Air density correction - new method

Testing and development of Megasquirt 3

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Re: Air density correction - new method

Postby GintsK » Fri Nov 11, 2011 1:31 am

Ambient air sensor? Most cars have not them. Hondas!

You knew what this sensor will measure? Intermediary - fuel temperature! So more sense is to measure fuel temperature directly. There we can really see 10% deviation from frost temperatures to engine temperatures... This is why we see lean condition after 15 minutes restarting on hot engine!

And anyway last decade we see more and more returnless fuel rails in OEM. How they handle keep stoich before oxygen sensor is ready?

Regarding air density. I wrote it here before:
1) avoid from stupid sensors what measure manifold temperature! This one is best what I found: Image

2) mount sensor as close as possible to intake valves and in flow [usually in manifold after the throttle]. Sensor should measure not ambient temperature, but temperature of air passing to cylinder!

3) make additional 2D or make current as 3D table for gas law correction: from MAT (we have it) and from air mass flow (like VE*rpm).
More air passes the sensor, model becomes more close to ideal gas law.

In general this is very important basement for fuel injection. I am disappointed - MS nowadays has tons of smart features. But it worth nothing if we have difficulties to keep fueling as WE want.

Gints.
Some of my instalations:
VW TBI, VW 16V 60-2,
BMW M50 COPs 60-2, BMW M20 and M50 ITBs as Alpha-N, BMW M20 turbo Wasted spark
Opel 20XE Wasted Alpha-N with ITBs
Audi 10VT Audi20V
MR2 3S-GE.............
and over 100 tuned
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Re: Air density correction - new method

Postby Peter Florance » Fri Nov 11, 2011 4:42 am

GintsK wrote:Regarding air density. I wrote it here before:
1) avoid from stupid sensors what measure manifold temperature! This one is best what I found: Image

Gints.

How about a part number? I went to foxmotors site but I don't read Russian. :RTFM:

Thanks!
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Re: Air density correction - new method

Postby Black99rt » Fri Nov 11, 2011 5:22 am

I like the looks of that sensor!

Definitely get us a PN.
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Re: Air density correction - new method

Postby winstonusmc » Fri Nov 11, 2011 5:53 am

For those that are Google impared:
http://www.autozone.com/autozone/parts/2003-Audi-A4-Quattro/Air-Charge-Temperature-Sensor/_/N-jjzoaZ9gsls
Audi/Volkswagen 1.8t among others.....
Cheap at $44 American. I might get one instead of the GM unit for my ITB install.

Big question though, can it handle getting fuel on it?
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Nissan Silvia S14 RB25DE ITB/NA ran MS3/MS3X w/ factory Mitsubishi CAS (disassembled)
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Re: Air density correction - new method

Postby GintsK » Fri Nov 11, 2011 6:15 am

Sorry picture was first result from google.

PN: Bosch 0 280 130 085 = VAG 058 905 379

here is some deeper data. Note: it is really really fast! http://www.bosch.com.au/content/languag ... rature.pdf

It handle non-conductive fluid on it. Glass thermistor. Connections - welded.

Gints
Some of my instalations:
VW TBI, VW 16V 60-2,
BMW M50 COPs 60-2, BMW M20 and M50 ITBs as Alpha-N, BMW M20 turbo Wasted spark
Opel 20XE Wasted Alpha-N with ITBs
Audi 10VT Audi20V
MR2 3S-GE.............
and over 100 tuned
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Re: Air density correction - new method

Postby nuvolarossa » Fri Nov 11, 2011 7:09 am

GintsK wrote:. I am disappointed - MS nowadays has tons of smart features. But it worth nothing if we have difficulties to keep fueling as WE want.

Gints.

Affermative.
I had a lot of difficulties keeping fuel as I'd like between hot/cold and high/low altitudes, and I know a lot of other MS users had troubles too.
In the end I had no more time to play with so I parked temporarily the MS3 project from DD and relegated it to the track car.

Mainly it depends where you live, if you live in a uniformly flat area (regarding altitude) you'll rarely have this kind of troubles so often...

having a car tuned and running is one thing, having it running 100% perfect all the year as the stock ecu without having to check every time AFR or connect pc to make mods, well that's another world.
That's why OEM needs YEARS to make the definitive tune to a new engine.

I would be curious how other "cheap" aftermarket ecus deal with this.

(this is one of those small reasons some people don't choose MS)
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Re: Air density correction - new method

Postby Dennis930 » Fri Nov 11, 2011 8:58 am

Peter Florence wrote
How about a part number? I went to foxmotors site but I don't read Russian.



I bought mine from 034 Motorsports, under Engine Management assessories for $35.00. You might also try auto parts stores.

-Dennis
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Re: Air density correction - new method

Postby piledriver » Fri Nov 11, 2011 9:19 am

... a lot of difficulties keeping fuel as I'd like between hot/cold and high/low altitudes, and I know a lot of other MS users had troubles too.


Note that most of THE solution for this is the same one that many (most? All?) OEMS use now--- a (Ford) MAF sensor WILL work with MS.
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Re: Air density correction - new method

Postby Keithg » Fri Nov 11, 2011 10:06 am

a MAF is not the 'only way'. A MAF is used in conjunction with MAP to ensure EPA and to have a tolerant system. Saab Trionic 5 uses MAP only and does not seem to have trouble with altitude. IT does also use the ambient temp as well as a MAF in the intake tube between intercooler and throttle and a MAP on the intake manifold.

An MS with a MAP sensor, an ambient pressure sensor and WB02 should have enough inputs to compensate for altitude adequately. Is this still truly a problem? I live in 'flat landia' and have not tried taking my car up a mountain, yet.

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Re: Air density correction - new method

Postby Black99rt » Sat Nov 12, 2011 12:16 pm

Plenty of chryslers don't use MAF sensors. Including the model based NGC controller (srt-4 and others) even the newest HEMI stuff.
1999 Dakota 5.9L R/T-
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Re: Air density correction - new method

Postby piledriver » Sat Nov 12, 2011 3:06 pm

Black99rt wrote:Plenty of chryslers don't use MAF sensors. Including the model based NGC controller (srt-4 and others) even the newest HEMI stuff.


Yes, but Chrysler has hordes of engineers and $1M environmental chamber dynos on which to fine tune.
(as well as test tracks etc)

Just sayin... MAF (or maf/map hybrid) is logically more sensible.
What I DON'T know is if that translates to reality with MS, as I have not tried it. yet.
(I also live in flatlandia, so it's academic for me, SD with second baro works peachy)
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Re: Air density correction - new method

Postby James » Sat Nov 12, 2011 5:29 pm

I am currently preparing some ITBs to "upgrade" from the single throttle body I have now.

There are two holes in each one that I need to block up where I have removed some secondary butterflies — they are before the main butterflies.

Could the 0 280 130 085 sensor mount in one of these holes? It seems sensible that it would be measuring the IAT nicely at that point.
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Re: Air density correction - new method

Postby piledriver » Sat Nov 12, 2011 7:58 pm

If you are running the GSXR TBs or similar, it's probable, but the image has no dimensions.
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Re: Air density correction - new method

Postby GintsK » Sun Nov 13, 2011 1:22 am

piledriver wrote:If you are running the GSXR TBs or similar, it's probable, but the image has no dimensions.

pdf has detailed drawing of the sensor with all dimensions!
Some of my instalations:
VW TBI, VW 16V 60-2,
BMW M50 COPs 60-2, BMW M20 and M50 ITBs as Alpha-N, BMW M20 turbo Wasted spark
Opel 20XE Wasted Alpha-N with ITBs
Audi 10VT Audi20V
MR2 3S-GE.............
and over 100 tuned
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Re: Air density correction - new method

Postby James » Sun Nov 13, 2011 3:07 am

It calls for a 12.5mm hole — which is the right size for one of the holes that has a bush.

It would stick it in the perfect place right in the middle of the throttle body — assuming it will survive there and not impede airflow too much.

My question was more about suitability.
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Re: Air density correction - new method

Postby ol boy » Sun Nov 13, 2011 12:08 pm

I had a though.. why not add MAT to the EAE formula? There's 2 clt tables already there just add 2 more for MAT. For those not running EAE they would just be stuck with the current correction %value and table. Once I get my WB fixed I'm going to switch over to EAE and give it ago.

Later Ryan
289 SBFord, Dual GM TBI, 8 LS2 coils in waste spark and a TURBO!, MS2extra 3.3.0alpha10 code
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Re: Air density correction - new method

Postby muythaibxr » Sun Nov 13, 2011 3:41 pm

ol boy wrote:I had a though.. why not add MAT to the EAE formula? There's 2 clt tables already there just add 2 more for MAT. For those not running EAE they would just be stuck with the current correction %value and table. Once I get my WB fixed I'm going to switch over to EAE and give it ago.

Later Ryan


Mainly because MAT is already part of the fuel equations so it already affects EAE.
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Re: Air density correction - new method

Postby ol boy » Sun Nov 13, 2011 4:08 pm

"If" added to EAE would you do a load vs temp table or temp vs rpm table or both? I'm wondering if moving all enrichment's/corrections into one broad theme like EAE would also solve baro, and MAT correction. What would it be called.. a 6D table?
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Re: Air density correction - new method

Postby 88TurboDad » Wed Apr 25, 2012 11:29 am

I feel the current method is just fine the real issue is the sensor location. I moved my sensor to right after my air filter and retuned the truck and it ran great when I tuned it at 20degs and checked it again at 75degs and the AFR was almost perfect. The amount of heat that the air absorbs will stay consistant for a given air volicity so the VE table will take care of the heat the air asorbs. This is with a 2.3 turbo ranger running 30psi of boost,water/meth injection. The truck is driven daily 150 miles a day and has 90,000 miles of mega squirt driving. It just recently passed emisions with the sensor by the air filter .
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Re: Air density correction - new method

Postby piledriver » Wed Apr 25, 2012 7:12 pm

I tend to agree.

I have my MAT sensor mouned NEXT to the air cleaner, mounted to the body of the car, so it's basically reading the ingested air temp.

No significant AFR variation issues from 10F to 110++F temps.

Details:My modified factory manifold is steel tubing with a steel sheetmetal plenum, so it's reasonably thermally isolated from the engine, only direct contact is via the studs at the heads.
Even the manifold ends have an ~8mm bakelite thermal isolation gasket from the factory to reduce hot restart issues due to fuel boiling in the injectors.
(aircooled heads run hotter than water cooled, usually)

I have been considering adding either ceramic heat reflective coating or a thermal blanket between the block and the plenum.

If you have a hot manifold, either from direct manifold heat or thermal transfer, there may be a better location, but only experimentation will find it.
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