# AFR target under boost?



## the4ork (Mar 10, 2003)

im running solid between 12.5 and 13 a/f ratio on the wideband... only pusing 10lbs now but will be seing 20lbs as soon as i finish my air/water setup...
just wondering if i should richen it up... talked to some guys at a car show today (got 3rd place btw http://****************.com/smile/emthup.gif ) and they say my target AFR for 9:1-9.5:1 should be around 10.5-11 @ 20psi and nothing above 12 @ 10psi...
they also said i should make more power and it will lower my egt's as well, and i should be able to run a few more deg of timing... currently running about 18-20deg @ 10psi


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## mirror (Dec 18, 2006)

*Re: AFR target under boost? (the4ork)*

you tune for power. watch your egt's, and run it as lean as you can while keeping egts safe, and no detonation. lower timing+leaner a/f=higher egts. higher timing+richer a/f=lower egts. higher timing+leaner a/f=detonation city. throw it on a dyno, and tune the curve for power, and if you start detonating, add a little fuel. 


_Modified by mirror at 6:45 PM 9-29-2007_


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## Stroked1.8t (Jan 9, 2004)

*Re: AFR target under boost? (mirror)*

nothing above 11.8 at any psi while wot


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## ValveCoverGasket (Mar 20, 2002)

*Re: AFR target under boost? (the4ork)*


_Quote, originally posted by *the4ork* »_they also said i should make more power 

peak torque is at 13.5 if i remember right...probably will start to heat things up too much there though


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## IwannaGTI (Jul 12, 2001)

*Re: AFR target under boost? (ValveCoverGasket)*

im at 13.5-14.5 on my vrt...








running to the dyno soon to see if my a/f gauge is wrong/bad


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (IwannaGTI)*

right now i'm at 12:1 at 13 PSI on my 2.0t. timing is at 24 advanced most of my way through the rev range in boost. i need to advance it a little more at the top becuase it starts to slow down as i go past 6200 RPM.

EDIT: not detonation. someone abave explained the AFR rule pretty good. more timing=more fuel, less timing=less fuel, but more timing+less fuel= pistons ending up in your engine bay.

_Modified by Flipdriver80 at 3:13 PM 10-1-2007_


_Modified by Flipdriver80 at 3:18 PM 10-1-2007_


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## Stroked1.8t (Jan 9, 2004)

*Re: AFR target under boost? (IwannaGTI)*

you guys talking about ~13.5 while in boost?


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## ValveCoverGasket (Mar 20, 2002)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_right now i'm at 12:1 at 13 PSI on my 2.0t. timing is at 24 advanced most of my way through the rev range in boost.

how much boost are you running on 24* of advance


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (Stroked1.8t)*

13 psi.. if i retard the timing anymore it sounds like the spark is after the piston hits the top of its stroke. car falls on its face. 


_Modified by Flipdriver80 at 3:16 PM 10-1-2007_


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## VWralley (Mar 30, 2002)

*Re: AFR target under boost? (Flipdriver80)*

target a/f ratio for boost is anywhere between 12.5:1 and 13.5:1. anything in there will be fine. I read not too long ago in Grassroots Motorsports that they tested this theory and noticed no gains in leaning out or going richer than that








flipdriver...are you 10000% sure all your base settings and timing is correct? 24 sounds a bit high, but the fact that if you retard it any sounds like what you say, thats not good. you should only notice a slight drop in power when dropping the timing down...something doest sound right to me


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## ValveCoverGasket (Mar 20, 2002)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_13 psi.. if i retard the timing anymore it sounds like the spark is after the piston hits the top of its stroke. car falls on its face. 


sounds like you need to double/triple check your settings, somethings not right there


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (VWralley)*

i know dude i kinda don't get it either given the spark table you are running (VCG). i have the intial advance correct because i've checked it and redone it 2 times. i am at -10 advanced at idle. when i get home i'll take a screen shot of my advance table and you can tell me what you think. i've been driving the car daily and romping on it. just drove it 500 miles round trip to h2o with no problems whatsoever. i'll PM you when i get the screen shot up. http://****************.com/smile/emthup.gif


_Modified by Flipdriver80 at 3:44 PM 10-1-2007_


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## VWralley (Mar 30, 2002)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_ i am at -10 advanced at idle. 
_Modified by Flipdriver80 at 3:44 PM 10-1-2007_

this is a big red flag to me. you should def be a bit higher that -10 at idle! all the cars i have done sit at 6-10 degrees adv.
are you sure you set the base timing correctly?
1. set fixed angle (i hope thats right) to 6- burn to ecu
2. set engine timing light to zero and rotate until it lines up with the bellhousing on the big dash on the flywheel (6* btdc)
3. lock down dizzy
4. set fixed back to -10 - burn to ecu


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (VWralley)*

yeah 10 degrees advanced... not retarded 10 degrees. i wrote it wrong sorry


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## VWralley (Mar 30, 2002)

*Re: AFR target under boost? (Flipdriver80)*

are you running an MSD or similar additional spark box by chance?


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## mirror (Dec 18, 2006)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_yeah 10 degrees advanced... not retarded 10 degrees. i wrote it wrong sorry


did you verify your timing via a timing light? you need to correct the table or dizzy if it's off. 
ie: timing light shows 8* btdc, but table shows 10* btdc.


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (mirror)*

no aftermarket spark here.
ok this is what i did just so everyone knows:
set MS to 6 degrees advanced
use timing light and adjusted distributor to 6 degrees advanced on the flywheel mark
tighten down distributor and change MS to 10 degrees
then burn to ECU, just like it says on patatrons site, i followed the directions word for word.


_Modified by Flipdriver80 at 4:31 PM 10-1-2007_


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## mirror (Dec 18, 2006)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_no aftermarket spark here.
ok this is what i did just so everyone knows:
set MS to 6 degrees advanced
use timing light and adjusted distributor to 6 degrees advanced on the flywheel mark
tighten down distributor and change MS to 10 degrees
then burn to ECU, just like it says on patatrons site, i followed the directions word for word.

_Modified by Flipdriver80 at 4:31 PM 10-1-2007_

did you reverify that the timing light was at 10* though? i know, you're thinking it was dead on at 6*, why would it not be dead on at 10*...i would re-verify that. 24* and it feels like it's falling on it's face points to your timing being off, spark being blown out, or fuel being off.


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## VWralley (Mar 30, 2002)

*Re: AFR target under boost? (Flipdriver80)*

you set the MS setting to 6 before you changed the timing in the motor correct? (you didnt state this, just clarifying as its very important for the process)


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (mirror)*

yes i set the MS to 6 before i rotated the distributor.
no its at 24 now and running great http://****************.com/smile/emthup.gif
when i lower it to around 18-20 it gets slower
my timing light does not have an adjustment on it. i'm using the 6* tming mark on the flywheel.

when i get home in a half hour i'll post it up.


_Modified by Flipdriver80 at 4:39 PM 10-1-2007_


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## mirror (Dec 18, 2006)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_yes i set the MS to 6 before i rotated the distributor.
no its at 24 now and running great http://****************.com/smile/emthup.gif
when i lower it to around 18-20 it gets slower
my timing light does not have an adjustment on it. i'm using the 6* tming mark on the flywheel.

when i get home in a half hour i'll post it up.

_Modified by Flipdriver80 at 4:39 PM 10-1-2007_

o hell man, you're fine. http://****************.com/smile/emthup.gif


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (mirror)*


_Quote, originally posted by *mirror* »_
o hell man, you're fine. http://****************.com/smile/emthup.gif 

fine with what? i just checked. at high boost 13psi i'm at 25*

i know its high towards the bottom right, i need to reduce it a little but i never see that advance unless i'm off the throttle. i have been debating on increasing the advance as it increases in RPM past 6200 because it kinda dies after that point.


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## ValveCoverGasket (Mar 20, 2002)

*Re: AFR target under boost? (Flipdriver80)*

something doesnt look right there unless youre on some magic gas...
but your idle looks reasonable...so...
what does your spark settings window look like?


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## VWralley (Mar 30, 2002)

*Re: AFR target under boost? (Flipdriver80)*

one thing i could suggest is spreading out your lower bin values to have a better spread through your normal driving zones 2500-4500 rather than 100 rpm increments at the top (notice its 25 accross anyway). that will allow more tweaking under normal driving for better economy and driveabilty


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (VWralley)*


_Quote, originally posted by *VWralley* »_one thing i could suggest is spreading out your lower bin values to have a better spread through your normal driving zones 2500-4500 rather than 100 rpm increments at the top (notice its 25 accross anyway). that will allow more tweaking under normal driving for better economy and driveabilty









ok cool i'll see.
VCG let me get a pic of my spark settings.


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## Flipdriver80 (Jul 17, 2004)




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## VWralley (Mar 30, 2002)

*Re: AFR target under boost? (Flipdriver80)*

just remember, being limited on bins, the MS will use percentages of the one its on and the next one in a linear fashion, so values across the top would only need one line of bins instead of 4 or 5 like you have...also if you stop a bit higher in the rpm than you run, this will help protect if you over-rev the motor for some reason


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## VWralley (Mar 30, 2002)

*Re: (Flipdriver80)*

i have always used 60 for the trigger angle, thats about all i see, dont know if that would cause the same thing you are seeing...
maybe you are just able to run more timing due to the rod ratio for the ABA







not sure, just seems like a ton of timing to me..


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## ValveCoverGasket (Mar 20, 2002)

*Re: (VWralley)*


_Quote, originally posted by *VWralley* »_maybe you are just able to run more timing due to the rod ratio for the ABA







not sure, just seems like a ton of timing to me..

still seems like a ton
have you run it up to those load points and held it for a significant amount of time? or have you tuned that map by running it into boost quickly without letting things stabilize?


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## Flipdriver80 (Jul 17, 2004)

*Re: (VWralley)*


_Quote, originally posted by *VWralley* »_i have always used 60 for the trigger angle, thats about all i see, dont know if that would cause the same thing you are seeing...
maybe you are just able to run more timing due to the rod ratio for the ABA







not sure, just seems like a ton of timing to me..

i never understood what the trigger angle was, can you please explain that for me. thanks. also i'll check about edjusting the bins thanks.


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## VWralley (Mar 30, 2002)

*Re: (Flipdriver80)*

if i understood it, i would








just going by what i always use, and ive done/timed/help on well over 15 cars...


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## ValveCoverGasket (Mar 20, 2002)

*Re: (VWralley)*


_Quote, originally posted by *VWralley* »_if i understood it, i would










read man!








"Trigger Angle (deg) is the angle Before Top Dead Centre (BTDC) when the selected trigger position (Trig Pos) Tooth (if using wheel decoder) or the Vane on the crank or the Points in a locked distributor, etc, passes the sensor. This is used by the ECU to calculate when to fire the coil(s) as it knows that every time it receives a trigger pulse it is at xxdeg BTDC and the entire spark map is worked out when to fire from the Trigger Angle. "


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## Flipdriver80 (Jul 17, 2004)

*Re: (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_
still seems like a ton
have you run it up to those load points and held it for a significant amount of time? or have you tuned that map by running it into boost quickly without letting things stabilize?

yeah i've taken it up through boost smoothly and held it. especially during highway driving.


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## cabzilla (Jan 3, 2000)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_
fine with what? i just checked. at high boost 13psi i'm at 25*

i know its high towards the bottom right, i need to reduce it a little but i never see that advance unless i'm off the throttle. i have been debating on increasing the advance as it increases in RPM past 6200 because it kinda dies after that point.










There are no compensation tables for your timing map?


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (cabzilla)*

not sure what you mean


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## mirror (Dec 18, 2006)

*Re: AFR target under boost? (Flipdriver80)*

i think he means if your coolant temp gets past xxx it will pull xx timing, same as iats.


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## ValveCoverGasket (Mar 20, 2002)

*Re: AFR target under boost? (mirror)*

has one of those :thumbup
for iat and for coolant


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## need_a_VR6 (May 19, 1999)

*Re: AFR target under boost? (Flipdriver80)*

I would double check the setup, the numbers do look pretty high for pump gas. If the trigger setup is wrong, take the offset out of the table.


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## Flipdriver80 (Jul 17, 2004)

what offset?


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## need_a_VR6 (May 19, 1999)

*Re: (Flipdriver80)*

If your indicated timing and the measured timing don't agree, fix it, and take the same amount (offset) out of your table.


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## Flipdriver80 (Jul 17, 2004)

*Re: (need_a_VR6)*

ok thats what i thought you meant. so in actuality i could be off by 2 points because my trigger angle is 58 when others (VWralley) is using 60. got ya. thanks.


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## MarcoVR6SC (May 3, 2003)

*Re: (Flipdriver80)*

Trigger angle is just the crank sensor offset to TDC, as mentioned.
But as you can turn the distributor, you are adding a second offset to the advance reference (I guess the sensor is in the distributor). So when you checked with a timing light and turned the distributor to have 6° advance, then you're spot on. The only thing to check would be putting a different advance number (try 0) and check again with the timing light if it's on the 0 mark.


_Modified by MarcoVR6SC at 7:48 PM 10-2-2007_


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## Flipdriver80 (Jul 17, 2004)

so in case you guys are still wondering about my car i just checked the timing and it was off on the flywheel a little but. i just re-set the timing at idle and synced it with the megasquirt again. just thought yall might want to know.


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## VWralley (Mar 30, 2002)

*Re: (Flipdriver80)*

any changes in the ignition action in boost?


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## ValveCoverGasket (Mar 20, 2002)

*Re: (VWralley)*

oughta be


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## VWralley (Mar 30, 2002)

*Re: (ValveCoverGasket)*

my roomate an I have been wondering this...if you are say 2* off in your base timing, is it a straigh line as far as being off in the map? like in an upper area with say 30* you would actually be at 32* or would it be more linear and be off by much more?


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## ValveCoverGasket (Mar 20, 2002)

*Re: (VWralley)*

should be 1:1
same as if you set the base timing wrong on anything else. you set 10 degrees and the ecu thinks 6. itll be requesting 30 and actually getting 34. if the distributor doesnt move...


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## mirror (Dec 18, 2006)

*Re: (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_so in case you guys are still wondering about my car i just checked the timing and it was off on the flywheel a little but. i just re-set the timing at idle and synced it with the megasquirt again. just thought yall might want to know.

i figured this would be the issue. how does it run now?

_Quote, originally posted by *ValveCoverGasket* »_should be 1:1
same as if you set the base timing wrong on anything else. you set 10 degrees and the ecu thinks 6. itll be requesting 30 and actually getting 34. if the distributor doesnt move...

bingo. it's not like fueling where your d/c will increase/decrease.


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## Flipdriver80 (Jul 17, 2004)

*Re: (mirror)*

its much more responsive than before and running much better. it was misfiring before and i thought it was the spark plugs. i think the distributor moved somehow. it pulls much harder also. it was off in the timing making it too advanced. was breaking up a little in the top end when it never was doing that.


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## ValveCoverGasket (Mar 20, 2002)

*Re: (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_its much more responsive than before and running much better.

and youre still running 24* of advance at full boost?


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## Flipdriver80 (Jul 17, 2004)

*Re: (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_
and youre still running 24* of advance at full boost?

mhmmm... http://****************.com/smile/emthup.gif 
edt: and i changed the trigger angle to 60 instead of 58 which is what it was at.


_Modified by Flipdriver80 at 7:12 PM 10-3-2007_


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## VWralley (Mar 30, 2002)

*Re: (Flipdriver80)*

thats crazy, i havnt seen that much timing in boost before personally, get that thing on the dyno for some tuning and see what kinda power its putting out http://****************.com/smile/emthup.gif


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## ValveCoverGasket (Mar 20, 2002)

*Re: (VWralley)*

thats insane
definitely get that thing on a dyno!


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## Flipdriver80 (Jul 17, 2004)

*Re: (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_thats insane
definitely get that thing on a dyno!

i've got some dyno numbers for you guys coming up soon. its being dyno'd on the 13th. http://****************.com/smile/emthup.gif i'm going to try to tone down the timing in full boost tomorrow if i have time just to experiment. i want it running really well for when its dyno'd.


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## need_a_VR6 (May 19, 1999)

*Re: (Flipdriver80)*

I would take some timing out at high load until you hit the dyno.


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## GTijoejoe (Oct 6, 2001)

*Re: AFR target under boost? (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_
how much boost are you running on 24* of advance

This is totally going to depend on your compression ratio~ remember if you are going to compare setups and boost
I run ~8.75 CR 20psi @ 24* with a t3/t4 50 trim A/F = 11.8-12 WOT
I personally tune for 12.5 for around 10psi-ish and 11.8-12 for anything above. But always watch your EGT and detonation, that will control how far you can push your limits. 
Also, tuning parameters can and will be totally different for different engines for fine tuning. 
Perhaps Jeff will chim in
fork-
~also make sure your TDC trim is set properly, there is a 0* advance to help you check with a timing light with 034


_Modified by GTijoejoe at 10:59 AM 10-4-2007_


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## Flipdriver80 (Jul 17, 2004)

*Re: AFR target under boost? (GTijoejoe)*

interesting. what are you using to drop your compression? i have a BBM head spacer in my car right now. 2.0t w/ t3/t4 50 trim.


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## ValveCoverGasket (Mar 20, 2002)

*Re: AFR target under boost? (GTijoejoe)*


_Quote, originally posted by *GTijoejoe* »_
fork-
~also make sure your TDC trim is set properly, there is a 0* advance to help you check with a timing light with 034


thats what he did a little bit earlier with locking the spark output to 6* http://****************.com/smile/emthup.gif


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## GTijoejoe (Oct 6, 2001)

*Re: AFR target under boost? (Flipdriver80)*


_Quote, originally posted by *Flipdriver80* »_interesting. what are you using to drop your compression? i have a BBM head spacer in my car right now. 2.0t w/ t3/t4 50 trim.

currently.... 2 stock 5-layer gaskets


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