MAF Scaling wrong - stock MY07

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MAF Scaling wrong - stock MY07

Postby lockytaylor » Sun Jul 17, 2011 9:16 pm

Hi All,

I seem to have a problem with my stock ADM MY07 WRX. I have been logging it over the last few weeks with the objective of doing a stage 1 on it in the near future and I want to make sure the car is ok before doing so. Through one of the very helpful guides that has been developed, the author suggested that I make sure my MAF scalings are correct before going any further and it seems I do in fact have a problem.

After resetting the ECU and allowing it to settle in (couple of days normal driving), I am finding that Learning View and ROM Raider are telling me that I am running rich across all scales (A-D) by about anywhere from -8% to -11%. It seems that the car is pulling fuel and I am at a loss as to why. As mentioned, the car, intake and the map are both completely stock. Still even using the stock air filter.

I was wondering whether one of you tuning gurus might be able to give me some pointers on trying to rectify. Couple of things that may help:

Running 98 ron (same as us 93?)
I'm a semi high climate - 600 metres ASL
Temps are currently quite low (winter) and these measurements have been in temps of freezing up to 12 degs.
Recently cleaned the MAF sensor with sensor cleaner - made no difference.

Thanks. I look forward to your reply.

Lachlan.
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Re: MAF Scaling wrong - stock MY07

Postby ukwrx » Tue Sep 04, 2012 12:54 pm

I've got exactly the same issue on my 06 WRX. Any body got any ideas please,before I am forced to rescale my maf to resolve, as I am pretty sure you should not have to do this on a stock setup.

thanks
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Re: MAF Scaling wrong - stock MY07

Postby throttlehappy » Sat Sep 15, 2012 4:21 pm

Stock tune runs rich, hence why the fuel table runs rich. It self learns to lean out the open loop fuel table :)
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Re: MAF Scaling wrong - stock MY07

Postby lockytaylor » Sat Sep 15, 2012 10:52 pm

Hi,

Thanks for the reply but not this rich. I now get -10% to -15% across each bank of the fuel trims. And it is no longer stock, now a stage 2 with k&n filter and snorkels delete.

I have so far raplaced my MAF (twice), front o2 sensor, rear o2 sensor (all new) to no avail. I have also done a full system pressure test and there are no major leaks.

I have just ordered new spark plugs - need replacing anyway - last resort really - runs very rich - surges sometimes and blows black smoke on boost.

Only advantage - no knock....

Lachlan.
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Re: MAF Scaling wrong - stock MY07

Postby ukwrx » Sun Sep 16, 2012 10:52 am

Thats interesting you have already replaced these parts, as I was considering that too. I've read that it could be leaking injectors/fuel regulator, or even cracked ringlands causing excess blowby or head gasket leaking coolant. Internet can be scary.

But if I did not have an ODB2 or learning view, I would not know there could be a problem as the car runs fine. I'm pretty sure your k&n wont help. Have you looked at the STI MAF scaling its different even though all the intake is the same. Could be worth a try? i'm looking at this too. I have tried the romraider maf scale but not flashed it yet, as I don't want to mask over if this is a problem with the fueling rather than the air.
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Re: MAF Scaling wrong - stock MY07

Postby lockytaylor » Sun Sep 16, 2012 4:48 pm

Hmmm. Interesting. Didn't know that the STI MAF scaling were different. One thing though, are the STI and WRX intakes exactly the same? Ie. are the ysame MAF sensor and/or o2 sensors? I know both front and back O2 sensors on the 06/07 WRXs use the rear O2 as well as the front O2 for fuel, but not sure the STI does.

The other possibilities are a bit scary though but hopefully rings would blow smoke all the time and a blown head gasket would show up in the oil (white creamy look to the oil?)...

Fuel injector is a possibility - might get them checked out. Always run premium fuel but can't vouch for the guy who owned it before me.

Lachlan.
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Re: MAF Scaling wrong - stock MY07

Postby ukwrx » Sun Sep 16, 2012 10:40 pm

Looking at the part numbers on opposed forces, the intakes seem to be identical (housing/filter/maf sensor). My understanding is only up to the maf is important for scaling? The maf scale is simply converting the voltage into airflow, so i cant see how a different o2 should affect the values.

Wrx

http://opposedforces.com/parts/impreza/ ... tration_2/

Sti

http://opposedforces.com/parts/impreza/ ... tration_2/

Do you know any one else with a wrx to compare, apart from mine! How many miles has yours done?
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Re: MAF Scaling wrong - stock MY07

Postby ukwrx » Mon Sep 24, 2012 10:31 pm

Have you managed to replace your plugs yet? I did a low pressure intake test, no leaks found. Still running -10% in A. :evil:
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Re: MAF Scaling wrong - stock MY07

Postby lockytaylor » Mon Sep 24, 2012 10:43 pm

Yes done the plugs - still the same! Even replaced with a larger intercooler (wanted to do this anyway) with all new piping - done a pressure test with no leaks..

All I can think of is that the 06 models are set up to be rich when the ECU is reset and then lean out as the car is driven. Safety maybe? Use a heap of fuel in the meantime though!

Going to rescale my MAF next. Also got a wide band O2 on the way - interested to see whether OL is really rich or not.

Keep you posted,
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