[Guest]

2 points of view, please help to settle this one:

me: SAFC (fuel computer) is the box which along with the increased fuel rate/airflow signal, fools the ECU into thinking it doesnt need to fuel cut, then you use the S-AVCR to increase the boost, the boost controller has no ecu input at all.

barry: S-AVCR (boost controller), is what fools the ECU,it interupts the signal from the airflow meter to the ecu,and fools the ecu into thinking it is boosting at normal levels when it is'nt.Your Blitz does exactly the same thing.The AFC has no function connected with removing boost cuts.The AFC is purely there to enable you to optimize fuelling.

please stop these two friends argueing.....
lee

 

[Guest]

I don't know if this helps but I have copied it from a Japanese site.

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But seriously it says the folowing. Not sure which side it helps!

The A'PEXi Super AVC-R is the ultimate boost controller. It is the only boost controller on the market boasting an integrated injector pulse monitor. It is the only boost controller on the market engineered to increase boost response (up to 1500 RPM in some vehicles).
The A'PEXi Super AVC-R is the only boost controller with an RPM-specific self-learn mode which allows the boost controller to memorize the boost characteristics of a particular vehicle and adjust the boost pressure accordingly. This allows the unit to control boost unlike any other unit on the market. Vacuum and boost pressure are shown on the unit's easy-to-see display. A series of colored LED's also serve as a bar graph and monitor for the unit's various functions.
The booster controller is a boost duty setting that allows the user to control the amount of boost overshoot. The Super AVC-R is the only boost controller that combines the self-learning mode with an RPM specific overshoot protection feature for unparalleled boost stability. There are no dangerous calibration modes associated with Fuzzy Logic systems.To control boost, the Super AVC-R uses a high-quality solenoid valve as opposed to a stepping motor. This is the same technology that was used on the turbocharged Honda F-a race cars.
These solenoid valves are proven to control boost more accurately and are much sturdier in design and construction than a stepping motor. The Super AVC-R reads information from an injector pulse signal wire from the vehicle's ECU and a self-contained pressure sensor. The signals are then interpreted by the AVC-R and used to control the solenoid valve.

The second generation Super AFC follows the highly successful Super AFC in an upgraded package. The Super AFC is a vehicle specific fuel computer that modifies the air flow meter signal/pressure sensor signal and allows the user to either richen or lean the fuel mixture. Adjustment ranges from |PLS|/-50%. The Super AFC boasts an 8 point adjustable fuel curve with 500 RPM increment setting points. The Super AFC also allows the user to adjust fuel enrichment according to either LO/HI throttle positions. The AFC also cures the erratic idle problems associated with open atmospheric blow off valves on hit wire air flow meter equipped vehicles. Monitor Mode shows analog meter faces, Y Graph Display, Numerical Display, Peak Hold, Replay Mode, 1 point/10 point and ghost map tracing. All correction factors are also displayed in percentages. All values and graphs are displayed through the exclusive VFD (Vacuum Florescent Display) screen.

 

[Guest]

that is what they do, but we are discussing the way RC use the 2 of them to avoid the fuel cut.....
opinions please.

lee

 

[Guest]

That is not really a matter of opinion, Lee.

The AVC-R controls the boost. At an approxiamate Karman Vortech value of 1700 Hz (and depending on intake temp and barometric pressure) the ECU will cut the fuel off. If you raise the boost with the AVC-R you will reach that fuel cut level at around 1.2 - 1.3 bars, sometimes less. It is therefore not the AVC-R controlling the fuel cut limit.

The S-AFC can be used to lower the Karman value and therefore fuel cut will not happen is that value is kept below the figure I gave. However, if you lower that value, you lower the amount of air the ECU considers to have come in. The ECU will then use less fuel to compensate for less air. That is why you have to use a fuel pump and pressure regulator to increase the fuel pressure: to force more fuel in.

You then need to measure the air fuel ratio and set it so you dont run lean or to rich using the S-AFC. That would be between 11:1 and 12:1.

 

[Guest]

Lee,I explained it wrong,the AFC works in conjunction with the AVC-R ,the AFC tricks the ECU,sorry for the confusion,I got my Apexis mixed up.

Thank you Claudious you explained it well.The Power FC with standard Evo 6 map has a kharman value of 2500hertz before fuel cut,which means you have good safety margin when running higher boost.

Lee,look at your power graph,I cant Im going from memory.Look at the first point the power starts to plateau,before the spikes,that will tell you the usable bhp on the road.If your 350 bhp is a spike within say 500 rpm,that that is not usable power.If you then consider improving fuelling,you should get more usable bhp,just a thought,just trying to help

I must say the Gems seems good value for money from Steve Hill,and under different circumstances I could be tempted.But I do like the Apexi technology, it is a good match for the EVO,and I have commited to a tuner who I trust so I will follow their advice.

I still have a lot to learn,but thats part of the fun.

Best Wishes Barry

 

[Guest]

if i got the motec fitted, do i still need the avcr/safc?

 

[Guest]

nope. motec should take care of everything they do and more.

 

[Guest]

how much boost does the Motec hold in 4th or 5th at 6000 rpms?

 

[Guest]

I thought that even with both you needed to increase the fuel pressure to prevent cut.

Jeremy

 

[Guest]

Jeremy,
You don't need to do anything to the fuel pressure to remove the fuel cut.
The fuel cut is based purely on the airflow reading and so you either alter the specific Karmann value within the ECU that the cut happens at (sports ECU or fully mappable ECU) or you alter the signal from the airflow meter to the ECU (Apex'i AFC) so that the ECU sees a lower airflow than what is really going on.

Andy

 

[Guest]

Thanks Andy

So with my S-AFC and amp; AVC-R HKS induction kit a de-catted exhaust will be fine with no cuts.

I'll get it booked in for the day I pick it up

Jeremy

 

[Guest]

You have to up the fuel pressure with an adjustable regulator and then lower the apparent MAF (Karmann Vortex Frequency) reading to the ecu with the S'AFC to avoid the fuel cut.

If you lower the MAF count with the S'AFC alone you will run lean and bang goes the engine.

Other method is swapping to larger injectors and using the S'AFC to compensate.

For example (All figures are purely for this example).

Standard - fuel cut at 1.3 bar boost , MAF count 2000Hz, 560cc/min injectors @ 80% duty, 43.5 psi base fuel pressure.

Up the fuel pressure and tune with SAFC, MAF count still 2000Hz but ecu only recieves signal for 1875Hz, allows another 125 Hz count before fuel cut. Injectors now at 75% duty, 50psi base.

Change the injectors to 680cc/min and tune with SAFC, MAF count still 2000Hz but ecu only recieves signal for 1650 Hz, allows another 350 Hz count before fuel cut. Injectors now at 66% duty, 43.5psi base.

When the ecu hits the maximum count from the MAF it will trigger fuel cut, no matter what the set-up.
The trick to the SAFC is modifying the base fuel pressure or injector sizes to reduce the apparent MAF count seen by the ecu. On it's own the SAFC will do next to nothing - you must increase the fuel flow too.

 

[Guest]

Lightspeed - what is standard boost? E6 GSR

If I only want to tweak the boost say .1 of a bar (i'll use the Apexi kit to hold the boost and to build a couple of economy settings) will i still need to change the fuel pressure/or amount of fuel to prevent the cuts everyone seems to get after fitting induction and amp; exhaust?

Thanks in advance

Jeremy

 

[Guest]

Jeremy,
The standard boost on an Evo 6 is 1.1 peak and holding 0.9.

Fuel cuts tend to happen at around 1.2-1.3 bar but it depends on the air temperature as it is based on the airflow calculation and not on the boost level as explained above.

As a result, if you were to use the Apex'i to not go above 1.2 bar but use it mainly to allow you to run with say 0.7-0.8 bar for economy (which is roughly the figure you get when not bleeding off any air from the line to the actuator) then IMHO this would be OK to do.

Andy

 

[Guest]

Jeremy

Don't book your car in straight away. Drive it for a few days because then, when you have the goodies bolted on, you will really feel the difference. Otherwise, you will never know how much better it feels

Strange thing is, doesn't matter how much power you have, you get used to it. The car seems to be getting slower

 

[Guest]

Simon

I know what you are saying but I think the exhaust is a must and as I've already got the Apexi bits I thought I would have it done at the same time. I know its no comparison (flame suit on for scooby owners) but since my Scoob has been de modified it is a real pig to drive with only 221 bhp (it had about 300 at the peak, cold weather etc.) I do miss the exhaust note and amp; volume (un-equal length manifolds are good for 1 thing at least). Also I cant go chasing Evo's at the moment. LOL

It is also really convenient to have it done on the way back from picking it up (i've got the day off).

If I want to run 1.25bar max say holding 1.2 will i need to change anything in the fuel pressure system?(I suppose on a really cold day it could spike to over 1.3?)

Thanks again all

Jeremy

 

[Guest]

Jeremy,
This might not be the best answer in the world but how about this:

Try it at 1.25 and 1.2 and see if it cuts. May well not cut now the weather is getting warmer but may well start to cut next winter.

If it cuts then you've got 3 options:
1. Turn the boost down until it doesn't cut
2. Up the fuel pressure with an adjustable regulator and new pump to stop the cut and then retune the AFC.
3. Go for a Ralliart sports ECU that ups the fuel cut and fuelling and allows you to run up to 1.3 bar or go for a mappable ECU.

Andy

 

[Guest]

You should be fine for 1.2 bars approx.

It seems you didnt read my first reply, you need to up the fuel pressure and lower the SAFC value to run 1.5 bars or whatever boost you want.

No fuel pump required for 1.2 bars.

 

[Guest]

Claudius

Thanks for the reply's now i know from both of you.

Would anyone like to say what a safe level of boost is with standard internals.

Thanks

Jeremy

 

[Guest]

People have run 1.5 bar on standard internals without any problems so far. Ralliart recommend any more than 1.3 and you go for uprated internals (I think).
I don't want to give a definitive figure because I don't want to be responsible for someone popping their engine and then turning round and saying 'well you said it was OK'

Andy