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Old 01-02-2008, 09:35 AM   #1
Rogan
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Default 10:1 AFRs on boost transition - Enginuity

I've been discussing my tuning issues with a couple of you Enginuity gurus, via email, concerning my issue I'm having enormous trouble resolving.. I thought I'd post this to the forum, in case someone has dealt with this scenerio in the past, or in case someone else runs into this issue..

Here's the parts list:

EJ25 block/crank
Arias 9.5:1 pistons
Eagle H-Beam cromoly rods
ARP head-studs and rod-bolts
Cometic Head Gaskets
TGV deletes
Modified stock Injectors (~830cc, decapped)
Precision GT32/55 turbo (48lb/min)
Rotated uppipe
Tial 46mm Ext. Wastegate 1.1bar spring
Tial 50mm BOV
Precision FMIC
2.5” hot-side FMIC piping
3” cold-side FMIC piping
3” intake (MAF in 3” pipe)
Aeromotive fuel rails
3/8” fuel lines
STI FPR
Stock cams
3 angle valves, blended bowls
AR Fab modded oil pump (190*F, 70psi idle, 100psi @ off-idle)
Walbro 255lph, 42psi idle


When cold, it starts right up, idles fine. As it warms up and idle starts to drop, if begins to get rougher and rougher.. It seems to drive "ok" through town, with a slight miss here/there.. BUT, when accelerating, and the transition from vacuum to positive pressure takes place, the car goes full-RICH, instantly.. Logs of both the WBO2 and the AF Sensor #1 confirm this. I'll add that when this occurs, the car stumbles a good bit, obviously due to the huge amount of fuel, I'd assume.

Cruising around town, steady 30-40mph, it reads 14.8-15.3 AFRs..

Ive rescaled my modded stock injectors from 835 to 725, and multiplied the tip-in throttle enrichment table by .58 (420/725). It acted the same, when scaled to 835.
Ive got no idea what I need to do to correct this issue..
Any ideas?

I’ve got a log from yesterday. In the attached snippet of the log, you can see an area where the AFRs go to 11 or richer.. I’m not really flogging the car, but more of just like 2nd gear, throttle boosted acceleration.



the "wbo2" column is calculated from 0-5V input to ecu 'fuel level (V)' from my PLX wbo2 0-5V output, converted to AFR by =SUM(H2*2+9) equation. You can see from the log, that it's about a point or so, off of the AF Sensor #1 AFR reading.. Although, it is about 4' downstream of Sensor#1.
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Last edited by Rogan; 01-02-2008 at 09:44 AM.
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Old 01-03-2008, 08:11 AM   #2
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Well, at first glance I think you have your injectors scaled too small as the A/F correction is very negative, denoting too much fuel.

I would spend more time getting the injectors properly sized and the latencies correct. Have you adjusted the latencies yet?

Just a quick guess but your injectors should end up around 750-780 and the latencies need to be increased 30-40% or so. (I am assuming that these are modded WRX injectors as I seem to remember that you have a WRX). I tuned a set of modded injectors on an 03 WRX a while ago and they did take some time to get right.

You should also log your A/F Learning A-D over time. These all should be around +/-5% long term. If not then you need to tune the injectors more.

Also, how did you tune the new MAF pipe? Are you trying to tune both the injectors and the MAF at the same time? If so, it will be much more difficult.

PM me if you need more info or want to chat.
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Old 01-03-2008, 08:46 AM   #3
Rogan
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Thanks for the posting..
Last night, I rescaled the injectors to 750, and that was the only change.. Here's a screenshot of the log snippet, where boost transition occurred.. In addition, the car will not idle on it's own, with the injectors scaled from 725 to the new 750.

They are, indeed, modded stocker WRX injectors.

I haven't tuned the MAF pipe yet, either. Unfortunately, I am trying to tune the two, together, which as you said, has proved to be quite difficult: especially given the fact that I, too, am on a tuning learning curve with this! lol


Last edited by Rogan; 01-03-2008 at 12:23 PM.
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Old 01-03-2008, 10:55 AM   #4
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Tuning larger injectors and a big maf at the same time is a pain. Just find the scalar/latency values that make your idle good and scale the maf from there. Please note that changing your MAF scaling will cause your engine load to move around so watch out for that. You don't want to move into a low load column with a lot of timing in it at high boost. You are running very little timing at 15psi and very rich too. I run 11.1:1 and 16-17* at 4500rpm and 22psi.
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Old 01-03-2008, 11:27 AM   #5
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Quote:
Originally Posted by bchslap View Post
the "wbo2" column is calculated from 0-5V input to ecu 'fuel level (V)' from my PLX wbo2 0-5V output, converted to AFR by =SUM(H2*2+9) equation. You can see from the log, that it's about a point or so, off of the AF Sensor #1 AFR reading.. Although, it is about 4' downstream of Sensor#1.
According to http://www.plxdevices.com/M-Series-C...utputGraph.jpg, your conversion from voltage to AFR is incorrect and produces AFRs that are one point richer than the actual AFRs
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Old 01-03-2008, 11:33 AM   #6
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here's a snapshot of the ign table... looking at log, where my AFRs go from 11s to 9s, and matching that area to the IGN table, I see that timing is greatly reduced there..

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Old 01-03-2008, 11:42 AM   #7
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Quote:
Originally Posted by Jon [in CT] View Post
According to http://www.plxdevices.com/M-Series-C...utputGraph.jpg, your conversion from voltage to AFR is incorrect and produces AFRs that are one point richer than the actual AFRs
thanks, jon. I initially started out using "10" (I think about a year ago, you helped me with the conversion, initially, on enginuity forum.. ), then somewhere down the line, I got messed up and used "9". I'll redo the conversion. It's still extremely rich
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Old 01-03-2008, 11:52 AM   #8
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Watch out having too little timing. It'll make your egt's go up.
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Old 01-03-2008, 12:15 PM   #9
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yeah, i noticed the EGTs high, last night.. well, relatively speaking.. sitting in the driveway, holding throttle to 2500, the EGTs went to 1350. probe is 4" from the head, on #4 cyl.
Idle sits around 8-900F, which is higher than I'm used to seeing..
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Old 01-03-2008, 12:25 PM   #10
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post #3 is updates screenshot with wbo2 calcs corrected to "10", nstead of the incorrect "9"..
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Old 01-03-2008, 12:36 PM   #11
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Quote:
Originally Posted by bchslap View Post
here's a snapshot of the ign table... looking at log, where my AFRs go from 11s to 9s, and matching that area to the IGN table, I see that timing is greatly reduced there..

weirdest looking base timing I have ever seen - what is the advance table like - you must have some huge values in there?
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Old 01-03-2008, 01:53 PM   #12
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looks to me like he's using 10* of advance throughout the entire timing map.
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Old 01-03-2008, 03:38 PM   #13
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Let me start by saying I'm a noob when it comes to this stuff...perhaps your throttle tip in needs tweeking. in both cases, you are going almost 100+% increase in throttle quickly and then the car goes rich. log the tip in % and "last calcualted enrichment"(or something like that). you may want to decrease the tip in and see if that helps. However, I would imagine that as you start to get your injectors and MAF set correctly, you may also need to keep adjusting the tip in....so like it was said before(maybe another thread), put your factory air box on first...get it settled, and then switch.
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Old 01-03-2008, 04:00 PM   #14
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Quote:
Originally Posted by benw View Post
looks to me like he's using 10* of advance throughout the entire timing map.
the entire Timing Advance (Maximum) table is 9.4

Quote:
Originally Posted by Wheeler Bement View Post
Let me start by saying I'm a noob when it comes to this stuff...perhaps your throttle tip in needs tweeking. in both cases, you are going almost 100+% increase in throttle quickly and then the car goes rich. log the tip in % and "last calcualted enrichment"(or something like that). you may want to decrease the tip in and see if that helps. However, I would imagine that as you start to get your injectors and MAF set correctly, you may also need to keep adjusting the tip in....so like it was said before(maybe another thread), put your factory air box on first...get it settled, and then switch.
The tip-in has been multiplied by .56, already, but that doesn't make it right, I know

As for the factory airbox:



Not really an option
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Old 01-03-2008, 04:27 PM   #15
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Quote:
Originally Posted by bchslap View Post
As for the factory airbox:
Not really an option
nice setup, since the box is not an option...good luck.

as for the tip in table, start pulling it back

I may be wrong here, and just my opinion, but hopefully, your MAF behavior will be consistent. if so, I would leave it alone and just tune around it. think about it, load is based on RPM and MAF...so as long as both are consistent(right or wrong) the map should reflect it, perhaps in "lumpy" timing and a very lumpy fuel table....but that will then show where the focus needs to be.
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Old 01-04-2008, 01:51 AM   #16
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I've heard of this happening on FMIC cars where the stock MAF placement is retained, but I would think that behavior would not be found on a blow-through setup. I'm eagerly awaiting some expert comments on this one, as I'm in the same boat, albeit with a stock MAF location.
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Old 01-04-2008, 09:57 AM   #17
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Ben,
My maf is geograhpically in the OE location, give or take an inch.. It's not blow-through, either. I was going to go blow-thru, but heard it's a bunch of headache to tune.. look at me now, go figure! lol
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Old 01-04-2008, 11:41 AM   #18
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If it's continously rich during open loop fueling then it's a Fuel injector scale issue. If it's just a spike that returns to normal then it's the problem a bunch of us have been dealing with.
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Old 01-04-2008, 01:22 PM   #19
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Hmm, I don't have my tuning laptop with me, but I recall a map in street tuner that was like tip in enrichment, except for changes in manifold pressure as opposed to changes in tps. Cobb calls it fuel injector boost error trim, i'm not sure what enginuity calls this table, but its worth looking into.

Found this little gem, which should apply to you with the stock location maf. More here: http://www.cobbforums.com/forums/ima...ubarusv111.pdf
Quote:
IF YOU ARE RUNNING WITH A FRONT MOUNT INTERCOOLER, WE SUGGEST YOU SET ALL OF THESE VALUES TO ZERO (see below
table). This will help prevent over-fueling the engine due to the time delays associated with having the MAF sensor located further away from the throttle
body. With a front-mount intercooler installed, you have dramatically increased the length of intercooler piping. The MAF sensor meters the additional air
coming into the engine before the air actually reaches the engine. This can create a temporary over-fueling of the engine until the increased air charge
reaches the engine.
*edit: enginuity calls it Throttle Enrichment Compensation (Boost Error).

Good luck
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Old 01-04-2008, 01:45 PM   #20
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thanks for the interesting link and info!
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Old 01-04-2008, 01:50 PM   #21
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Cobb's description of FIBET is incorrect.

It is not based upon rate of change of boost.

It is a multiplier against tip-in based upon boost-error. That's what merchgod said based upon his review of the rom logic. I believe he has it in the defs "help" description as well.
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Old 01-04-2008, 02:52 PM   #22
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Much better logs posted here than the ones you sent me. The fuel table is doing exactly what its told to do. You need to raise the injector scalar to 785-800 & increase the latency to get the idle under control. You are only ~1.0 AFR off from what the fuel table is calling for @ >2.0 load. The fuel log vs. Load log is pretty smooth considering the setup isn't dialed in.
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Old 01-04-2008, 03:37 PM   #23
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Quote:
Originally Posted by testes1010 View Post
Much better logs posted here than the ones you sent me. The fuel table is doing exactly what its told to do. You need to raise the injector scalar to 785-800 & increase the latency to get the idle under control. You are only ~1.0 AFR off from what the fuel table is calling for @ >2.0 load. The fuel log vs. Load log is pretty smooth considering the setup isn't dialed in.
thanks, jeremy. Actually, post #3 log snippet is from one of them I sent you on Wednesday ( enginuitylog_20080102_175043.csv)

you've definitely been a big help with this. I wasn't doing any name-dropping, as I didn't know if you'd get bombarded with messages/emails from a bunch of people wanting help, and I didn't wanna be the root of the reasoning
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Old 01-04-2008, 04:03 PM   #24
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Quote:
Originally Posted by mickeyd2005 View Post
Cobb's description of FIBET is incorrect.

It is not based upon rate of change of boost.

It is a multiplier against tip-in based upon boost-error. That's what merchgod said based upon his review of the rom logic. I believe he has it in the defs "help" description as well.
This doesn't come as a surprise, I honestly think cobb doesn't know its own ass from a hole in the ground. Heck, their name 'fuel injector boost error trim' itself points toward merchgod's definition.
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Old 01-04-2008, 05:11 PM   #25
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Quote:
Originally Posted by bchslap View Post
thanks, jeremy.
no problem.....you are not as far off as you think.

#3 post log using AFR table for 'Target AFR'


Depending on what the scalar was for that log, you need to raise the scalar ~10cc per every .1-.2 AFR off (you're roughly .4 off) from target then dial in the latencies & the MAF table for idle.
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