3.3TT Intermittent Limp Mode & CEL at 2K RPM – 2020 Kia Stinger GT2 (JB4 MAP 1, No Codes)

[CasperGT2]

2020 KIA Stinger GT2

Here are my specifications:

- K&N CAI

- MBRP catback exhaust

- DC Sports Mid pipes

- Single ADD W1 Catch Can

- JB4 with EWG wires and fuel wires (JB4 was recently installed on January 31, 2026)

- Brand new ignition coils

- Brand new HKS plugs gapped to 0.022

- I only use 94 octane or 93, no lower

- Running MAP 1



I spoke to Terry at Burger Motorsport, and honestly, he wasn’t very helpful. He was extremely vague and told me to change FF from 50 to 30. All his emails were also vague and didn’t provide much help in diagnosing my issue. So, I’m reaching out to you all to see if you can assist me.


I want to avoid going to a dealership and fix it myself if possible.


For a while now, I’ve been experiencing issues where, around 2,000 rpm or a little less, the car would randomly enter some type of limp mode or protection mode. It barely allowed me to accelerate, even if I floored the gas pedal. Additionally, it would display a CEL. When I scan the car right when it comes on, no errors are shown. Even after turning the car off and on in accessory mode, as recommended, there are still no errors. However, when I turn the car all the way over, the engine light goes off, and everything returns to normal until it happens again.



I read that changing the ignition coils and spark plugs should fix the issue, but it didn’t. I changed both together and gapped the plugs (0.022).



Now, I’m undergoing some testing, and Terry told me to adjust the FF/Wastegate from 50 to 30. That seemed to help quite a bit because it was happing more frequent if I remember correctly! However, I can still get it to happen if I do a spirited drive, then slow down to come to a stop. Then, I accelerate normally, but if I take my foot off the gas pedal to slow and and let the RPMs drop to around 2,000 rpm or a little lower, and then accelerate normally to get the car to move forward more, the car will cut a lot of power. This results in a CEL, forcing me to pull over, turn the car off, and then turn it back on again.

I’ve tried recreating it by getting to those low rpms without accelerating hard beforehand, but I couldn’t reproduce the problem.



Today, I tested again, but this time I set JB4 to map 0. I drove for an hour, spirited here and there when I could and testing it often as I lowered the rpms to around 1,500-2,000, trying to recreate the issue. However, it didn’t happen once. Everything felt fine and as it should.



I need your input on this. Is there a setting in JB4 that I can adjust to help more?



The settings in JB4 were actually set as recommended on the website where I purchased the EWG wires. Here are the settings I have set to:

- Duty Bias: All to 50

- FF/Wastegate: 30 (was set to 50)

- PID gain: 20

- Auto shift reduction: 60



I was able to log it one time when I sent it to Terry. Not sure if it helps or not. But it did happen when I was logging. He wasn’t clear from this log what the issue is…

 

[Plakchup]

Can you post your jb4 settings page? Double check to make sure default wastegate pos is set to 0. I am assuming you did not have this issue until you installed jb4? Since map 0 does not cause this overboost limp mode issue it makes me think its some setting in jb4.

I dealt with overboost issues as well until I got jb4 with ewg wires and lowered wastegate adaptations to about 45 and always got nice clean logs.

 

[CasperGT2]

Can you post your jb4 settings page? Double check to make sure default wastegate pos is set to 0. I am assuming you did not have this issue until you installed jb4? Since map 0 does not cause this overboost limp mode issue it makes me think its some setting in jb4.

I dealt with overboost issues as well until I got jb4 with ewg wires and lowered wastegate adaptations to about 45 and always got nice clean logs.

Thank you for your reply! I have ff/Wastegate set to 30 (originally it was 50 until Terry told me to drop it), not 0. Unless there is another segment specifically labeled as “Wastegate”? I’m using the JB4 PRO app so the layout is a little different than the other app.
But correct, map 0 doesn’t trigger it. Just when I change to map 1 (haven’t tried map2 as I’d want to figure out this issue before going higher). But I definitely feel like it’s something I need to tweak in the JB4 pro app. I just have no idea what lol

 

[Plakchup]

Doh I am using the regular jb4 app. I think you probably need to as well. I know the jb4 pro bluetooth chip is the new thing out installed in recent jb4 kits sold but I am not sure about the jb4 pro app. Also I know there is no jb4 pro hardware kit out for stinger. It is only for very few vehicles.

Generally the wategate adaptions doesn't need to be that low unless you running high flows/catless primaries. The other settings you mentioned seem fine they are the same on mine. There should be an options setting somewhere in jb4. Make sure fuel bias is all set to 0 as well. Here are my settings before I went BEF. After bef we disabled the fuel wires and also physically removed them put it back to stock. Ewg wires are there but are not doing anything and the ecu bef overwrites them anyway. Learned this when we were doing KJT bef.

 

[CasperGT2]

Doh I am using the regular jb4 app. I think you probably need to as well. I know the jb4 pro bluetooth chip is the new thing out installed in recent jb4 kits sold but I am not sure about the jb4 pro app. Also I know there is no jb4 pro hardware kit out for stinger is only for very few vehicles.

Generally the wategate adaptions doesn't need to be that low unless you running high flows/catless primaries. The other settings you mentioned seem fine they are the same on mine.

So are you saying I should switch to the older JB4 app? And make my settings what exactly?
I don’t necessarily have high flow mods. But changing ff from 50 to 30 did seem to help initially. Till I tested and found map 0 doesn’t do the issue.

 

[Plakchup]

I havent heard of any stinger owners using the jb4 pro app. Don't quote me on this but i think its not available yet for the stinger since there is no jb4 pro hardware kit out yet for the stinger. It's a bit confusing. Maybe that's why its causing issues. Sent you a DM. Might be easier to chat than tons of replies.

 

[CasperGT2]

Doh I am using the regular jb4 app. I think you probably need to as well. I know the jb4 pro bluetooth chip is the new thing out installed in recent jb4 kits sold but I am not sure about the jb4 pro app. Also I know there is no jb4 pro hardware kit out for stinger. It is only for very few vehicles.

Generally the wategate adaptions doesn't need to be that low unless you running high flows/catless primaries. The other settings you mentioned seem fine they are the same on mine. There should be an options setting somewhere in jb4. Make sure fuel bias is all set to 0 as well. Here are my settings before I went BEF. After bef we disabled the fuel wires and also physically removed them put it back to stock. Ewg wires are there but are not doing anything and the ecu bef overwrites them anyway. Learned this when we were doing KJT bef.

i didn’t see your whole message till now. Okay I’ll try these settings and use the older JB4 app, not the pro one and see what happens.