RomRaider

Hi,

Running a Version 8 ej207 with carberry rom and full speed density. Just temporarily we have the sensor plumbed into the turbo inlet only 5 inches or so behind the air filter. My thoughts behind using this location, was that the factory air flow meter had an intake air temp sensor here, so it should be good enough to drive around and take some logs and get the car dialed in.

I'm just trying to wrap my head around the scaling and what the ideal location should be and why. Also I believe this sensor is an NTC type was the factory also an NTC?

As of now the car runs, drives, idles and pulls fine. I have some high long term fuel trims and a few spots when cruising and tip-in that need attention but otherwise the car drives awesome.

here's what i know - all ej205 and ej207 roms, regardless of WRX, STi, S20x versions, or group N, all have the same intake sensor scaling.

the group n manifolds at least had a sensor plumbed in the manifold, and ej207s can be seen with the spot ready to be drilled for a sensor.

as to what sensor is used, what type it is, and if it is identical in response to the thermistor setup in the MAF housing, I do not know.

pull over all the IAT related compensations from a MAF equipped stock ROM such as an STi version or S203, etc.

and then play around with IAT/SD load compensation if on speed density. start at all 1s and when the vehicle is fully warmed up (coolant, oil, trans, etc.) compare fueling error of a certain load and rpm against IAT and determine the IAT load compensation.

if using MAF mode, then scale away.

what sensor did you use again? do you know what the scaling is for it or are you trying to stab at it?
why not just use a haltec or aem 1/8 npt fast thermistor? the scaling is known (thanks Lance), and even the supplied scaling isn't bad but isn't too accurate with our ecus.

Generally in performance applications the IAT sensor is placed after the intercooler for actual air temperature entering the engine (recommended for high boost applications).

Hey thanks for the reply man,

This car does have a seperate IAT in the intake manifold and to my understanding it was only for auto intercooler function.

I have been playing around with the scaling but I think short term I will relocate this sensor into the intercooler endtank (topmount) until I get a front mount where then I will move it just in front of throttle body and try that.

Ok,

So for now I relocated the IAT to the intercooler and going to rescale the table tonight. I have another question.

Do I make any changes to the speed density load compensation tables? Could someone describe this tables purpose to me as well as IAT port temp estimation and determination tables.

I'm not full retard but sometimes I need to simplify things in my head to break them down and fully understand.

Thanks,

So I've scaled the IAT and I'm still having the same driveability issue so I'd like to explain and provide the information about the car and show a log and maybe some can point me in the right direction. I want to mention my wideband doesn't work with RR logger its a weird AEM unit not a uego so this is tricky I know, but you'll have to trust me when I say its bogging and showing as lean as 17:1. I've tried to narrow the log down to just when the issue occurs so this is just sitting at idle and then abruptly stabbing the throttle. When going down the road to get this issue to happen the car needs to be loaded up in a higher gear and punch the throttle. I almost have to induce this condition with normal smooth throttle inputs it doesn't happen. It seems like the "speed" of enrichment isn't fast enough or something.

-The issue is a really lean condition when I stab the throttle quickly, overall driveability is good and shortly after the initial lean "bog" happens the car pulls great and AFRs are plenty safe @ 10.8-11.0

-V8 EJ207 stock twinscroll turbo (vf37 I believe) max boost is 20psi
-Walbro 255lph in tank pump, modified 02WRX injectors flow tested by witchhunter performance to 830cc.
-No Maf at all, full speed density, AEM IAT tapped into top mount intercooler end tank.
-Engine has been boost leak tested, smoke tested with no leaks, and no fault codes stored In ECM
-3 inch downpipe with wideband and factory AFR sensor about 4 inches behind the turbo.

Oh and I should mention I have the injector flow scaling @799cc I didn't touch the latencies because I believed it wasn't necessary as the injectors are stock modified units.

injector latency does change though when you modify injectors, I've tuned several sets.

it sounds like you are having issues with tip-in enrichment, and using the ve table to compensate for loose injector data.

in most stock subaru roms, even if the table is present, rpm compensation is not being used for tip-in-enrichment.

^ this really helps tip-in enrichment though.

I suggest rescaling your VE table, starting at wastegate pressure and focusing on closed loop area, with a lot of detail spent trying to get as much of the table up to and at wastegate pressure verified. then start to increase pressure and continue to scale and check accuracy until you are at or above peak desired pressure. many times people check idle and some of closed loop and then tune WOT, without doing anything in between.

if you don't have the transitional area between cruise and full boost accurately scaled, you could chase around in circles for a lean spot that is actually because of the difference for the VE table compensating for 'off' injector data.

post up your rom and i'll update TIE and add port temp estimation, which once the ve table is scaled, really helps with getting smaller fuel trims for closed loop.

Ok cool thanks for the info jon that clears up a few things. I'll post up the rom later. So I started by changing the flow scaling to 815cc and I'm going to increase the latencys in small increments until fuel trims are closer to 5% (they are at -15 long term right now) then, scale the VE table.

That sound like a good star? at wastegate pressure like you said.

Here's my rom. I'm only making changes in small increments but it feels like it's doing absolutely nothing. Still cruises and idles the same WOT pulls are good but if I have to stab the throttle up hill it goes so lean and bucks like crazy.

Next week I'm going to drive around with a fuel gauge hooked up and make sure I don't have a lazy fuel pump or something.

I found a good thread on here with a gentleman and his woes with modified blues. I'm gonna keep messing with the latency table and see where I end up.

but there aren't any woes really, latency is known. the ballpark is known. you can be off by 0.03 ms either way and compensate in the VE table and have the same fueling error at the end of the day.

everyone is new some time, and I don't know everything.

so as a side note to SD/load compensation, i believe the stock SD/load comp scaling is actually intended for the sensor in the MAF. having poured over Cobb documents over the years I found a calibration pdf. that is still available if you search hard enough. In that one, an example table in a blended capable SD/MAF tune shows a scaling similar to the stock group N rom (Carberry is a patch that adds stuff to the ROM, after it is patched it is still containing tables intended for group N.) where the biggest difference is that the table is centered around 86 degrees F instead of 104 degrees F with minor deviance, enough to show it's essentially 'the same'. This combined with the temp sensor scaling being the same between all 16 bit EJ engines, leads me to believe the one in the manifold is not used for VE.

here are two articles that you should read concerning sd/load and port temp estimation:
2.0L speed density tuning guide from Cobb
this thread on RR: http://www.romraider.com/forum/viewtopic.php?f=36&t=9314&hilit=MAT+Sensing

Port temp estimation attempts to correlate some math between the airflow of the engine versus the difference of temperature between the IAT sensor and Coolant temp sensor, as the air at lower airflow has a higher temperature entering the cylinder than at higher airflow.

I don't have enough time to go over the whole ROM, which I can do later, but scalar of 820 to 840 on ethanol free pump gas and latency of

to start. you might find a little bit less, or a little bit more is more accurate, but you'd probably run around in circles if you spent enough time on it. settle in the middle. there are lots of great articles about latency tuning.

I can throw other changes your way tomorrow after work, but for tonight I've got to hit the bed.

I didn't want to open a new thread to ask this but has anyone successfully used this wideband with rom raider logger?
https://www.google.com/search?q=aem+fai ... 4261046043

I've tried every AEM plugin on the romraider logger with no luck. On two other cars I have used innovate wideband with no issue so maybe this AEM unit in particular isn't compatible? I am gonna swap out my USB adapter just incase to rule that out.

woops nevermind used the S E A R C H button haha what a newb I am sometimes I had to dig to find it but looks like I'm SOL.

use the 0-5v out going to an unused sensor
such as the maf voltage reference line if you aren't using mass airflow
or the tgvs if they are deleted and codes are turned off
or the rear 02

a little bit of math on the logger definition and you can now log wideband in lambda or gas AFR, etc.