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Old 02 February 2014, 07:13 PM
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markb5888
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Default air fuel ratio question

had car on rolling road and the a.f.r was at 10 on chart he said this is rich. i have researched and alot of people saying they run rich from factory?? is this correct.. will i get bore wash from this afr ??
Old 02 February 2014, 07:23 PM
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You normally get mid to high 10`s on full boost but on idle and cruise you should be mid 14`s
Old 02 February 2014, 07:47 PM
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RS_Matt
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Aye Turbo'd motors need to run rich on boost as fuel has cooling properties.
Old 02 February 2014, 08:10 PM
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cheers for quick replys chaps. he said it was perfect on idle a cruising. but drop to 10 on WOT. So is this ok or will i get bore wash or other problems??? there is no black smoke or anything on boost. and car runs perfect?
Old 02 February 2014, 08:29 PM
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Has it been remapped or is it still on the factory map do you know, It might be worth asking one of the mappers their opinion, Simon@JGM or Duncan@Racedynamix
Old 02 February 2014, 08:39 PM
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it has the ppp kit fitted and a decat upipe. i have read that the ppp map does run rich??
Old 02 February 2014, 09:35 PM
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RS_Matt
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Originally Posted by markb5888
cheers for quick replys chaps. he said it was perfect on idle a cruising. but drop to 10 on WOT. So is this ok or will i get bore wash or other problems??? there is no black smoke or anything on boost. and car runs perfect?
I've suffered borewash, the only indicator it was happening was that the car started to judder at the traffic lights. This is the later stages of borewashing when the piston rings start crumbling and compression isn't spread evenly.

I took it to a very respected tuner and he test drove the car and he felt it was running sweet so I'd deffo get the car checked for boost leaks etc.
Old 02 February 2014, 10:32 PM
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Originally Posted by RS_Matt
I've suffered borewash, the only indicator it was happening was that the car started to judder at the traffic lights. This is the later stages of borewashing when the piston rings start crumbling and compression isn't spread evenly.
well that does not sound good!! i am not getting any running issues. car runs drives perfect and power seems smooth and good?

am i worrying to much? is 10.afr @WOT ok for imprezas
Old 02 February 2014, 10:46 PM
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10 afr a WOT is perfectly safe and normal mine is running at 9.5 but i run a really rich afr as that is how i have tuned it to be
Old 02 February 2014, 10:54 PM
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If one injector or spark plug starts to fail will it reflect noticeably on a wideband AFR sensor?
Old 02 February 2014, 11:25 PM
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Originally Posted by iNeoTom
10 afr a WOT is perfectly safe and normal mine is running at 9.5 but i run a really rich afr as that is how i have tuned it to be
ok thanks for this feel alot happier now
Old 03 February 2014, 10:16 AM
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so does anybody know at what AFR does bore wash start to happen?? or would you notice black smoke or poor running first?
Old 03 February 2014, 10:39 AM
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Hi there

I wouldn't run on my car low 10's AFR like on V-Power or 20% meth,you should have around 11's AFR on yours,I would get car check or get mapped/tweaked if its possible

Jura
Old 03 February 2014, 11:50 AM
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Originally Posted by jura11
Hi there

I wouldn't run on my car low 10's AFR like on V-Power or 20% meth,you should have around 11's AFR on yours,I would get car check or get mapped/tweaked if its possible

Jura
ok why is this too low?? ineotom says its ok he runs 9.5... confussed???

so could i just increase boost ever so slightly. say 1-2psi?? would this lean it out a little?
Old 03 February 2014, 02:14 PM
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Originally Posted by markb5888
ok why is this too low?? ineotom says its ok he runs 9.5... confussed???

so could i just increase boost ever so slightly. say 1-2psi?? would this lean it out a little?
Usually on full boost you need to target high 10's AFR or middle 11's AFR this depends on fuel used and on knock

9.5 AFR is too rich and I wouldn't run that car,yes but off the boost,until car is mapped

Please have look on this

http://www.enginemapper.co.uk/Engine...Guide_V1.1.pdf

Do you trying map yourself yours car ?

If yes do you using det cans and Wideband gauge ?

Jura
Old 03 February 2014, 06:57 PM
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low tens are fine, thats how subaru mapped them on wot. your worrying the chap unnecessary. the car will be in closed loop most of the time and theres plenty other target afrs between maximum load&revs. Far better being rich than lean.
Old 04 February 2014, 02:53 PM
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cheers euan. i cant be running that rich as my car runs fine, it does'nt splutter or anythink on boost. and i get no smoke whatsoever on tickover or on boost. and i cannot smell fuel. :-)

Last edited by markb5888; 04 February 2014 at 02:54 PM.
Old 04 February 2014, 03:16 PM
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Alan Jeffery
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The trick about mapping is to get it right everywhere. It's about the numbers in the boxes. An AFR of 10 won't hurt at full throttle, but the car will perform better on 11.
In conclusion, probably nothing wrong with it, but could do better!
Old 04 February 2014, 04:03 PM
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PPP map is said to be a bit on the rich side to prolong engine life apparently, mine is on 102000 so they must have got something right at that dodgy Prodrive tuning company.
Old 04 February 2014, 10:28 PM
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alan jeffery and ditchmyster thanks for the replys. just what i wanted to hear. thankyou :-)
Old 05 February 2014, 08:53 AM
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I've replied in your other thread. I mapped mine with ESL, the base map for my 97 classic is rich from the factory. I was getting good AFR even before I mapped it. I'd say 2psi more boost will be ok.
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