Single turbo n54 misfire cyl 5

[jackobrien2256]

Hey guys,

I have been trying to chase down this misfire I have been having. Switched around injectors, coil packs, spark plugs, and pi injectors.
Turned off pi and car ran slightly better. Car still misfired with pi turned off but not nearly as bad. Just replaced o2 sensors.

Currently maxing out the trims on both banks.
If anyone has some advice I’d greatly appreciate it.

 

[jackobrien2256]

datazap.me | Jackobrien2256 | Pi turned off

datazap.me

Here is a log

 

[jackobrien2256]

Misfire only happens in high RPM and boost.

 

[N54TT]

Are you sure your port injection is working? I mean to my basic knowledge I would think 16 psi of boost with 1300 psi of fuel pressure is pretty damn low and you're running LEAN as fuck 17 AFR lol don't do anymore pulls you're going to blow shit up until you get this resolved.

 

[jackobrien2256]

Are you sure your port injection is working? I mean to my basic knowledge I would think 16 psi of boost with 1300 psi of fuel pressure is pretty damn low and you're running LEAN as fuck 17 AFR lol don't do anymore pulls you're going to blow shit up until you get this resolved.

I assume pi is all working. What would be a good way to test? I turned off pi for a log and still misfired showed in the log above. Ordered a new index 12 for cyl 5. Not going to do anymore pulls but I am at at lost as of now. Thanks for the feedback

 

[N54TT]

I assume pi is all working. What would be a good way to test? I turned off pi for a log and still misfired showed in the log above. Ordered a new index 12 for cyl 5. Not going to do anymore pulls but I am at at lost as of now. Thanks for the feedback

If your tune is set for PI I would not turn it off because all that extra fuel I assume would make the car run more rich so the tune itself is dialed in to run more lean, but don't take my word I'm just using basic knowledge. Plug in your PI and do another run, but monitor your AFR if you see it lean as hell don't do anymore pulls. Have you reached out to your tuner? Keep in mind worn DMFW can cause high rpm misfires on cylinder #5 and cylinder #6.

 

[jackobrien2256]

If you're tune is set for PI I would not turn it off because all that extra fuel I assume would make the car run more rich so the tune itself is dialed in to run more lean, but don't take my word I'm just using basic knowledge. Plug in your PI and do another run, but monitor your AFR if you see it lean as hell don't do anymore pulls. Have you reached out to your tuner? Keep in mind worn DMFW can cause high rpm misfires on cylinder #5 and cylinder #6.

My tuner left me to dry a couple months back. Trying to get some other tuners opinions on it. One tuner said it’s either a o2 or injector problem. I just replaced both o2’s with Bosch oem since I’ve had no luck with NKT’s. Index 12 should be here tomorrow. I also have a SMFW.

 

[N54TT]

My tuner left me to dry a couple months back. Trying to get some other tuners opinions on it. One tuner said it’s either a o2 or injector problem. I just replaced both o2’s with Bosch oem since I’ve had no luck with NKT’s. Index 12 should be here tomorrow. I also have a SMFW.

It’s time to get a new tuner my man.

 

[jackobrien2256]

It’s time to get a new tuner my man.

Been working on that. Seems to me like a lot of tuners don’t like to spend the time to look at logs if the car isn’t already tuned by them.

 

[N54TT]

Been working on that. Seems to me like a lot of tuners don’t like to spend the time to look at logs if the car isn’t already tuned by them.

Just purchase a new tune and start from scratch with a base tune and a list of all your modifications.

 

[jackobrien2256]

Just purchase a new tune and start from scratch with a base tune and a list of all your modifications.

Will do. Thanks for the advice

 

[SLOWESTN54]

Will do. Thanks for the advice

Ken from @WedgePerformance is always pretty helpful

 

[jackobrien2256]

Ken from @WedgePerformance is always pretty helpful

Just purchased a Motive tune, hoping the guys there can help me out.

 

[Lofuel]

You need to log fuel mode , car could be going open loop and dumping fuel causing misfire on bank 2

 

[WedgePerformance]

Normally when you have bad injectors you can see fluctuations in RPM and eventually the injector misfires lead to fuel mode 15 which shut down o2 sensors and fuel trims go 0. This opens up the injector window and if you had a wideband you would see the car goes rich and ends up with a hard misfire most of the time. You can run a really hot coil like the B58 coil to eliminate some of the issues of bad injectors, but due to the fact we don't have AFR readings for each cylinder, a leaking injector can cause the other cylinders on that bank to run out lean. Nothing worse than a bad injector and the #1 cause of engine failure on this platform. If you're spending money on a custom tune when chasing a mechanical issue, I hate to say it, but you probably just wasted your money and you're not going to get the level of support you need to fix the issue because the car won't be tunable. I tell people to replace injectors almost every day on this platform. Two things that are the most overlooked items, injectors and hot coils.

 

[jackobrien2256]

Normally when you have bad injectors you can see fluctuations in RPM and eventually the injector misfires lead to fuel mode 15 which shut down o2 sensors and fuel trims go 0. This opens up the injector window and if you had a wideband you would see the car goes rich and ends up with a hard misfire most of the time. You can run a really hot coil like the B58 coil to eliminate some of the issues of bad injectors, but due to the fact we don't have AFR readings for each cylinder, a leaking injector can cause the other cylinders on that bank to run out lean. Nothing worse than a bad injector and the #1 cause of engine failure on this platform. If you're spending money on a custom tune when chasing a mechanical issue, I hate to say it, but you probably just wasted your money and you're not going to get the level of support you need to fix the issue because the car won't be tunable. I tell people to replace injectors almost every day on this platform. Two things that are the most overlooked items, injectors and hot coils.

Swapped coils and injectors around misfire did not follow.

 

[WedgePerformance]

Swapped coils and injectors around misfire did not follow.

Sounds like it's time to do a compression test. Before you do that, put a new plug in that hole to see if you have a bad NGK. They are a 5k Ohm plug and most test around 4.5k Ohm, but when they drop below 4k Ohm they have a tendency to cause misfires.

 

[jackobrien2256]

Sounds like it's time to do a compression test. Before you do that, put a new plug in that hole to see if you have a bad NGK. They are a 5k Ohm plug and most test around 4.5k Ohm, but when they drop below 4k Ohm they have a tendency to cause misfires.

Did a compression test and everything checked out. I also put a brand new plug in and gapped to .018 but nothing changed. I thought about maybe msd80 causing problems but that is a long shot.

 

[WedgePerformance]

Did a compression test and everything checked out. I also put a brand new plug in and gapped to .018 but nothing changed. I thought about maybe msd80 causing problems but that is a long shot.

Unfortunately shit like this ends up costing $$$$ to figure out. Get with Levan at BIMECU.com to see what his inventory status is. He's probably the best guy to go to for swapping the ECU. His process doesn't cause you to lose your licenses like some.

 

[jackobrien2256]

Unfortunately shit like this ends up costing $$$$ to figure out. Get with Levan at BIMECU.com to see what his inventory status is. He's probably the best guy to go to for swapping the ECU. His process doesn't cause you to lose your licenses like some.

Thanks for the advice. Will get in touch with Levan and do a follow up if anything changes.