CarBerry ROM - 16bit Speed Density Project

dub c · **Joined:** Tue Apr 22, 2008 7:24 pm **Posts:** 2

Sorry to hop in and interrupt this thread.

Speed density question...

Question regarding IAT sensor and methanol jet placement...

-I have heard some conflicting information, the way I see it is the IAT sensor should be placed as close to the head as possible or at least midway through the runner (so heat from the valves isn't transferred), and the methanol near/before the throttle body.
So the cooler air charge going into the engine is measured by the IAT.

Contradictory information:
-In a MAF based system the airflow in doesn't change when the meth is spraying, the charge temp is just lower and the burn speed is slowed but the mani. pressure did not change with the methanol injection.
-In a SD system, if there is a significant drop in IAT, the IAT sensor will trigger the ECU to add more fuel when in fact the airflow into the engine isn't changing causing the car to run rich.

PLEASE HELP!

Hope I made sense.
Thanks in advance.

tachrev · **Posted:** Fri Apr 20, 2012 9:03 am

mrf582 wrote:

I've started logging FFB recently and I noticed this today... FFB is targeting 20AFR! and my AF correction goes through the roof max positive because my CL AFR target is 14.

I don't understand this. Why would the ECU do that? It starts off at 14.7 but as you maintain cruise, it gradually sneaks up to 20AFR FFB. Less than a minute's worth of cruising does this.

And look at the log's RPM, MAP, and TPS. Totally freaking steady-state in top gear. Yet the ECU is going crazy changing fuel around and f*** fueling to hell.

To clarify, I don't think this is a problem with this ROM only. I think some combination of my parameters is doing this most likely. But I'm posting here because maybe Carbibbles will be able to hack it and fix the factory s***.

I noticed this as well on my car, with a regular MAF setup.

Whenever I am maintaining speed, the FFB slowly creeps up...and up. My trims don't seem to be changing though, and my front o2 continues to report 14.7~.

Could it be in the logger definitions for FFB or something like that?

mrf582 · **Posted:** Fri Apr 20, 2012 10:24 am

purpose_built wrote:

The only major issue i have had thus far is not actually related to the rom. My car began stumbling from idle to 3k. I could only really feel it on low throttle input. Then it increased exponentially and my car would run lean above 1200. It turned out to be my coil was damaged and flooded the exhaust with un-burned air creating a lean reading on my gauge. I would have never found the problem if i were still running a maf sensor because the sensor or a leak would have been my first guess. Thanks again for this.

You're saying you only had a problem with your ignition coil at low loads/RPM but the car didn't misfire under boost? That is odd. Typically ignition issues are worse under higher loads/boost.

mrf582 · **Posted:** Fri Apr 20, 2012 10:32 am

dub c wrote:

-In a SD system, if there is a significant drop in IAT, the IAT sensor will trigger the ECU to add more fuel when in fact the airflow into the engine isn't changing causing the car to run rich.

Interesting point. Hadn't thought about this. And I suppose the result will be different whether you're injecting methanol or water. Since one is extra fuel while the other isn't.

Carbibbles · **Joined:** Tue Aug 30, 2011 3:17 pm **Posts:** 626

purpose_built wrote:

Thanks for this rom!!!! My car refused to run anything resembling right until i found this. It runs much smother with this than any other tune/tuner i have tried. I have a 03 hybrid built motor running a 8cm td06h/60-1. All i did was take your map that already existed and modified it a bit to mimic my old tune. After 7 days of beating the crap out of my car i have gone thru; a #3 ig coil,4 injector o-rings, a fuel pump, a heater hose, a turbo coolant hose and a alt. belt.

The only major issue i have had thus far is not actually related to the rom. My car began stumbling from idle to 3k. I could only really feel it on low throttle input. Then it increased exponentially and my car would run lean above 1200. It turned out to be my coil was damaged and flooded the exhaust with un-burned air creating a lean reading on my gauge. I would have never found the problem if i were still running a maf sensor because the sensor or a leak would have been my first guess. Thanks again for this.

Good to hear its working well for you

If you get any vids at the track post them up in the video thread!

dub c wrote:

Sorry to hop in and interrupt this thread.

Speed density question...

Question regarding IAT sensor and methanol jet placement...

-I have heard some conflicting information, the way I see it is the IAT sensor should be placed as close to the head as possible or at least midway through the runner (so heat from the valves isn't transferred), and the methanol near/before the throttle body.
So the cooler air charge going into the engine is measured by the IAT.

Contradictory information:
-In a MAF based system the airflow in doesn't change when the meth is spraying, the charge temp is just lower and the burn speed is slowed but the mani. pressure did not change with the methanol injection.
-In a SD system, if there is a significant drop in IAT, the IAT sensor will trigger the ECU to add more fuel when in fact the airflow into the engine isn't changing causing the car to run rich.

PLEASE HELP!

Hope I made sense.
Thanks in advance.

You want the IAT after the meth nozzle as you assumed (in the intake manifold is best). A drop in IAT means an increase in air mass, which means more oxygen; so it will need more fuel. This is why the ecu adds fuel as iat drops.

Volumetric airflow into the engine doesn't change but volumetric airflow into the colder area does increase. The increase in airflow into the colder (denser) area is what the MAF picks up on.

Carbibbles · **Joined:** Tue Aug 30, 2011 3:17 pm **Posts:** 626

Ill see if I can figure out the FFB stuff. If I remember correctly, merchgod said it wasn't exact and couldn't be used as a definite target AFR.

mrf582 · **Posted:** Fri Apr 20, 2012 3:52 pm

mrf582 wrote:

dub c wrote:

-In a SD system, if there is a significant drop in IAT, the IAT sensor will trigger the ECU to add more fuel when in fact the airflow into the engine isn't changing causing the car to run rich.

Interesting point. Hadn't thought about this. And I suppose the result will be different whether you're injecting methanol or water. Since one is extra fuel while the other isn't.

So IAT will drop but so will pressure. SD will figure it out.

The only thing you'll have to consider is the difference between methanol and water injection. You'll have to remove a lot more fuel if injecting methanol.

wrxrampage · **Joined:** Sat Apr 14, 2012 6:42 pm **Posts:** 3

Well, i got some more time in messing with the throttle kick and without it concerning the cooling during engine braking. i found that withou the kick she behaves normally and doesn't have the drastic cool down like it did with the .58v kick. after seeing that i didn't want to try the .74v cause i believe that it would be cooling faster ( allowing more air through the engine ). i'm currently loving the rom, and teetering on putting in the td06 20g on her.

would i need to rebuild a VE table or would it be able to work with what i have now? i'm looking to keep the boost levels the same, obviously higher in the rpm range. "td06"

ride5000 · **Joined:** Thu Aug 03, 2006 10:40 am **Posts:** 1031

your current VE table is a good start. i'd expect to adjust values slightly as it will likely be more efficient (ie less exhaust gas back pressure) and therefore show increased VE.

purpose_built · **Joined:** Thu Apr 19, 2012 9:15 pm **Posts:** 4

mrf582 wrote:

purpose_built wrote:

The only major issue i have had thus far is not actually related to the rom. My car began stumbling from idle to 3k. I could only really feel it on low throttle input. Then it increased exponentially and my car would run lean above 1200. It turned out to be my coil was damaged and flooded the exhaust with un-burned air creating a lean reading on my gauge. I would have never found the problem if i were still running a maf sensor because the sensor or a leak would have been my first guess. Thanks again for this.

You're saying you only had a problem with your ignition coil at low loads/RPM but the car didn't misfire under boost? That is odd. Typically ignition issues are worse under higher loads/boost.

It started out initially as a ridiculously small stumble almost like a hesitation. Then it increased to the point where the car couldn't see boost. It would cut in and out really quickly.

Carbibbles · **Joined:** Tue Aug 30, 2011 3:17 pm **Posts:** 626

moved the NLTS and shift knock discussion into their own threads.

GeneralTJI · **Posted:** Thu Apr 26, 2012 1:58 pm

whew.... was starting to think I'd really lost it

Tdagen · **Joined:** Wed Jun 25, 2008 8:09 pm **Posts:** 442

I'm just about to get my motor back in the car and I'm making a break in map, I'm going off my old group n rom. I'm wondering does the fuel injector scaling make global changes in the speed density base load comp. table?

I was running E85 the last time the car ran on the group n rom and now I'm gonna drain the tank and break in the new motor on 93. So I'm basically wondering if the injector scalar makes global fueling changes like the old maf roms do?

GeneralTJI · **Posted:** Mon Apr 30, 2012 1:08 am

yes it does

ckibue · **Joined:** Sun Apr 27, 2008 10:14 am **Posts:** 220

Hi all, thanks for the continuing developments and support. I have been running Ver. 3.6.5 for a few weeks now on a 2005 JDM STi. All is running well but I can't as yet figure out why my logged Engine Load is much less than the Engine load calculated from logged MAP, Engine RPM, IAT and settings in the corresponding Speed Density Tables in the Map. In my opinion, the Final Load Calc is more representative of the actual Engload when compared to logs of the same car with a MAF tune. See attached.

RomRaider

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