

1999Porsche911

No one said anything about a bigger MAF.

On vacuum, not all the air metered by the MAF is entering the intake.

The fuel metering is dependent on the signal it receives from various sensors, including the MAF. All the remapping is doing is changing the amount of fuel injected based on lower input from the MAF.

Since you cannot increase the maximum amount of current to the MAF without burning it out, the signal to the computer will remain the same (by way of resister control). What the programmer does is simply calculate what the actual air flow rate is with the SC and adjusts the mappong. If the SC doubles the actual amount of air into the engine, then the mapping would be adjusted to double the amount of fuel based on the same signal.

Example.

Stock engine MAF signal of 50 g/s injects 1 pound of fuel

SC engine MAF signal of 50 g/s injects 2 pounds of fuel

Tippy

Sure, the mapping I understand completely, it is the MAF metering I am not following.

If I recall, the air is recirculated back through the inlet of the S/C from the BOV. This causes less air to enter the MAF and balances out the metered air. This principle works on Fords and I assume on the 996 since the MAF is before the S/C?. On a side note, LS-X motors air is metered after the S/C, the boost can be dumped to atmosphere.

By tricking the MAF, I would think all is fine and dandy until you start reaching boost. Then the resistor would limit "actual" airflow sent to the computer by the MAF signal causing a lean condition, the engine is actually injesting more air than it is reading. I may be missing something though.

1999Porsche911

Yes the off boost air is circulated outside the intake but the MAF is still drawing more air than is getting to the intake, so you need to calibrate the MAF signal.

The resister DOES NOT restrict airflow, only the current reported to the computer. As I mentioned in the previous post, you MUST limit the maximum signal from the MAF or risk burning it out. This is the ONLY purpose of the inline resister. It is the programming of the computer that determines what to do with the "incorrect " MAF signal. The stock program would make the engine run lean, but the modified program would be adjusted so that it injects the proper amount of fuel.

When the computer is programed at the factory, it has already been determined what the airflow ACTUALLY is at various rpm's and other conditions. From that starting point, the computer is programmed to inject a specific amount of fuel based on that airflow. The linear MAF signal is just the vehicle that the computer uses to measure airflow and temp, but in no way controls airflow. The progammer knows that the MAF reading will be "X" when the ACTUAL airflow is "Y" and tells the computer to injected "XY" amount of fuel.

The bottom line is, the computer is in control and is simply receiving signals from the sensors. The computer programming is what determines what to do with these signals.

Tippy

I worded it wrong, I know the resistor doesnt limit airflow of the MAF, it limits or tricks the signal.

Mother

I agree I feel I am walking on ice, I was depending on the FRA and RKAT for some readings on A/F but No-Go. I am thinking of a autometer.

Mother

1999, Tippy,

If at idle the engine is not processing any more air flow then stock, so why would any changes be needed to the MAF. Would it not just run rich and still get the MAF error #115 "code out of limits".