Datalog Fueling woes and Cyl5 songs

ShocknAwe

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Jan 24, 2018
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Would love the community input here, I've ordered O2s given the 2C2D error code that comes back. Also had a cylinder 5 misfire during a quick loaded log. Otherwise no codes from MHD.

Will be checking out plugs, coils. Both are new in last month when I swapped to the NXM B58 kit. Coils are B58 eldors. But logs look fuel related.

Injectors are index 12 but 4 years old now.

Have tried resetting O2s, restarting, clearing codes but seemed to get worse over a 10 mile drive home so it's parked. Car gave me no issues until the drive home from work today, idle destabilized at a light and car generally feels like it's down a cylinder.

Multiple logs in this datalog post.

 
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ShocknAwe

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Jan 24, 2018
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Figured I'd update, I prefer transparency and I'll document whatever I find.

Im ordering new sensors and injectors, and hopefully compression test tomorrow. Photo of plugs below, cyl1 is left/top. As you see one of these things is not like the other., and reeks of fuel. Interesting to me since bank 2 read lean day of event and has been grossly fine until yesterday.

My bet unfortunately is that cyl5 is done, I'm a pessimist and I don't believe it survived the lean AFRs I saw on logs, even if just a 10mi drive home and one short pull. If so there will be a N54 part out and I start shopping for a E92 donor car.

No cart before the horse though.
 

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SlowE93

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Why 4&6? Educate me.

AFRs quite lean. Did one quick when I got home with it still idling and saw 19-20 and shut it down.
Cyl 5 is the black plug ?
If so, and I did not check logs but, if so, then cyl 5 would piss out fuel running a rich condition as read by the 02. The DME will then pull fuel to try and get trims and AFR in check. This would make cyl 4 and 6 actually leaner than 5 because 5 is overly rich already.
Our cars read bank to bank fuel trims, not per cylinder. So when DME either adds or pulls fuel, it will do 3 cyl, not just the one that actually needs it.
In this case, if that is the #5 plug running overly rich, DME will pull fuel in bank 2 affecting all cylinders, but once again, if read per cylinder, 4 and 6 would be leaner than 5.
 

ShocknAwe

Captain
Jan 24, 2018
1,491
1
737
0
Charleston, SC
Ride
N54/3 1er ///Mutt
Cyl 5 is the black plug ?
If so, and I did not check logs but, if so, then cyl 5 would piss out fuel running a rich condition as read by the 02. The DME will then pull fuel to try and get trims and AFR in check. This would make cyl 4 and 6 actually leaner than 5 because 5 is overly rich already.
Our cars read bank to bank fuel trims, not per cylinder. So when DME either adds or pulls fuel, it will do 3 cyl, not just the one that actually needs it.
In this case, if that is the #5 plug running overly rich, DME will pull fuel in bank 2 affecting all cylinders, but once again, if read per cylinder, 4 and 6 would be leaner than 5.

Thanks. Makes perfect sense that it was all compensation for Cyl5 injector stuck wide open. Guess we'll see what compression numbers are and how the car runs with new injectors. Hoping rough idle is due to 5 drowning in fuel.
 

SLOWESTN54

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I'd say your cylinder 4 and 6 plugs look comparable to 1, 2, 3. I wouldn't over think it too much. Leak down tester will give you all your answers if you wanna check before buying injectors tho.
 
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ShocknAwe

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Jan 24, 2018
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Charleston, SC
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N54/3 1er ///Mutt
I'd say your cylinder 4 and 6 plugs look comparable to 1, 2, 3. I wouldn't over think it too much. Leak down tester will give you all your answers if you wanna check before buying injectors tho.

Bought some can always part them out. Paying into some good faith that it'll work out.

Edit: Didn't have a compression tester so like a bonehead I rented one. What a piece of trash. Returning that tomorrow. Went online and OTC vs Mityvac seem to be quality for the price. The Mityvac appears to come with the 12mm attachment, it'll allegedly be here tomorrow as well from Amazon. We'll see.
 
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ShocknAwe

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Jan 24, 2018
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N54/3 1er ///Mutt
It's here. Should be the real deal. Has 10/12/14/18mm attachments and an "air hold adapter"

Quick detach is quality and has replacement valves and rings included.

Testing once my wife is around to watch the dial. If numbers are sadness inducing I will try to bore scope the cylinder in question with my cheap scope and post the photos.
 

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ShocknAwe

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Procedure: pulled plugs and coils, disconnected coils from harness. Pulled fuel pump fuse (which I promptly dropped behind the passenger footwell plastic, fuck I always drop something!!). Connect tester and 12mm adapter and crank engine over until max pressure reached.

Results. I tried 3 different testers. One from AutoZone, one cheap one from Amazon, and the Mityvac. The two cheap ones were chaos. I was getting readings all over the map like 110-140. The Mityvac did not return the 180s like I was hoping. However the numbers were consistent and repeatable.

This was done twice with the Mityvac. Each cylinder came to full pressure in approximately 6 cranks. Numbers in range reported. They were like 152 vs 157 vs 155 but it's hard to tell, so reporting what 5per band they showed up in.

Cyl1 - 150-155
Cyl2 - 155-160
Cyl3 - 150-155
Cyl4 - 155-160
Cyl5 - 155-160
Cyl5 - 155-160

Since I didn't get into the 170-180 range and didn't have other beefier orings to try seal troubleshooting, I scoped the pistons and walls, OTHER THAN FUEL RESIDUE, I think everything looks pretty good! Photos of the scope screen below, hard to juggle sorry they're crappy.

So all in hand, I'm gonna put in new O2s, new injectors, code it all up, and let her rip. (Gotta find that fuse too, time to go find a T25...)
 

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SlowE93

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Jul 2, 2017
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Procedure: pulled plugs and coils, disconnected coils from harness. Pulled fuel pump fuse (which I promptly dropped behind the passenger footwell plastic, fuck I always drop something!!). Connect tester and 12mm adapter and crank engine over until max pressure reached.

Results. I tried 3 different testers. One from AutoZone, one cheap one from Amazon, and the Mityvac. The two cheap ones were chaos. I was getting readings all over the map like 110-140. The Mityvac did not return the 180s like I was hoping. However the numbers were consistent and repeatable.

This was done twice with the Mityvac. Each cylinder came to full pressure in approximately 6 cranks. Numbers in range reported. They were like 152 vs 157 vs 155 but it's hard to tell, so reporting what 5per band they showed up in.

Cyl1 - 150-155
Cyl2 - 155-160
Cyl3 - 150-155
Cyl4 - 155-160
Cyl5 - 155-160
Cyl5 - 155-160

Since I didn't get into the 170-180 range and didn't have other beefier orings to try seal troubleshooting, I scoped the pistons and walls, OTHER THAN FUEL RESIDUE, I think everything looks pretty good! Photos of the scope screen below, hard to juggle sorry they're crappy.

So all in hand, I'm gonna put in new O2s, new injectors, code it all up, and let her rip. (Gotta find that fuse too, time to go find a T25...)
Quit being a fuckn sissy and put that shit back together. 😡
I told you most likely you are fine (no homo)
Don't come back till car is running ✌🏾
 
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