FMIC installed, now throttle delay?

voltic · 11-18-2012, 10:49 AM

Hey guys, I just did a Perrin FMIC install on my 12 STi, and now have a small issue I'm not really sure about. When I'm taking off, it seems like I have to add more throttle than usual, and it feels like there's a short delay. Anyone have any thoughts?

Other than that, I checked all connections and did a log while I drove it around the block. Everything looked good.

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findurpath · 11-18-2012, 10:59 AM

Turbo lag?

From Unabomber's FMIC FAQ:

What about the additional lag of a FMIC? This topic is highly debated. The two general trains of thought are:
1. FMICs increase turbo lag.
2. FMICs decrease throttle response.

jthatch12 · 11-18-2012, 11:07 AM

Quote:

Originally Posted by findurpath

Turbo lag?

From Unabomber's FMIC FAQ:

What about the additional lag of a FMIC? This topic is highly debated. The two general trains of thought are:
1. FMICs increase turbo lag.
2. FMICs decrease throttle response.

^this

brutnus · 11-18-2012, 11:08 AM

Turbo lag bro. The air has to travel much further so there is a slight delay.

findurpath · 11-18-2012, 11:12 AM

Quote:

Originally Posted by brutnus

Turbo lag bro. The air has to travel much further so there is a slight delay.

Exactly. Think about using a straw to sip a drink. What if you used a 2' long straw and threw some bends in it also?

brutnus · 11-18-2012, 11:16 AM

Granted it will work fine. You can also not have to worry about heat soak. Also if you ever plan on running more boost it won't be a problem.

RoadKillDMD · 11-18-2012, 11:20 AM

Professionally tuned?

subieguy87 · 11-18-2012, 11:46 AM

Quote:

Originally Posted by findurpath

Exactly. Think about using a straw to sip a drink. What if you used a 2' wide straw and threw some bends in it also?

Fixed it
Width not length

FLEX'N WRX · 11-18-2012, 02:59 PM

Turbo lag is not the correct term.

No variables have changed causing the turbo to spool any slower. The correct term would be delayed throttle response. The air is compressed at the same rate, but the air has to travel a longer distance.

drewvdw · 11-18-2012, 03:26 PM

Quote:

Originally Posted by subieguy87

Fixed it
Width not length

Both matter. I would've made a bong comparison (may get some points here

) bigger the bong the more fresh air you suck up before you get to the...er...tobacco smoke

opey · 11-18-2012, 03:41 PM

Quote:

Originally Posted by FLEX'N WRX

Turbo lag is not the correct term.

No variables have changed causing the turbo to spool any slower. The correct term would be delayed throttle response. The air is compressed at the same rate, but the air has to travel a longer distance.

which is just a fancy way of saying turbo lag

FLEX'N WRX · 11-18-2012, 03:58 PM

False... The turbo is not lagging

Ballistic1350 · 11-18-2012, 04:00 PM

someone else said it... is it tuned for the fmic? my guess would be no

LastResort · 11-18-2012, 04:01 PM

Quote:

Originally Posted by FLEX'N WRX

False... The turbo is not lagging

Quote:

Turbo lag is the time required to change power output in response to a throttle change, noticed as a hesitation or slowed throttle response when accelerating from idle as compared to a naturally aspirated engine.

turbo lag

FLEX'N WRX · 11-18-2012, 04:07 PM

You're misinterpreting the variables.

The turbo will naturally have characteristic lag. The lag that the OP is describing is not turbo lag. It is delayed throttle responses from the variable that did change. The longer pipes of the intercooler.

Your quote is irrelavant.

1wrxtra · 11-18-2012, 04:07 PM

Did you reset the ECU? Any time I do this my gas pedal's sensitivity changes. Your issue may be related your your FMIC but the way you describe it sounds exactly like what happens when you reset the ECU.

Tripintaz · 11-18-2012, 04:36 PM

You need a tune for a FMIC to remove the laggy throttle response.

voltic · 11-18-2012, 04:52 PM

Turbo lag when I shouldn't be producing boost? I'm going to guess the delay is just because of the longer piping as some have already said... this is also what I had assumed but wasn't sure. I'm pro-tuned with the stock TMIC, by the way.

It's not going to hurt anything if I run it like this for the next few weeks is it? Trying to delay a new tune until I get the rest of my goodie box under the hood.

LastResort · 11-18-2012, 04:57 PM

Quote:

Originally Posted by FLEX'N WRX

You're misinterpreting the variables.

The turbo will naturally have characteristic lag. The lag that the OP is describing is not turbo lag. It is delayed throttle responses from the variable that did change. The longer pipes of the intercooler.

Your quote is irrelavant.

The quote is completely relevant, because it treats turbo lag as a characteristic of the system. Which includes the motor, piping, etc and is based on actual output vs. your metric which isn't really realistic. Which is pretty much the only relevant metric, because a turbo doesn't have lag, it has an inertia and frictional losses. The same turbo in two different applications, will have different lag.

RoadKillDMD · 11-18-2012, 05:47 PM

Quote:

Originally Posted by voltic

Turbo lag when I shouldn't be producing boost? I'm going to guess the delay is just because of the longer piping as some have already said... this is also what I had assumed but wasn't sure. I'm pro-tuned with the stock TMIC, by the way.

It's not going to hurt anything if I run it like this for the next few weeks is it? Trying to delay a new tune until I get the rest of my goodie box under the hood.

Get a tune... ASAP. You can drive around, but stay off the throttle and out of boost. There's a reason you're feeling this 'delay'. Your fueling is tuned for a TMIC. With the FMIC, boost takes a little longer to get to your engine, so it's creating a 'choppy' section in your power band that can be smoothed out with a tune. Resetting your ECU will not magically fix this...

FLEX'N WRX · 11-18-2012, 06:12 PM

Quote:

Originally Posted by LastResort

The quote is completely relevant, because it treats turbo lag as a characteristic of the system. Which includes the motor, piping, etc and is based on actual output vs. your metric which isn't really realistic. Which is pretty much the only relevant metric, because a turbo doesn't have lag, it has an inertia and frictional losses. The same turbo in two different applications, will have different lag.

Youre on a tangent now...

The quote compares a turbocharged application to a NA application.

The OP described an issue. The relevant parts of the system that alter the spooling characteristics have not been touched. The natural lag associted with the system is still present. The turbo is not lagging anymore than it did prior to his fmic install. To say the cause is turbo lag is incorrect. The culprit is throttle response, and the need for a tune to account for the pressure drop in the system.

Uncle Scotty · 11-18-2012, 06:45 PM

Quote:

Originally Posted by voltic

Hey guys, I just did a Perrin FMIC install on my 12 STi, and now have a small issue I'm not really sure about. When I'm taking off, it seems like I have to add more throttle than usual, and it feels like there's a short delay. Anyone have any thoughts?

i guess you figured out why a fmic may not be the best idea, didnt ya??

voltic · 11-18-2012, 07:13 PM

Quote:

Originally Posted by Uncle Scotty

i guess you figured out why a fmic may not be the best idea, didnt ya??

Despite my insatiable need for approval from people I don't know, I was looking more for answers as to whether this was a problem or a common thing.

sense of nature · 11-18-2012, 08:08 PM

Quote:

Originally Posted by Tripintaz

You need a tune for a FMIC to remove the laggy throttle response.

^ This makes me

mod maniac · 11-18-2012, 08:32 PM

It seems to me throttle response (engine responding to the throttle petal being pushed) and turbo lag (the time it takes the turbo to build boost) are two different things. Is the op complaning about the off boost response or the delay in boost? It does need a tune ether way.

11-18-2012, 10:49 AM	#1
voltic Scooby Newbie Member#: 310385 Join Date: Feb 2012 Chapter/Region: MAIC Location: Fredericksburg, VA Vehicle: 2013 Rising Blue 4D Golf R	FMIC installed, now throttle delay? Hey guys, I just did a Perrin FMIC install on my 12 STi, and now have a small issue I'm not really sure about. When I'm taking off, it seems like I have to add more throttle than usual, and it feels like there's a short delay. Anyone have any thoughts? Other than that, I checked all connections and did a log while I drove it around the block. Everything looked good. * Registered users of the site do not see these ads.

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11-18-2012, 10:59 AM	#2
findurpath Scooby Specialist Member#: 277487 Join Date: Mar 2011 Chapter/Region: NWIC Location: Bozeman, MT and Lakewood, WA Vehicle: 2006 CGM WRX Limited 6sp, 18G, Phatron tuned	Turbo lag? From Unabomber's FMIC FAQ: What about the additional lag of a FMIC? This topic is highly debated. The two general trains of thought are: 1. FMICs increase turbo lag. 2. FMICs decrease throttle response.

11-18-2012, 11:08 AM	#4
brutnus Scooby Newbie Member#: 257195 Join Date: Sep 2010 Chapter/Region: South East Location: Hixson Vehicle: 2004 WRX 2.1L 12k miles strong	Turbo lag bro. The air has to travel much further so there is a slight delay.

11-18-2012, 11:16 AM	#6
brutnus Scooby Newbie Member#: 257195 Join Date: Sep 2010 Chapter/Region: South East Location: Hixson Vehicle: 2004 WRX 2.1L 12k miles strong	Granted it will work fine. You can also not have to worry about heat soak. Also if you ever plan on running more boost it won't be a problem.

11-18-2012, 11:20 AM	#7
RoadKillDMD Scooby Specialist Member#: 284792 Join Date: Jun 2011 Chapter/Region: RMIC Location: Vanilla Valley, CO Vehicle: 2011 STI Plasma Blue Pearl	Professionally tuned?

11-18-2012, 02:59 PM	#9
FLEX'N WRX NASIOC Supporter Member#: 163672 Join Date: Nov 2007 Location: Where the sidewalk ends... Vehicle: GV Same color as veneers	Turbo lag is not the correct term. No variables have changed causing the turbo to spool any slower. The correct term would be delayed throttle response. The air is compressed at the same rate, but the air has to travel a longer distance.

11-18-2012, 03:58 PM	#12
FLEX'N WRX NASIOC Supporter Member#: 163672 Join Date: Nov 2007 Location: Where the sidewalk ends... Vehicle: GV Same color as veneers	False... The turbo is not lagging

11-18-2012, 04:00 PM	#13
Ballistic1350 Scooby Newbie Member#: 156877 Join Date: Aug 2007 Chapter/Region: Tri-State Location: North Wales, PA Vehicle: 04 sti	someone else said it... is it tuned for the fmic? my guess would be no

11-18-2012, 04:07 PM	#15
FLEX'N WRX NASIOC Supporter Member#: 163672 Join Date: Nov 2007 Location: Where the sidewalk ends... Vehicle: GV Same color as veneers	You're misinterpreting the variables. The turbo will naturally have characteristic lag. The lag that the OP is describing is not turbo lag. It is delayed throttle responses from the variable that did change. The longer pipes of the intercooler. Your quote is irrelavant.

11-18-2012, 04:07 PM	#16
1wrxtra NASIOC Supporter Member#: 316364 Join Date: Apr 2012 Chapter/Region: MAIC Location: Central PA Vehicle: 2012 WRX	Did you reset the ECU? Any time I do this my gas pedal's sensitivity changes. Your issue may be related your your FMIC but the way you describe it sounds exactly like what happens when you reset the ECU.

11-18-2012, 04:36 PM	#17
Tripintaz Scooby Specialist Member#: 245218 Join Date: Apr 2010 Chapter/Region: South East Location: FL Vehicle: 2013 STI Limited Ice Silver	You need a tune for a FMIC to remove the laggy throttle response.

11-18-2012, 04:52 PM	#18
voltic Scooby Newbie Member#: 310385 Join Date: Feb 2012 Chapter/Region: MAIC Location: Fredericksburg, VA Vehicle: 2013 Rising Blue 4D Golf R	Turbo lag when I shouldn't be producing boost? I'm going to guess the delay is just because of the longer piping as some have already said... this is also what I had assumed but wasn't sure. I'm pro-tuned with the stock TMIC, by the way. It's not going to hurt anything if I run it like this for the next few weeks is it? Trying to delay a new tune until I get the rest of my goodie box under the hood.

11-18-2012, 08:32 PM	#25
mod maniac NASIOC Supporter Member#: 300551 Join Date: Nov 2011 Chapter/Region: SCIC Location: mariposa ca. Vehicle: 2002 DD wgn 6 spd 2.1 kel 272's meth 2.5xtr	It seems to me throttle response (engine responding to the throttle petal being pushed) and turbo lag (the time it takes the turbo to build boost) are two different things. Is the op complaning about the off boost response or the delay in boost? It does need a tune ether way.