Bank 1 / 2 AFR deviation

[xShadows]

Installed Vargas GC turbos and tossed on the BM3 Stage 2 93 map. Car pulls fine, but breaks up around 6300, AFR gets weird on Bank 1. Anyone have any ideas what might cause this? Fuel injector possibly?

https://datazap.me/u/xshadows/log-15...3&zoom=146-175

EDIT: Mods:

Vargas GC+ turbos
Catless DPs
VRSF Intake / CP's
NGK plugs
CFS Heat exchanger

[smiff]

I would skip the OTS map, and have one of the well known tuners custom tune it.

[xShadows]

Originally Posted by smiff

I would skip the OTS map, and have one of the well known tuners custom tune it.

It will get a proper tune as soon as I verify everything is ok on the OTS map. No reason to fight hardware issues and waste a tuners time.

[MR RIZK]

Do u have the same issue with the stock tune as u mentioned you changed both turbo and tune at the same time.

Not the easiest but you could swap banks for the injectors if you suspect this but keep in mind u need to code them and be wary of the injector seals expanding.

Check if you have a air leak post maf sensor as that will throw out the banks as it is unmetered air.

In essence do all the simple checks first and swap what u can from bank 1 and 2 and see if the issue moves.

[xShadows]

Originally Posted by MR RIZK

Do u have the same issue with the stock tune as u mentioned you changed both turbo and tune at the same time.

Not the easiest but you could swap banks for the injectors if you suspect this but keep in mind u need to code them and be wary of the injector seals expanding.

Check if you have a air leak post maf sensor as that will throw out the banks as it is unmetered air.

In essence do all the simple checks first and swap what u can from bank 1 and 2 and see if the issue moves.

It does the same thing on the stock tune, stage 1 tune, custom tune and hybrid tune.

It's been pressure tested and smoke tested, no leaks. You'd think if unmetered air was getting into the system it would have this issue a lot sooner than 6300rpm.

[MR RIZK]

Do u know if the car goes into open loop under load? As this will rule out the O2 sensor.

Not sure if possible but can you swap the maf between banks.

Anything else changed at the same time? I can see u listed the mods but not sure if it was at the same time as the issue started.

[xShadows]

Originally Posted by MR RIZK

Do u know if the car goes into open loop under load? As this will rule out the O2 sensor.

Not sure if possible but can you swap the maf between banks.

Anything else changed at the same time? I can see u listed the mods but not sure if it was at the same time as the issue started.

Everything installed was:

Intercooler / heat exchanger / J pipe
Pinned crank hub
Turbos
Downpipes
Plugs / coils

[xShadows]

We even ran the injector test with ISTA to rule that out, but I'm not so sure how accurate that is.

[BlownOne]

I ran the 93 stage2 file a month ago on my way home from EaS and didn’t have any issues at all wot or cruising.

You shouldn’t have any issue keeping up with 12.0 target afr on gasoline as that file runs 21-22psi. Looks like a fuel delivery issue to me: pump, injector, o-ring or fuel line.

[BB6]

Sounds like a boost leak but if you smoked it already and nothing, then it may be something as simple as plug gap. Your running the 2 step colder plug I am assuming by your post, but whats your gap. With those turbos upping the airflow you may be getting blow out and with trying the stock tune and the BM3 stg2 93 you really are getting the proper tune Air/Fuel ratios from the DME for those turbos. Check your plug gaps, get a proper tune and then if you still have AFR issues the Tuner will actually see it during his tuning process and will help you trouble shoot it. If you weren't having the issues before you put on the VTT turbos then most likely its something really simple like a leak or tune, but I highly doubt injectors.

[BB6]

Originally Posted by BB6

Sounds like a boost leak but if you smoked it already and nothing, then it may be something as simple as plug gap. Your running the 2 step colder plug I am assuming by your post, but whats your gap. With those turbos upping the airflow you may be getting blow out and with trying the stock tune and the BM3 stg2 93 you really are getting the proper tune Air/Fuel ratios from the DME for those turbos. Check your plug gaps, get a proper tune and then if you still have AFR issues the Tuner will actually see it during his tuning process and will help you trouble shoot it. If you weren't having the issues before you put on the VTT turbos then most likely its something really simple like a leak or tune, but I highly doubt injectors.

Forgot to mention, it took me 3 times smoking my system before I found my boost leak and it was as simple as tightening a clamp.

[xShadows]

Originally Posted by BB6

Sounds like a boost leak but if you smoked it already and nothing, then it may be something as simple as plug gap. Your running the 2 step colder plug I am assuming by your post, but whats your gap. With those turbos upping the airflow you may be getting blow out and with trying the stock tune and the BM3 stg2 93 you really are getting the proper tune Air/Fuel ratios from the DME for those turbos. Check your plug gaps, get a proper tune and then if you still have AFR issues the Tuner will actually see it during his tuning process and will help you trouble shoot it. If you weren't having the issues before you put on the VTT turbos then most likely its something really simple like a leak or tune, but I highly doubt injectors.

2 step colder plugs gapped to .22. Should I take them down to .18?

[BB6]

Originally Posted by xShadows

2 step colder plugs gapped to .22. Should I take them down to .18?

from what I understand I would. I was having the same break up issue and tried .024, still had the problem in the 6K rpm range. Then gapped them to .019 and went away. has been great for 2yrs now. i really do feel you need a tune though or you may just keep chasing hardware issues that aren't there. Gap the plugs, maybe smoke it again just to make sure and get a reputable tuner involved. Hope you figure it out man. Learn to do all the trouble shooting yourself so you don't cringe and shy away from mechanic costs. Hardest part of trouble shooting these cars is time and money. Try to eliminate the money part on simple things.

[xShadows]

Originally Posted by BB6

from what I understand I would. I was having the same break up issue and tried .024, still had the problem in the 6K rpm range. Then gapped them to .019 and went away. has been great for 2yrs now. i really do feel you need a tune though or you may just keep chasing hardware issues that aren't there. Gap the plugs, maybe smoke it again just to make sure and get a reputable tuner involved. Hope you figure it out man. Learn to do all the trouble shooting yourself so you don't cringe and shy away from mechanic costs. Hardest part of trouble shooting these cars is time and money. Try to eliminate the money part on simple things.

When it was breaking up was it going lean or rich? This is a lean issue, if there was unburnt fuel due to bad spark or gap, it would be rich.

[cbrtrx]

Originally Posted by xShadows

When it was breaking up was it going lean or rich? This is a lean issue, if there was unburnt fuel due to bad spark or gap, it would be rich.

Misfires would register as a lean condition on an o2, not rich. Unburnt fuel is not measured by an o2 sensor, oxygen is or the lack there of.

[BB6]

Originally Posted by cbrtrx

Misfires would register as a lean condition on an o2, not rich. Unburnt fuel is not measured by an o2 sensor, oxygen is or the lack there of.

right on it. try the things I mentioned and hopefully that will make a difference. Smoke test again just to make sure. Gap the plugs down. After gapping the plugs down if you see even a little bit of difference (maybe it breaks up less, or maybe its breaking up at 7,000 instead of 6,300) then at least you know your heading in the right direction. In my experience I would not gap your plugs tighter than .018. But really, you need to get a tuner involved. By no means am I a professional, just trying to share my experience. A tuner will be able to pinpoint a lot of trouble shooting and save you some time. If he sees issues with your logs other than natural adjustments that need to be made for upgraded turbos then he will ask you to confirm a few items like; specified plugs & gap, type of fuel you were running, did you check for boost leaks, etc. Stick with it man, you will get it resolved.