2025 I6 - JB4 Tuner

[wvinson]

after doing each sensor one at a time and testing, it finally works as intended. easy install, pain to troubleshoot.

thats why I had my shop do mine

 

[RobL]

Considering purchasing the JB4 and seeking additional reviews.

I'd like to share lessons learned and some experience with the JB4 tuner. I have a 2025 Ram 1500 Limited with the HO Hurricane. I installed the JB4 and yes it makes crazy HP and really throws you back into your seat. Instant smile. BUT.... As with anything there some problems. One, there is a known software issue with the Rams running the HO. There is a rapid response update that supposedly fixes it. What happens is that the catalytic converters cannot handle the amount of heat and the software issue causes some unburnt fuel to reach the converters where is ignites. Over time the Honeycomb inside structure begins to melt and slowly clogs the converters. You will see a major reduction in power and eventually CEL. The JB4 speeds up this process and will completely clog both converters in about 6 months. If you have the update then it will take longer but the amount of heat these engines produce are too much for the stock converters.

The second issue, the engine compartment also gets very hot and the metal JB4 casing will get so hot that you can't even touch it. When the tuner overheats it will cause some brief connection issues. If this occurs when you are getting into the throttle it will blow the turbo hose off and the motor will stall. If your motor starts losing power suddenly and chugs along barely running then it probably blew off the turbo hose.

If you decide to continue to run the JB4 I wouldn't use anything higher than map #2. Map #3 and higher needs blended fuel and even then it will exceed the max PSI value and you will eventually run into problems.

Suggestions... buy some wire and connectors to lengthen all 3 JB4 harnesses and keep the tuner inside the truck. Never use anything higher than Map #2. Daily driving keep factory settings on the app and only use the maps when needed.

Overall the JB4 does what it says very well but has negative side effects on the motor. All depends on how you use it.

 

[wvinson]

I'd like to share lessons learned and some experience with the JB4 tuner. I have a 2025 Ram 1500 Limited with the HO Hurricane. I installed the JB4 and yes it makes crazy HP and really throws you back into your seat. Instant smile. BUT.... As with anything there some problems. One, there is a known software issue with the Rams running the HO. There is a rapid response update that supposedly fixes it. What happens is that the catalytic converters cannot handle the amount of heat and the software issue causes some unburnt fuel to reach the converters where is ignites. Over time the Honeycomb inside structure begins to melt and slowly clogs the converters. You will see a major reduction in power and eventually CEL. The JB4 speeds up this process and will completely clog both converters in about 6 months. If you have the update then it will take longer but the amount of heat these engines produce are too much for the stock converters.

The second issue, the engine compartment also gets very hot and the metal JB4 casing will get so hot that you can't even touch it. When the tuner overheats it will cause some brief connection issues. If this occurs when you are getting into the throttle it will blow the turbo hose off and the motor will stall. If your motor starts losing power suddenly and chugs along barely running then it probably blew off the turbo hose.

If you decide to continue to run the JB4 I wouldn't use anything higher than map #2. Map #3 and higher needs blended fuel and even then it will exceed the max PSI value and you will eventually run into problems.

Suggestions... buy some wire and connectors to lengthen all 3 JB4 harnesses and keep the tuner inside the truck. Never use anything higher than Map #2. Daily driving keep factory settings on the app and only use the maps when needed.

Overall the JB4 does what it says very well but has negative side effects on the motor. All depends on how you use it.

So, are you saying that if you don't get the rapid response update and don't have the tuner that all HO engines will melt their catalytic converters. That sounds a little absurd. The HO engine has been out for 3 years running in the Grand Wagoneer.

 

[BowDown]

C6 Corvette ZR1s were having an issue with melting cats with repeated long pulls. It takes a while to get to that point but there's been no fix short of going cat-less or less/shorter full power pulls.

High flow cats didn't last any longer, actually shorter. The only thing that helped the cats was adding fuel to cool the cats, that maybe something the tuners need to reconsider

 

[CalvinC]

That sounds to me like the tune runs on the lean side. Not good.

And if anything I’d think the e-blend maps would lower the egts?

 

[BowDown]

That sounds to me like the tune runs on the lean side. Not good.

And if anything I’d think the e-blend maps would lower the egts?

No, the engine can be in its ideal range under boost, probably in the 11-12's but that be too lean to keep the cats from overheating under high load conditions.
Adding fuel to help the cats would reduce power. Possibly switching to a metal matrix cat.

An E blend would help but you'd need a flex fuel sensor that could detect ethanol content and adjust the tune accordingly and a corresponding tune. Your only other option would be buying drums of ignite or something sooner that had a consistent E content then tune for that but that would eliminate your ability to use pump gas

 

[CalvinC]

No, the engine can be in its ideal range under boost, probably in the 11-12's but that be too lean to keep the cats from overheating under high load conditions.
Adding fuel to help the cats would reduce power. Possibly switching to a metal matrix cat.

An E blend would help but you'd need a flex fuel sensor that could detect ethanol content and adjust the tune accordingly and a corresponding tune. Your only other option would be buying drums of ignite or something sooner that had a consistent E content then tune for that but that would eliminate your ability to use pump gas

That’s what I’m saying, tune may be a bit too spicy for the sake of marketing. Reducing power is not as sexy, but neither are melted cats.

 

[TerryRamTuner]

I'd like to share lessons learned and some experience with the JB4 tuner. I have a 2025 Ram 1500 Limited with the HO Hurricane. I installed the JB4 and yes it makes crazy HP and really throws you back into your seat. Instant smile. BUT.... As with anything there some problems. One, there is a known software issue with the Rams running the HO. There is a rapid response update that supposedly fixes it. What happens is that the catalytic converters cannot handle the amount of heat and the software issue causes some unburnt fuel to reach the converters where is ignites. Over time the Honeycomb inside structure begins to melt and slowly clogs the converters. You will see a major reduction in power and eventually CEL. The JB4 speeds up this process and will completely clog both converters in about 6 months. If you have the update then it will take longer but the amount of heat these engines produce are too much for the stock converters.

The second issue, the engine compartment also gets very hot and the metal JB4 casing will get so hot that you can't even touch it. When the tuner overheats it will cause some brief connection issues. If this occurs when you are getting into the throttle it will blow the turbo hose off and the motor will stall. If your motor starts losing power suddenly and chugs along barely running then it probably blew off the turbo hose.

If you decide to continue to run the JB4 I wouldn't use anything higher than map #2. Map #3 and higher needs blended fuel and even then it will exceed the max PSI value and you will eventually run into problems.

Suggestions... buy some wire and connectors to lengthen all 3 JB4 harnesses and keep the tuner inside the truck. Never use anything higher than Map #2. Daily driving keep factory settings on the app and only use the maps when needed.

Overall the JB4 does what it says very well but has negative side effects on the motor. All depends on how you use it.

Just to clear up any misinformation here.

1) The issue with the defunct factory ECU programming causing issues with the factory cats has nothing at all to do with the JB4. The JB4 is not active at idle/low load when this issue occurs and the JB4 will neither help nor make worse the issue. The only fix is the updated ECU programming from RAM. If you're going to have that issue you'll have it either way.

2) The JB4 is rated over 300F and heat is not a concern for the system. The box should be located to the left of the air intake box per our install guide and in this location, it will generally be around 140F or lower.

3) Blowing off a chargepipe connection at higher maps/boost levels just means it was not clamped on tight enough. I've not seen many instances of it but had at least two reported. Just reattach and ensure the clamp is tight.

4) We encourage all users to follow the provided map guide. For 93 octane generally that means map2, and for those mixing in E85 in HO motors you can go up to map3 or map4 if you're looking for more power.

Generally speaking, DO NOT alter, lengthen, or otherwise change your JB4 harness wiring. And if you have any tuning or concerns, contact JB4 support with your JB4 log for assistance.

 

[TerryRamTuner]

That’s what I’m saying, tune may be a bit too spicy for the sake of marketing. Reducing power is not as sexy, but neither are melted cats.

The JB4 isn't melting any cats and all maps were developed with EGT monitoring. The Hurricanes have a weird factory defect where the ECU programming randomly dumps unburnt fuel at idle and melts the cat. I believe it's been fixed, but there were lots of reports of the issue on factory-tuned trucks.

 

[CalvinC]

The JB4 isn't melting any cats and all maps were developed with EGT monitoring. The Hurricanes have a weird factory defect where the ECU programming randomly dumps unburnt fuel at idle and melts the cat. I believe it's been fixed, but there were lots of reports of the issue on factory-tuned trucks.

That’s probably really good you chimed in Terry. Because the OP’s wording and/or my reading comprehension definitely made it sound like the melty cat issues were specifically due to running the Jb4.

And while I don’t follow every Hurricane thread on the internet, I hadn’t seen talk of melted cats until now, so it was believable to me.

 

[TerryRamTuner]

That’s probably really good you chimed in Terry. Because the OP’s wording and/or my reading comprehension definitely made it sound like the melty cat issues were specifically due to running the Jb4.

And while I don’t follow every Hurricane thread on the internet, I hadn’t seen talk of melted cats until now, so it was believable to me.

I believe this is the TSB for the root cause: https://static.nhtsa.gov/odi/tsbs/2025/MC-11015519-0001.pdf

There are reports of melted cats as a result in the FB groups, likely on this forum as well, too lazy to go search for them.