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Old 11-08-2018, 10:42 PM   #1
OOGA
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Default FMIC questions

I'm looking at getting a Mishimoto FMIC, right now I have process west verticooler, blouch 1.5xtr (eventually it'll be bigger) Cobb intake, Perrin Turbo inlet. I'm tunes with the verticooler. My question is could I safely drive with a FMIC without getting a new tune. I know I wouldn't benefit from it, but would it drive okay? I will get a tune when I go for a bigger turbo soon, but for now it's hard to justify the cost.
Also any opinions on mishimoto intercoolers? I have their radiator and it works flawlessly.
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Old 11-09-2018, 12:08 AM   #2
mikeydrives1
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Nope, I would advise against going to a FMIC without a retune soon after. There is a bit of re calibrating required for use of more piping, especially in a MAF based scheme. You may want to consider switching to speed density as well when you go front mount, your tuner will thank you.
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Old 11-09-2018, 12:34 AM   #3
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Originally Posted by mikeydrives1 View Post
Nope, I would advise against going to a FMIC without a retune soon after. There is a bit of re calibrating required for use of more piping, especially in a MAF based scheme. You may want to consider switching to speed density as well when you go front mount, your tuner will thank you.


I've considered speed density, but heard there's no drivability issues at low speeds. I know there's a hybrid system but I don't know anything hint about it. How does temp effect SD tunes?
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Old 11-09-2018, 12:34 AM   #4
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Also would an etune be worth looking into for such a slight change
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Old 11-09-2018, 12:52 AM   #5
mikeydrives1
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There are reputable E-tuners out there who do fantastic work. Speed density has compensations that adapt to temp changes better than a MAF based scheme does. Generally from my experience, low speed drive-ability issues were caused by MAF related tuning to begin with, since its a sensor that relies solely on air flow to determine fueling, sometimes its placement, shape, size and intake design picks up eddyswirls and uneven flow of air, thus causing slight hiccups in fueling. Speed density solved this because its relying on whats going on much farther down the line. This is especially true for front mounts where your dealing with a large amount of space between where the MAF is and where the combustion chamber is.
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Old 11-09-2018, 01:19 AM   #6
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Originally Posted by mikeydrives1 View Post
There are reputable E-tuners out there who do fantastic work. Speed density has compensations that adapt to temp changes better than a MAF based scheme does. Generally from my experience, low speed drive-ability issues were caused by MAF related tuning to begin with, since its a sensor that relies solely on air flow to determine fueling, sometimes its placement, shape, size and intake design picks up eddyswirls and uneven flow of air, thus causing slight hiccups in fueling. Speed density solved this because its relying on whats going on much farther down the line. This is especially true for front mounts where your dealing with a large amount of space between where the MAF is and where the combustion chamber is.


That sounds good, I'm not sure if they could etune to speed density from maf tune. But I'll reach out to some and ask some questions. Might get an MAF etune till I go see my tuner to go speed density. If you know of any good etuners let me know. Thanks for all the Info.
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Old 11-09-2018, 02:40 PM   #7
mrsaturn7085
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I'll clear a few things up here:

A MAF tune will handle this change without serious issues. You might need some slight tuning, but if your IAT values were stable before, they aren't going to be any less stable now. The density you gain from any additional charge temp. cooling will likely be handled by closed loop control because it will be minimal unless you had serious issues with the old IC and tuned around them. Under load, you should take a few wideband logs and tweak the fuel table a bit. Your acceleration enrichment may require more attention given the change to the system volume pre-throttle (or it might be fine - test and tune).

A speed density tune *should* handle this change without any issue at all... but this entirely depends on how accurate your IAT compensations are to fueling. If these are spot-on accurate (unlikely), then any change to the charge temp. (post-IC IAT) will be handled by the compensation table. The more likely situation is that your IAT compensation isn't spot-on and the fuel table will require some tuning (as well as accel. enrichment).

Speed density *can* run well at low RPM and idle, but it is more difficult to tune in this area. From a fuel economy standpoint, you will also use more fuel at idle and cruise using speed density on a safe tune. This is why hybrid blending algorithms are a thing - the MAF handles the low-load range and the speed density handles high load. The downside is that one of the biggest benefits to a speed density tune is that the motor can continue running if you get an air leak in the intake. On a MAF or hybrid tune, a post-MAF air leak will require a road-side repair or worse... a tow.

I would highly recommend tuning this yourself rather than relying on a tuner to do this. It's easy but will require a few revisions. A single e-tune looking at only one log is probably the worst way to do this.
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Old 11-09-2018, 04:30 PM   #8
CarmelValleyWRX
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there are spread sheets that will help tune a SD map. they will get you kinda close in most arias of the VE map. then you have to do a lot of logging and manual tuning to get it just right after that. beware that the spreadsheets will give weird results in some arias of the map that are hit during shifts and so on.
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