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Just another misfire/rough idle thread...


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A few weeks ago, I got a P0302 Cylinder #2 misfire code. The misfire only ever happens at idle. I checked the spark plug which looked pretty good. I swapped coils with cylinder #1. Still got the code at idle after I cleared it. Then, I swapped the fuel injector with cylinder #4. The misfire followed (P0304).

 

So, I removed all the injectors, labeled them, and sent them off to be serviced. The tech told me that there were no problems with the injectors ("they all are flowing fine..."). I re-installed the injectors in the same locations, but today I got a P0304--the same location they were installed before I sent them off. Is it possible that the injector is bad and they missed it during testing? Seems like an obvious answer, but has anyone ever had this happen to them? I used these guys: http://accurateis.com/store/index.php

Those guys look competent and I'd really doubt any professional injector service would overlook something bad enough to cause you problems. Did they tell you the flow rate (cc/min) for each of your injectors?

 

Maybe the electrical connections on your problematic injector are slightly bent, just enough to cause problems. That's the best I can come up with.

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Those guys look competent and I'd really doubt any professional injector service would overlook something bad enough to cause you problems. Did they tell you the flow rate (cc/min) for each of your injectors?

 

Maybe the electrical connections on your problematic injector are slightly bent, just enough to cause problems. That's the best I can come up with.

 

I'll have to give them a call, but I vaguely remember them saying 500. But, that could mean anything considering 500cc itself would be low. I know there's an older misfire-related thread on this forum that I've read front to back (~43 pages), but I couldn't find an instance of anyone having their injectors cleaned only to find that the injector was bad. I'll pull it today, check the connection, and swap one more time. Thanks for your input.

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I'm rooting for you Stkmlts. I've had very similar misfire issues for years. You guys are taking the trouble shooting to a whole new level. I blame myself for the issues, as my lgt is extremely modified. I will say my tuner recommended a new ecu. I wasn't willing to spend that much money on a fix that might not work. Hoping you figure it out. I've had my lgt for nearly 12 years (one owner) and I'm not ready to let go of it yet. Good luck!
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Yes. So I used all idle (cold and warm) values from a jdm ecu map to improve my idle.

 

 

 

Curious, since most JDM models are EJ20 models. Which ROM?

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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I'll have to give them a call, but I vaguely remember them saying 500. But, that could mean anything considering 500cc itself would be low. I know there's an older misfire-related thread on this forum that I've read front to back (~43 pages), but I couldn't find an instance of anyone having their injectors cleaned only to find that the injector was bad. I'll pull it today, check the connection, and swap one more time. Thanks for your input.

 

Quoting myself for an update. I pulled #2 and #4 injectors and tested with a multimeter. #4 sits at 12.5 ohms and #2 measured around 12.0. I'm not sure what the tolerances are supposed to be, but it seems that 12.5 might be a bit out of range. I switched them on install and, sure enough, started detecting misfires on cylinder 2 (using btssm). Gotta head to Hueberger for a new injector.

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Curious, since most JDM models are EJ20 models. Which ROM?

You're right. It was for a vehicle with an ej20x/y. However the injectors are the same sidefeed injectors for our 05-06 LGTs in the specific rom I found and used. It may be from an ADM Liberty.

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Since my last update I've adjusted the AFR in the 900rpm row a couple of times and it doesn't look like it's helped (see chart #4).

 

As long as America doesn't implode after today's elections I'm going to bring the 900rpm row back down to -1 (that was AFR test #3, for AFR test #4 I have the values set at -2), and I'm going to change the adjusted values in the 800rpm row up to -1.5. The amount of fuel I'm "wasting" on this experiment doesn't bother me, but I'd rather not dump a ton of fuel into the motor if I don't have to.

 

So....

Adding fuel obviously helped. Whenever I come to a stop I'm still cringing at the inevitable misses, but they're pleasantly softer and almost ignore-able. Should I continue this experiment and take away fuel (higher AFR than stock) to see if the misses get worse? Lean is bad and usually undesirable, but assuming the motor doesn't knock, my logic is telling me that 20 seconds of idling at 15.7 AFR and 0.4 load wouldn't do any permanent damage.

BtSsm_20161108_064405_post4.thumb.png.3690e1a1bf8ad5f1fe9e72e563b0a89e.png

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That was a bad idea. I had my laptop with me today so I reflashed the AFR-rev5 changes while I was in the parking lot before my commute home... during rush hour, in the dark, in the rain. My idle was total crap and stalling was out of control. Creaping forward at <10 mph was all but impossible without bouncing up and down looking like one of those $0.25 ride-a-pony rides in front of an old K-mart. All of thay garbage is pretty usual stuff that I expect to see after a reflash, I just shouldn't have reflashed right before entering stop and go traffic.

 

Sent from inner space.

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I should have done that but I didn't think to.

 

What do you guys think I should be learning from this little experiment? I'm leaning towards focusing my efforts on finding a fueling problem.

 

---Adding fuel at idle improves the misfires.

---My gas mileage is consistent with what I've seen since owning the car, but 18.5 mpg seems to be lower than many other people see in their mostly-stock LGTs.

 

Possibly related (and certainly needs addressed):

---Sometimes I notice a fuel smell outside of the car, and when the tank is 100% full a small amount of fuel (50ml*) leaks out overnight and creates a small wet spot on the ground in front of the rear wheel.

 

*fluid leakage estimate is in metric for birkhoff. -edit- and xt2005bonbon, but only partially because he's in the US and should be using our confusing measuring system.

Edited by StkmltS
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You're right. It was for a vehicle with an ej20x/y. However the injectors are the same sidefeed injectors for our 05-06 LGTs in the specific rom I found and used. It may be from an ADM Liberty.

 

So it needs to be whatever model came with the "14003AB931" TGV's in Japan/ADM? It appears those were used on the ADM FXT at least, and some modesl of the Legacy in Japan.

 

Having a bunch of idel issues that started when the TGV's were changed.

Edited by utc_pyro
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So it needs to be whatever model came with the "14003AB931" TGV's in Japan/ADM? It appears those were used on the ADM FXT at least, and some modesl of the Legacy in Japan.

 

Having a bunch of idel issues that started when the TGV's were changed.

Yes; I just checked last night. I compared two different roms. One was an 06 JDM 2.0 lgt and the second was an 06 ADM liberty. Both have the same injector scalar and latency. I don't have the ecu name with me though.

 

If someone wants, I can list each table I used from the maps. Basically, anything with idle fueling was changed. See the post below to view the tables.

Edited by rhino6303
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Funny, I was just working on an '06 JDM GT that had stumbling / stalling issues. A2UH000A. Yes they do share the same injectors.
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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As promised, here are the tables. The first in each is from a 2005 LGT with A2W522CN ecu. The second is from a 2006 ADM Liberty GT with A2WD010Y ecu and the last is from a 2006 JDM Legacy GT with A2UG000B ecu.

 

For my map, I used all values from the A2UG000B and have no ill effects in about 10K miles. The values from the A2WD010Y seem to be a balance between both.

 

I apologize for the issues with picture quality as I was having trouble getting them cropped and saved correctly.

 

http://legacygt.com/forums/attachment.php?attachmentid=240517&stc=1&d=1478749195

 

http://legacygt.com/forums/attachment.php?attachmentid=240518&stc=1&d=1478749195

 

http://legacygt.com/forums/attachment.php?attachmentid=240519&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240520&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240521&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240522&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240523&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240524&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240525&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240526&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240527&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240528&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240529&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240530&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240531&stc=1&d=1478749555

 

http://legacygt.com/forums/attachment.php?attachmentid=240532&stc=1&d=1478749555

TGV1.png.c10ecf5c977a4217c96be7863f978ae7.png

TGV2.thumb.png.03ca5bab3b2a92e6f31a7a03c26fcc90.png

TGV3.png.58de61d35d42d198d62c9159461fed7c.png

TGV4.thumb.png.dfb7611d2f49686a14d58b263c6e3a9b.png

TGV5.thumb.png.3977e49b37076d850c07f31d9e23cb13.png

TGV6.thumb.png.7e86bd07fd7729d4620392d9735aee3c.png

TGV7.thumb.png.050ff3f483ceff5ab84431357111254e.png

TGV8.thumb.png.2e69e4d8d6897a421aed372740849765.png

TGV9.thumb.png.ba3ee1ecca75e4c9f85cbe7809c51084.png

TGV10.thumb.png.463bcfb1f73157ac82e9240872829ff9.png

TGV11.thumb.png.b72883d8dcabffc61b9ea9b70f32c53c.png

TGV12.thumb.png.75bca3fa980a59d2bc8e2f4e2b10df56.png

TGV13.thumb.png.29f7b3347b889bd3530dad27da37d523.png

TGV14.thumb.png.79bdea32e0c0e8fa125f03bba37cfc1f.png

TGV15.thumb.png.1fceabaf0dfc046a51b301b77d8047b4.png

TGV16.thumb.png.e074f9e46140d6119771dcebbcba9a88.png

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Thanks for taking the time to post those tables.

 

Why did you decide to change your map in the first place?

Was there any noticeable difference after switching to the A2UG000B values?

After installing the jdm tgv deletes my car was always rough at idle (especially at initial start and during warmup). It hunted to stabilize the idle and I saw a lot of a/f correction. There was no vacuum leak and maf scaling was spot on (within 3%).

 

After searching for a while I found the maps associated with foreign models that used sidefeed injectors and saw that everything dealing with idle and startup was different. So i thought I'd give it a shot. My car now runs great at initial start and rarely misfires.

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I'm convinced. I'm leading an orienteering class/course for my scout troop this weekend so it may have to wait until Sunday. I can't imagine it fixing my problem but just the chance of a slight improvement is worth the effort. I'm VERY glad I went opensource vs Cobb.

 

I've also been thinking about turning my boost back up a little sooner than planned :)

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  • 2 weeks later...

I revised my ROM with the A2UG000B tables and flashed it to the car two days ago. I'm sure the new tables are are good thing, but I can't see a difference in the way its idling.

 

For quite a while I've had a small fuel leak near the filler tube. I replace the FP gasket but that didn't help. I've been semi-ignoring the problem, assuming it's a minor-but-dangerous issue, but maybe it's the root cause of my misfires. Adjusting my target AFR @ idle definitely improved my idle, which sounds like it could be evidence to support a fuel deliver problem.

 

For my next reflash I'm going to change the target AFR back to stock, and change the fuel pump duty cycle to always be at 100%... if I can remember where I saw the 2d table in the ROM.

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