RomRaider

Can't find much peeps with FMIC. This should be a popular upgrade.
Anyone with FMIC care to share some tuning info.
or better yet a map..

Well i maybe going to FMIC soon and will help you then if we have something simular, What setup do you have/looking for?

I am immediately drawn to posts like this since I have been scanning the forums and searching for others with the issue that I have been experiencing (and others have been experiencing). We're still working on it.

Long story short: Adding a FMIC increases the total volume post-turbo by 5 to 6 times. There is a lag between the air measured by the MAF and when that air hits the motor. You can expect rich spikes on spoolup. FIBET (enrichment boost error) has no affect. If the MAF curve is on the money then fudging the primary fuel is not the proper way to fix it. Fudging the MAF curve creates lean spots that will cause issues at part throttle. This is only a problem that you will notice when tuning your car with a wideband. People are coming out of the woodwork now and posting about how they have this 'issue'. One of the main questions is why hasn't this been discussed previously. Well, it has, just in the 'tune for money' circles. It seems that some get around this issue by keeping the stock MAF calibration on cars with Big MAFs. By doing this, the change in load at spoolup is nowhere near what it should be (you get more air). Thus, you have more fudging flexibility ... however, it is a fudge - pure and simple.

My TMIC tune, completed by me, was definitely more responsive on initial boost onset. It was also more responsive between gears. However, the FMIC is awesome once you area already into the throttle.

http://www.iwsti.com/forums/showthread.php?t=71375

t

I am going to throw the bs flag up on this right now. Lets talk about the physics of this for a second. Assuming we are talking about an STI here with a 2.5l motor. You know that the motor consumes 2.5 litres of air per complete 4 stroke revolution. Lets also assume that you are at 3500 rpm's @ 0 psi of pressure. At that rpm you can caculate how much air the motor consumes by taking the rpm/4 then multiply that by 2.5. That is 2187 litres of air per minute or 36 litres of air per second. If we are talking about 5 feet of 2.5 in diameter intercooler piping you can calculate the volume by pi*r^2*length which is 19.3 litres of air for a 5 foot pipe at 2.5" diameter. So it takes about .5 second to move 19.3 litres of air in a 5 foot pipe. Remember that this is at 0 psi as your turbo starts to spool and your rpms go up you are moving the air exponentially faster. The extra 5' of pipe you added takes tenths to miliseconds to "fill" (your not really filling because the pipe already has air in it) and pass air through. I dont think the extra 5 ' of pipe has any affect on spool up fueling especially as I have a front mount myself and expierenced this first hand.

there IS spool up lag with FMIC. I moved up from Perrin TMIC to TurboXS FMIC. Hitting full boost of 20psi (18g turbo w/ wrx) is only 300-400rpm difference for 3rd or 4th gear. However, much bigger difference is noticable especially 1st gear and little better than that at 2nd gear.

back to main topic... I just tuned the same way I tuned w/ TMIC. Factor in little lag at mid range (slightly richen 3500rpm) and improved top end (more timing and leaner fuel maps)

I disagree with you. First and foremost, the volume is greater than what you quoted. Second, even 0.1s is enough time to allow this to happen.

Again, more and more people are coming out now and discussing this issue. This *is* an issue. You just have to be an anal tuner with a wideband to notice it. It is easily masked by an improper MAF cal. My MAF cal is on the money. Spoolup from 2000rpms generates AFRs in the 9's around 3000rpms. The AFR then settles back down to 11:1 once I hit 3500rpms. Now, let's do this again but starting spool at 3000rpms. AFRs hit the 9's at 3500rpms and then settle back to 11:1. Do this again and start WOT at 4000rpms. AFRs hit the 9's and then settle back down to 11:1. Do you see where I am going with this? My MAF curve is on the money between 4v and 4.5v. However, I can produce an AFR in the 9's at 3.8v, 4v, 4.3v. It doesn't matter.

FUTHERMORE, I have even gone to the extent of testing STEADY STATE MAF conditions (like holding 3.8v on the MAF). Guess what? My MAF cal is on the money. That is the key here. Go and hold steady state on your MAF for a particular MAF V. Check the AFRs on the wideband and match them to the fuel curve. Easy as that. Mine are there.

I've also fully pressure checked my system. It is good to go.

Good explanation:
http://www.iwsti.com/forums/showpost.ph ... stcount=87

t

You could try calculating the pipe length and I.D. to come up with the total volume(plus the core size).You might be suprised.Great article on I.C.'s http://www.are.com.au/techtalk/intecoolersMR.htm

hey wolfplayer, isn't your dip in AFR caused by tip-in throttle map?? Maybe injectors are dumping too much fuel with big delta throttle position?? whenever I floor, mine goes up little bit (from 14.7:1 to 15~15.5:1) and goes to target AFR.

I agree with 18gwrx, the throttle delta enrichment sounds like it is the issue. When I log, if I have a huge throttle change I notice my AFR's drop down below my targets, but I also notice that the ECU decides to add up to 25% more fuel (LTFT) during that throttle change. When the ecu stops adding fuel I hit my targets also. That tells me that it has nothing to do with how the MAF is reading the air, or the "lag" until it gets to the cylinder, but more to do with what the ECU decides to do during the throttle change. If your MAF calibration is dead on like you claim then it sounds like you need to take a look at the Tip In enrichment.

You guys should just read the main post instead of inserting various comments here. I tried this already. As a tuner - of COURSE it was one of the first things I tried - lol.

In no way is this a throttle tip-in issue. Throttle Tip-in is immediate. Throttle tip-in happens right away. Again, read the main post. Been there done that. And - it makes sense if you think about it. If you floor it at 2000rpms then throttle tip-in happens. We're talking about going rich at 3000rpms. There is a large time difference between 2000rpms to 3000rpms. Throttle tip-in has long ended at that point. This is not throttle tip-in. Don't worry. I even tried some crazy throttle tip-in maps to put this to the test. It's not THROTTLE tip in. However, this could be fudged/fixed with access to an "enrichment vs. delta load (or MAF V)"

t

I am out of closed loop almost instantly when I hit the throttle. At 2.5V the car is in open loop. My LTFTs are 0.39 in open loop. I've tried delaying the transition to open loop (along with crystal_imprezav trying it too). It makes things worse. The rich fuel spike is independent of open and closed loop. It will happen no matter what state the ECU is in. It happens when there are large changes in MAF V (or load). Simple as that.

If your ecu calibration is adding +25% LONG TERM fuel trims then YOU definitely have an issue with your MAF calibration. You should never see anything more than -5% to +5%. If you do, you should recal your MAF curve.

Again, read the main post since this is all covered in there.

t

Mine goes up too. In fact, if anything, I need MORE throttle tip-in. I'm running a fairly LEAN tip in right now. I have also rescaled it in order to get a better handle on the lower tip-in values.

t

The MAF curve is fine, it only happens, like you stated when there is a large load ramp up. If I roll into the throttle vs. stabbing it I dont see the additional fuel add, the fuel trims hover around 0% and I hit the targets just fine. There has to be an additional map that the "professional" software has access to that we havent found yet.

Edit: I dont recall if it was the STFT or the LTFT where the fuel was added, I dont have access to my logs this second.

i see what could be causing what WP reports.

basically, with a FMIC in place of a TMIC, the turbo is spooling up and PRESSURIZING a much larger volume of trapped air between the compressor and the intake valves.

during the time it takes to pressurize this airspace, the mafs picks up air being drawn into the compressor, compressed, and "stored" in the chamber between turbo and intake valves. during this time the car is running rich, because the air is passing the mafs but not getting into the chambers. if it WAS, then there would be no buildup of manifold pressure.

without REALLY digging whole hog into the code itself (not just the tables) of the ecu, the only way i can see to eliminate this properly is to just move the mafs closer to the tb and be done with it already.

I disagree, I can watch the ECU add fuel via the fuel trims when you have a large load ramp up. The ECU doesnt know you added a buch of piping after the MAF. So why is it adding so much more fuel? IMHO it has nothing to do with how much more IC piping you have, but more to do with how the ecu is responding to the quick ramp up of load.

Edit: Just for clarification if it was MAF related I woudnt see the fuel trims spike when I stab the throttle, they would hover around 0 and the car would still go uber rich.