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Old 09-30-2014, 12:33 AM   #1
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Default First and (sometimes) second pull super lean. No enchriments. NB1.

So I've been having this problem since I started tuning, and I've recently disabled all enrichments to try and solve it. AE, EAE, Overrun, errything.

So here's the scenerio. Drive around until the car is warm, ~190F or so. The FIRST pull I do, it spikes to 14. Often times the second pull, spikes to 14. After that though, max 13.1 and we're sailing smooth. I am all but convinced this has to be a hardware issue of some kind. Possibly fuel pressure related? Anyone have any ideas? Returnless fuel system, NB1. I know DNMakinson had had a similar issue with a returnless system.

Also, AFR safety cuts spark/fuel when this happens, yet when I look at the log the injector PW is still > 0, perfectly in line with where it was before. I am confused by this. You can see the dip circled below where the car obviously had power cut, yet the PW doesn't drop until TPS = 0.

Log and tune attached. Any suggestions as to some possible remedies to fix this issue would be greatly appreciated.


Attached Files
File Type: msq Tune With Weird Lean First Pull.msq (239.7 KB, 55 views)
File Type: msl 2014-09-29_15.21.05 home from school.msl (685.8 KB, 49 views)
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Old 09-30-2014, 08:53 PM   #2
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Another log, 3rd gear this time.
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File Type: msl 2014-09-30_17.27.49 first pull third.msl (266.9 KB, 63 views)
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Old 10-01-2014, 12:09 AM   #3
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1) My issue was only evident at small pulse widths when variable dead time occurs.
2) Not related to your issue... but, turn off Barr Corr (not needed).
3) I would not do any spark cuts (like Rev Limit) on an engine with a CAT. No stories to tell, just doesn't seem like the way to go.
4) EGO is set to Simple, rather than No Correction, but only active over 6500RPM, so that is not it either.
5) On these logs I see transients that last about 0.6 seconds, then a rather steady situation. I see the places where you have the 13+ AFR's but I do not see a comparison log where you see <13 AFR (the ones you like). I've looked at some of your other logs as well, that do have some runs at lower AFR, and cannot see where the fueling is being called for differently enough to account for he difference in AFR.
6) My only hypothesis is non-steady state CAT effects, as your WBO2 is after the pre-cat.

I hate you are still fighting this.
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Old 10-01-2014, 12:22 AM   #4
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Quote:
Originally Posted by DNMakinson View Post
1) My issue was only evident at small pulse widths when variable dead time occurs.
2) Not related to your issue... but, turn off Barr Corr (not needed).
3) I would not do any spark cuts (like Rev Limit) on an engine with a CAT. No stories to tell, just doesn't seem like the way to go.
4) EGO is set to Simple, rather than No Correction, but only active over 6500RPM, so that is not it either.
5) On these logs I see transients that last about 0.6 seconds, then a rather steady situation. I see the places where you have the 13+ AFR's but I do not see a comparison log where you see <13 AFR (the ones you like). I've looked at some of your other logs as well, that do have some runs at lower AFR, and cannot see where the fueling is being called for differently enough to account for he difference in AFR.
6) My only hypothesis is non-steady state CAT effects, as your WBO2 is after the pre-cat.

I hate you are still fighting this.
1) Ah, okay. I'd been busy and hadn't done more than skim the thread. Classes are crazy atm.
2) Will do.
3) Yeahhhhh. Seeing as I have 2 cats, probably would be the smart idea. I had the same warnings when I set it though, really don't have a valid defense for why I chose to do it anyway.
4) On no correction now.
5) I've honestly been using AFR Safety as my reference. Car is killed for the first two, all others after are fine. The more pulls i do, the closer to targets it seems to get.
6) That is my only guess as well. Damn California cars. So I think the result might be just putting up with it and trying to behave myself until the exhaust is finished. After that, if the problem still exists, I'll re-approach it.
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