Increasing the MAF size will result in inaccurate readings by the ECU, as you saw. By increasing the MAF scaling the load the ECU thinks it is seeing was raised also. The ECU will be adjusting fuel for load that is incorrect. We're finding out that its ok to make mild adjustments to the MAF tables to compensate for the extra air being forced into the engine that it isn't used to seeing. But how much a mild adjustment really is is what needs to be discovered. This will be the difference between slightly tricking the ECU and having the ECU running blind with changes too far out of tolerance.

 

^senate your running a 501 maf right? I believe thats the eclipse one, same as mines. By looking at your maf size you posted you haven't really increased the size much. Its 237 now right? Stock is 215? So did you use a formula to calculate the area difference between the two mafs or did you just adjust the maf size, then adjust the latencies and scalings to get the fuel trims in check? kinda a guess and test method per say?

 

4G, I think we'll find that that are multiple ways to the same end in this situation. Technically, MAF scaling and MAF size would lead to the same result as they work together. The MAF scaling table is based on the MAF size, so if you adjust the MAF size table it very similar to adjusting the entire MAF scaling table, though the load values might respond a little differently. Adjusting the MAF size will affect closed loop fueling as well.

What I've found with Lancers is that they will hold a low load value untile you really start dialing them in ... then load will increase. I've tuned NA lancers that wouldn't hit over 80% and pushed them to 95%+ with just fuel and timing.

So, what I think will happen in your case is that increasing the MAF size will bump the load up, but when you get your fuel where you want it and add a little more timing it might bump the load a little too far. I'm sure you can find a happy medium though between MAF size and scaling adjustment.

 

increasing the maf size would be a universal change affecting all hz ranges correct? this would essentially affect idle and cruising closed loop as well. and would be corrected by the ecu with low and middle fuel trims. doesn't the low or middle fuel trims affect wot?

 

Yes, it would shift the entire hz range and affect closed loop (idle/cruise). Yes, the ECU can correct up to 25% either way (+/-), but you want to keep the trims as close to 0 as possible. No, fuel trims don't affect open loop fueling. Log the O2 Feedback Trim value ... if it's at 0 and not hopping around you're in open loop (or decelerating with injectors cut).

What I'm saying is that the MAF size is correct ... you haven't changed the MAF itself. The MAF scaling should also be correct to around 500 hz ... basically everything in vacuum should be just like the factory and should not need to be modified.

Boost is causing the issues. The MAF is scaled for a NA vehicle and is based on the stock VE of the engine. When you start to pressurize the intake charge you throw this reading off as you're shoving in more air than the ECU realizes. So, the MAF scaling is adjusted to compensate but only in boost.

If you've changed injectors and your fuel trims are way off, adjusting the MAF size and scale can help get the fuel trims straight, but this is not technically the "correct" way to go about it. If the injectors aren't scaled properly, they need to be corrected ... not the MAF. This will lead to better drivability and a more consistent vehicle.

 

ok my low and middle trims are 3 and -6. i'll go back and set the hz range below 500 to stock.

 

Very well put! I couldn't agree more. These adjustments are in the early stages for Lancers. We're still putting together a workable harmony between these settings. The solution will come in time if everyone has the patience to see it through.

 

i'll have to recheck my fuel trims.

last i checked my low was +2 and mid was 0. Mid was -6 but I bumped up my injector scaling to 366 and it landed at 0 now.

this is with my MAF scaling x2 from stock values and my MAF size at 240 i believe...

 

whats everyones IDC during WOT at 10 PSI? Mine is around 70% already with 440cc injectors

evo guys say to add 30% IDC if you want to switch over to e85...

Im curious what everyone else is seeing, maybe my walbro needs to be changed or the filter

 

mine is about 70% idc at 8.5 to 9psi with 11 to 11.5afr at 5800-900rpm

 

thanks comp. i just checked mine with my current latest tune and at 10 PSI my IDC is at 75% - 80% at WOT
i guess 440cc isnt enough!

 

yeah my guess is 12psi would be the max on these injectors(on stock fuel pressure).

 

Now that it is really cold at night, I see a drop of about 50 degrees of IAT compared to day time IAT.

And my AFR goes lean a full point to 12.2 instead of 11.2

I did a couple of pulls and my logs show 0 knock... but is it safe?

 

12.5 would be the leanest you would want to go. any higher and you would want to watch egt. 12.5 is best power afr. i was running close to 13 afr for the longest until now but i havent had any problems. id rather stick to a safer afr under 12 for daily driving. whats your timing map look like?

 

im thinking about buying a new walbro, the high pressure GSS342. Is that what everyones is using?
im not sure which walbro i am using right now, as it came with the RRM kit...

Im too lazy to upload pics from my laptop, but my map goes like this:

RPM ---- Timing
3000 ---- 14
3500 ---- 12
4000 ---- 9
4500 ---- 7
5000 ---- 11
5500 ---- 17
6000 ---- 21
6500 ---- 22

still room for advanced timing? BTW this is on 91 octane