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afr question

Old 31-08-2014, 05:32 PM
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marcgj
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Default afr question

i know there's afew mappers/tuners here so maybe someone could answer this...

right.. my afr with the standard airbox is 13.2 at wot

but with a piperx venom filter its 12.2 at wot

so..by this, does it mean my airbox flows better than the venom?

car inquestion is a mk6 escort with a 2.3 engine running rs2k ecu (no chip)

(have megasquirt to fit in the future)

thanks.
Old 31-08-2014, 05:47 PM
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tony66
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Default afr

on the surface it would appear so
does it run closed loop for normal running? something could be happening there
but its a fair bit of difference
Old 31-08-2014, 07:05 PM
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Originally Posted by tony66
on the surface it would appear so
does it run closed loop for normal running? something could be happening there
but its a fair bit of difference
its on the standard ford rs2000 ecu,so im not sure tbh im not very clued up on this area,but at cruise im 15-15.5 which ive read is normal and fine.

basically i fitted the viper thinking as its enclosed and a cone it would provide more air but looking at my afr it doesn't look that way,if i find out the airbox is better it'll be going straight back on no doubt.
Old 31-08-2014, 07:22 PM
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Default viper

if that is the case i would send it back if you bought it new-good results can be had on many cars with drilled/modded standard airboxes with decent induction pipework feeding them cold air...sometimes the cone type filters just take in hot underbonnet air
Old 31-08-2014, 07:35 PM
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as its and enclosed filter with a cold air feed it doesn't suffer from heat soak.

standard airbox is fitted with a k@n panel and has a second air feed added.

viper was a ebay bargain,so wont lose money selling.

thanks for your input.

Last edited by marcgj; 31-08-2014 at 07:37 PM.
Old 05-09-2014, 09:11 PM
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stevieturbo
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Originally Posted by marcgj
i know there's afew mappers/tuners here so maybe someone could answer this...

right.. my afr with the standard airbox is 13.2 at wot

but with a piperx venom filter its 12.2 at wot

so..by this, does it mean my airbox flows better than the venom?

car inquestion is a mk6 escort with a 2.3 engine running rs2k ecu (no chip)

(have megasquirt to fit in the future)

thanks.
Is there an air temp sensor somewhere ? Is there an airflow meter ?
Old 05-09-2014, 09:15 PM
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JoshXR2
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the viper is flowing more air and therefore the ecu is injecting more fuel. you wanna be seeing afrs around 12 at wot as an NA car makes peak power around 12.8 stick with the viper
Old 06-09-2014, 07:59 AM
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Originally Posted by stevieturbo
Is there an air temp sensor somewhere ? Is there an airflow meter ?
yes mate there's a sensor at the back of the plenum, and its running a map sensor.

Originally Posted by JoshXR2
the viper is flowing more air and therefore the ecu is injecting more fuel. you wanna be seeing afrs around 12 at wot as an NA car makes peak power around 12.8 stick with the viper
ok mate,so do you know what a factory tuned na cars afr woul be roughly?
Old 06-09-2014, 08:20 AM
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In that case if a change in air temp hasnt caused the change in mixture, the Viper is flowing less air causing it to be richer.

The engine has no way of knowing actual airflow without an airflow meter.

Typically a n/a you'd want to be around 12.8-13 or so.

12.2 is very very rich

the Viper is not helping you.
Old 07-09-2014, 09:44 AM
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Originally Posted by stevieturbo
In that case if a change in air temp hasnt caused the change in mixture, the Viper is flowing less air causing it to be richer.

The engine has no way of knowing actual airflow without an airflow meter.

Typically a n/a you'd want to be around 12.8-13 or so.

12.2 is very very rich

the Viper is not helping you.
ok mate,thanks.

that was my understanding,ny way was as its running at 13.2 with the standard airbox the ecu cant supply enough fuel for it to match the air its taking in,but with the viper its taking in less air so it can supply enough fuel for that.
Old 07-09-2014, 10:06 AM
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With the standard airbox etc it is supplying enough fuel, 13.2 is fine.

The difference may be air temp related, you'd need to monitor air temps with both to see though.
Sometimes induction kits end up sucking hot air, whereas OEM airboxes are ducted externally so always get colder air.

But people often give OEM airboxes less credit than they deserve
Old 07-09-2014, 02:52 PM
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Originally Posted by stevieturbo
With the standard airbox etc it is supplying enough fuel, 13.2 is fine.

The difference may be air temp related, you'd need to monitor air temps with both to see though.
Sometimes induction kits end up sucking hot air, whereas OEM airboxes are ducted externally so always get colder air.

But people often give OEM airboxes less credit than they deserve
ok steve,thanks for your advice,think i'll put the standard airbox back on for now.

but it will be getting mapped next year so i'll ask him to try both.

thanks.

marc.

thanks.

marc.
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