What are your AFRs and IDCs like under boost/load after you "trick" the fuel/spark cut?

On old cars the fuel cut was crude and would sometimes still let a little bit of fuel in causing an extreme lean condition = boom

Ask me how I know

 

That is an interesting idea, and I don't see why it wouldn't work. But it would be making the ECU's decisions more.. convoluted. I'd be curious to see what they say.

And as far as boost threshold on a GT2554R v. 10-12psi pulley on a C15 Rotrex.. You should only be seeing full boost on the Rotrex at redline, where as the GT25 should be spooled to what ever max boost is set to by 3-4000rpm. You should start making boost sooner, but where you make full boost should be considerably later in the rev range.

The Rotrex units have a very linear power delivery because of this. The few things that would change in the tune would be when and where you get above atmospheric pressure and then how much air the compressors are actually moving.

But out of boost and in vacuum the tunes would be the same basically.

You wouldn't necessarily need to adjust your tune when you add the methanol either.. you have oxygen (lambda) sensors to help there.

A progressive controller, 1gal or larger reservoir, a ~200cc/min or larger nozzle and a 150psi pump should have you all set, and you can tune the controller seperate from your Hondata ECU.

 

Haha I rely on my wideband so much I call it my explodometer. As long as it stays below 13 I feel secure street tunning. But afrs are exactly where I want them when the fuel cut would happen. I've got it now where I can wot through 3rd gear between 11.5 and 13. I'm retarding 1 degree per psi for safety. The stock ecu is more adaptive than I ever expected. All I had to do was offset the stock o2 by 50% and the ecu always adjusts my fuel trims to stay right on 12.5 in closed loop.

I believe the root problem is that the ecu is also using the tps in conjunction with the maf and map to determine what the maximum load should be. I don't have a dynamic enough control over the tps signal.

 

Anyway, to tune this out completely, I'm slowly clamping the maf lower and lower between 3500 and 6000 rpms. It seems to like this. However I have to add more fuel on the back end in the maf fuel map on top of the map fuel map. It takes a bit of trial and error to dial in the afr every time I clamp it lower because the maf voltage curve is non linear.

As others have said, using the fic, especially with a maf, is like walking a tightrope.

 

Also, regapping my spark plugs because on one run the ecu detected a misfire in every cylinder. Inspection of my plugs reveals no sign of detonation so it must be blow out. I had them just under the stock gap, had them at .05 changing to .04

I have to say despite how annoying it is, I am very glad the stock ecu is so protective of the engine. The misfire put me into what I will call 'super limp home mode' it takes over the tps and wil not let you go over 25% throttle until you restart the engine. I assume it will do the same in a detonation event.

 

DSM, I started reading the mega quirt info. I have my weekend covered. Theres so much info but they dont talk about MBT just retard timing 2 degrees for regular. That leads me to believe the ecu in the Fit is very complicated and also has a VE generator built in.

 

Haha I like that.

If you can I would err on the side of too rich.. 13's on pump gas in a 10:1 boosted motor is asking for pain and aggravation. I'm sure you know this though.

11.8:1 is the leanest I go under WOT on pump gas alone. Then I try and balance between boost and timing.

Pump gas likes boost much more than timing. Below your boost threshold aim for as much timing as possible to keep torque up, and thus acceleration. Then when you start to spool bring timing down and aim for high boost. 14-15psi and low timing even as little as 10-13* advance or less can produce alot more torque and power then 5-6psi and 15-20*

Ideally if you can find a balance between AFR, advance and boost say 14-15psi and 17*+ on a slightly richer tune you will be getting the most out of that little hairdryer



This is something you may have to play with alot, I run .028 for anything under 20psi. And as small as .018-.022 on a 7 range plug or colder for beyond 30psi.

Stock ECUs are incredibly capable. Like I said earlier, often more powerful than many sophisticated standalones! It is nice to have the ECU watching your back though! I haven't had that luxury on many cars. DBW and limp mode is kind of nice in that respect. If you have to you may want to consider stepping up to an MSD or ARC 2 ignition if this problem persists. I know at least the GD coils are not very robust. I am trying to find some data on just how much they kick out.

The GE has so many interesting quirks, I wonder what made Honda switch from Speed Density, which they use on many cars, back to MAF sensors?

Do you get a raw MAF Hz reading in the FIC? It sounds like you are making a lot of progress.

Keep us posted! Excellent Job!

 

The GDs are Speed Density and rely on a set VE table. The MAFs just use MAF output to gauge air mass entering and spray fuel accordingly, and don't really need a VE table. They do however make a similar calculation based on the concept of Load.

Which is Air mass in grams divided by revolutions per minute divided by the number of cylinders.

I keep trying to find some group who will give us the time of day and provide a real tuning option. I like the FIC, I think there is a lot of potential, but I want a full standalone system. I have big plans for my GD.

It is going to take time though between everything else going on.

I am dedicated to a 300whp/300lb-ft DD Fit on either Meth/Toluene or a switch to E85 and two fuel rails.

I have most of what I need to do it except time and money got tight recently. But this will be happening.

Let me know what you think of those links I sent you for the weekend! Should keep you busy

 

The hotwire style mafs use a standard 0-5 voltage scale rather than a frequency scale I'm pretty sure anyway. Otherwise I would have the wrong fic unit since this one does not support frequency based signals.


1st gear and 2nd gear like to oscillate a bit but 3rd and 4th stay on 12.1 and stay there. At this low boost level I can get away with alot. Spool up is nothing short of instantaneous on this tiny turbo.


Anyway, technical question. The ecu is only giving me about 15 degrees advance base timing under wot and I'm taking 8 degrees off of that under boost. Am I going to gain a significant amount of power when I only take off .5 degrees per psi.

 

So 7* peak?

You may be able to get away with plenty of boost without taking away more timing, but you are running 12:1AFRs on a 10:1CR so its tough to say without being there and seeing what sensor feedback your getting. Do you see any knock retard?

I would bring timing up to 10* peak leave boost the same and try and bring you AFRs down a few points.. maybe 11.5:1 or 11.8:1.

 

I'm just loving this stuff.

 

Here some info about Dynamic Advance & Dynamic Advance Multiplier Explained. CobbTuning.com - Dynamic Advance & Dynamic Advance Multiplier Explained

 

I think Maybe I have figured out the problem. The hotwire style maf is based on the cooling effect of air passing over the hotwire. Because I am using a blow through maf setup, the air passing over the hotwire is over 120 degrees. I believe the output voltage is somehow compared to the iat voltage to generate an estimated gram air flow. To test this theory I am going to try to clamp the iat voltage with my last remaing sensor channel on the fic.

 

I have my fingers crossed for you... Hope it works, your theory sounds viable to me.

 

Wow 120F IAT's at this time of year? Someone needs a real intercooler How much boost are you running on your T2Small? It could be chucking out air above 325*F or higher Depending on where you are on the compressor and turbine maps...

And you are correct, that is exactly how the calculation is done, the MAP/Baro sensor is directly involved as well.

Once the Maf voltage/Hz are translated to a working value this is all entered into the equation pv=nrt to derive your airflow/rev/cyl, so I would check out your MAP/Baro voltage as well!

Have you inspected your MAF to make sure it is not contaminated or dirty in any fashion?

 

Those are the primary tables I am discussing, particulary the second table, in those economy/performance discussions where fuel grade comes up!

There is a decent description there as well. I really just need to come kidnap you for a weekend when the weather gets nice and make you co-pilot while I do shake-down pulls

It will all come together when you see it in real time on the laptop. It's addicting!

 

Aye, just a few squirts of maf cleaner on it. This does make sense since my maf clamp is built around stock runs at 30-40 degree Iats. In boost, I'm really just simulating a stock maf wot run so the ecu puts out consistent fuel that I can tune around. It's really not THAT hot since even idle is about 70 degrees.

 

What was surprising to me was that the largest amount of advance on the Subaru the tables were from was only 42 degrees... I see as high as 47 on my Fit as it is tuned right now, but as I have said before, it runs very rich... I suppose the Hondata reflash found this tuning to be the best way to safely make horsepower.

 

Ya Im just teasin, 70 is still kind of high for idle right now.

The GE ECU continues to impress, I just wish we could hack it, as it would be a very powerful tuning tool. Much like Evo ECUs and K series Hondata ECUs

I wish we could get groups like Race Craft Academy (Singapore?) to spill the beans on how they reflash GE ECUs.

What max MAF voltage did you see NA @ 30F? What IDCs?

How much adjustment does the FIC give you as far as injector compensation?

 

What is the ambient temperature up there? I was seeing 120 temps the last time I drove to town but it was like 77 degrees outside that day.