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Techsalvager
Joined: 21 Jun 2011
Posts: 140
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 Posted: Tue May 08, 2012 6:29 am Post subject: maf tuning |
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Hello once again.
I've come into an issue I'd like to find out information on.
I have my maf placed in front the turbo with a recirculating valve.
My issue is though at certain spool up times, usually low rpm I get oscillating maf signal which starts throwing off the maf fuel calculation obviously.
What is the common ways to figure out what could be the cause of this.
My first guess is intake resosance\pulses durning spool up.
You can see at wot from down low this happen, so it will oscilate the worst down low, then become smooth flat, then oscilate again, repeated.
I will post a picture up of the ADC and what it does under wot from low going to around a bar+ of boost. |
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StantonWarrior
Joined: 10 Dec 2010
Posts: 188
Location: UK
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| Posted: Tue May 08, 2012 6:35 am Post subject: |
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What type of filter do you have, and how close is it to the MAF sensor?
They rely alot on near laminar flow, and mesh type filters which are often fitted directly onto the housing, screw this up and cause turbulent flow. |
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nfn15037
Joined: 22 Dec 2005
Posts: 243
Location: Boston, MA
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| Posted: Tue May 08, 2012 8:44 am Post subject: |
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Compressor surge?
Using a plastic matrix before the MAF to straighten the flow up and smooth things out can help with odd MAF oscillations. I've dealt with some intekt/turbo combos that just did not give a good airflow estimation from the MAF. Generally changing to a blow through or using some sort of flow straighteners will help but no guarantee.
Check out the newer AEM intakes for Subaru and EVOX to see some well designed flow-straighteners. |
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louiswun
Joined: 30 May 2005
Posts: 12
Location: Hong Kong
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| Posted: Tue May 08, 2012 11:59 am Post subject: |
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If there are 2 piping bend between the MAF and the compressor, it will eliminate the turbulent create by the compressor
_________________
Louis A31MT RB20-DET
A Tuning Learner in Hong Kong |
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Techsalvager
Joined: 21 Jun 2011
Posts: 140
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| Posted: Tue May 08, 2012 2:07 pm Post subject: |
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I'm gonna add a few inches on the filter which like statn\on mentioned is currently right on the maf.
Its a nissan n60 maf and has two screens front and back of the unit stock.
I don't think its compressor surge, as the turbo is suited well for the motor and is not overly big. |
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Roberto Arano
Joined: 22 Nov 2005
Posts: 358
Location: colorado
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Techsalvager
Joined: 21 Jun 2011
Posts: 140
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| Posted: Tue May 08, 2012 9:00 pm Post subject: |
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| Roberto Arano wrote: | rpm,MAP,TPS
under what combination (rpm,MAP,TPS) DOES the maf fluctuate and under what combinations does it NOT fluctuate? |
WOT
from atmo to boost it will oscilate then stop a bit later, then start again.
I'll get a log and picture of it posted up, but I plan to throw a straight pipe infront of the maf and see what happens. |
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Roberto Arano
Joined: 22 Nov 2005
Posts: 358
Location: colorado
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Techsalvager
Joined: 21 Jun 2011
Posts: 140
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Guilt-Toy
Joined: 07 Oct 2008
Posts: 87
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| Posted: Tue May 29, 2012 8:33 am Post subject: |
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| if you block off the bov does the issue go away? |
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