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Discussion Starter #1
The reason I ask is, I have the GReddy 15G kit waiting to go on my D16y7 and I was planning on running the y8 240cc injectors with the Emanage instead of my stock 190cc's. The problem I forsee is the car running way too rich at idle and in closed loop. Am I right in thinking this or will the car run fine if the injector size is set to 240 through the emanage? Thanks!
 

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The reason I ask is, I have the GReddy 15G kit waiting to go on my D16y7 and I was planning on running the y8 240cc injectors with the Emanage instead of my stock 190cc's. The problem I forsee is the car running way too rich at idle and in closed loop. Am I right in thinking this or will the car run fine if the injector size is set to 240 through the emanage? Thanks!
easy fix.
get rid of the emanage.
get a chipped ecu. it will make it run way better
 

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now now...don't be hating on the emanage group...some like it and some don't (i know piggy backs SUCK, but if that's all you got, then...)

as for your question, it all depends on the tune...granted emanage, while a good system for what it is, is still a piggy back system so there for flawed...if you can afford to do so I would also recomend using a chipped ecu for a better tune...however if this is not an option someone else will have to chim in, for i have no real experience with piggy backs...
 

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Discussion Starter #4
Believe me, I am well aware of doing an obd1 conversion but for reasons I don't really want to get into, I will be running the e-manage for a while.
 

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let me help you out if i can.

With a piggy back system that still runs closed loop obd2, the oxygen sensors are going to try as much as they can to get you to 14.7 air fuel ratio. When u change injectors, depending on the size you change your car MIGHT be able to still idle at 14.7 because of the feedback from your o2 sensors, will change your Short term fuel trim (STFT) and Long term Fuel Trim (LTFT). If you use the piggy back to scale back the injector percentages, you still have to check STFT and LTFT with an ODB2 scan tool, to make sure these values are close to zero. Otherwise your tune will change over time because of the oxygen sensors affect on STFT and LTFT.

In emanage (which i have never used) if you can set the injector size to 240 (if you end up using 240cc injectors) then do it. It wil scale back injector percentage to try to get the STFT to zero..but its only an estimate of old injector size divided by new injector size minus one. Your fuel trims might still be nonzero though.

I'm by no means an expert but that is my understanding.
 

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oh and let me post that as it backs up what i am saying. be sure to note the LTFT.

Remember, if you have not scaled your injectors right in closed loop, it will eventually change yopur LTFT..you're thinking, oh big deal.. well no.. because when you go in open loop..your AFR will change based on what the LTFT. LTFT is stored in your ECU's memory.

Lets do this in an example.

You have your car with emanage in it, and you want to change the injectors from 190cc to 240cc. In your piggy back system you input old injector size and new injector size, and it performs the calculation i gave above in order to figure out it needs to reduce your injector pulse width by 20%.

You hook up your wideband...and your car now seems to still be idling at 14.7, and you think awesome...lets tune this thing for boost since it seems to drive normal at 14.7.

You go and do a few pulls at 5psi..and get your AFR dialed in at 11.5 say.

However there is an evil lurking which you dont know about LTFT and STFT.

What you did not know is at idle..your percentage of 20% reduction was too low..meaning the injector pulse width was too low.. causing a lean condition, but your o2 sensors picked it up and incresed your injector pulse width for you by say 5%, and at the time your STFT would be +5%, say you let the car idle for only like 5 minutes..then you go tuning..

You start adjusting fuel as you see fit until you reach 11.5. However lets say you reset your battery before u began all this, so your LTFT would have been erased from the ecu's memory. So its at zero. You tune the car to 11.5 and say sweet my car is now tuned on the piggy back for 5psi.

Well 2 weeks later..you happen to hook your wideband back up..and notice jesus...under boost your afr's are now like 10.0, and you think WTF, i jusst tuned it for 11.5.

Remember how i said your STFT was +5%...now after a while the ecu changed your LTFT to +5...and since the ECU still uses LTFT under open loop (when your boosting), your car has now added 5% to your injector pulse width under boost, which account for your 10.0 AFR.

What would be worse, is say you were originally on the other side of the STFT, and it was -10%. then your LTFT changed to -10%...then you'd be 10% leaner, and potentially blow up your engine!!!

The lesson is..get your short term fuel trims as close to zero as possible in closed loop, so your LTFT stays close to zero. To do this, hook your obd2 scan took up, and monitor your STFT as you adjust the pulse width percentages at idle...1500rpm 2000 rpm..3000rpm etc..trying to make it as close to zero as possible.

That way your LTFT stays close to zero and your tune doesn't change!

I have more ways i making accurate changes, and helping your car react better when starting to spool..say your car is still in closed loop and trying to maintain 14.7, but needs more fuel because your starting to boost.

You have to do some tests which i can explain in a lter post, and must have the ability to modify o2 bank voltages in order to make the car react better in these scenarios..
units like the AEM FIC can do this.

Sorry i wrote so much, but i hope it helps some people understand some stuff!
 

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Discussion Starter #8
honestly after reading that I am considering buying a chipped ecu from phearable with the conversion harness. I was planning on just running the stock 5.5 psi and figured that the emanage is pretuned for 240 injectors so if I swapped 240s I would be all set but it sounds like that's not the case.
 

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don't get me wrong.. if the emanage is very accurate in its scaling your fuel trims might be okay.
I don't really know because i dont have experience really using piggy backs like that. this is just my experience from using them on other cars.
Mostly the AFC, SAFC, AEM FIC
 
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