Dreaded hemi manifold leak

[Bryansimmons24]

I recently had the dreaded manifold leak. I did not want to have the issue again so I upgraded to BBK shorty headers. Same shorty length as OEM. Now I have a check engine light for O2 sensors. Is this going to require reprogram of the PCM/ECM or is it a bad O2 sensor. Asking for advice from others who had same issue.

 

[PM-Performance]

You probably have a bad o2 or bad connection to the o2.
Cels only really come on if you don’t plug them back in or have lack of catalyst (ie: remove cats and the sensor is post cat.

 

[dearmosd]

New guy here, but did you say there is a manifold leak issue with the hemi's? I just purchased a 2021 Laramie and when I started it I thought it sounded like it had an exhaust leak near the front driver side wheel well.....drove it for a min then checked again and I could not hear it....I questioned if cold metal caused a leak and when it warmed up if sealed itself back off.

 

[dts828]

I recently had the dreaded manifold leak. I did not want to have the issue again so I upgraded to BBK shorty headers. Same shorty length as OEM. Now I have a check engine light for O2 sensors. Is this going to require reprogram of the PCM/ECM or is it a bad O2 sensor. Asking for advice from others who had same issue.

I would check the bolts and nuts that connect the headers to cats are super tight and flanges are seated correctly. I had shorty's on my 300C and the bolts/nuts liked to come loose and throw codes. I ended up double nutting each bolt to fix the problem.

Sent from my SM-S918U1 using Tapatalk

 

[HSKR R/T]

New guy here, but did you say there is a manifold leak issue with the hemi's? I just purchased a 2021 Laramie and when I started it I thought it sounded like it had an exhaust leak near the front driver side wheel well.....drove it for a min then checked again and I could not hear it....I questioned if cold metal caused a leak and when it warmed up if sealed itself back off.

Yes, common issue to have the manifolds crack. As they warm up, metal expands and "seals" the crack.

 

[CHeYeNNe71]

I recently had the dreaded manifold leak. I did not want to have the issue again so I upgraded to BBK shorty headers. Same shorty length as OEM. Now I have a check engine light for O2 sensors. Is this going to require reprogram of the PCM/ECM or is it a bad O2 sensor. Asking for advice from others who had same issue.

Keep watch on the BBK as many have claimed they crack/break as well.

 

[MikeyHo808]

New guy here, but did you say there is a manifold leak issue with the hemi's? I just purchased a 2021 Laramie and when I started it I thought it sounded like it had an exhaust leak near the front driver side wheel well.....drove it for a min then checked again and I could not hear it....I questioned if cold metal caused a leak and when it warmed up if sealed itself back off.

I have had my passenger side replaced twice, my driver side once, all under warranty.
At cold start it is most noticeable. From your description, you may have a bad manifold.

 

[Bryansimmons24]

New guy here, but did you say there is a manifold leak issue with the hemi's? I just purchased a 2021 Laramie and when I started it I thought it sounded like it had an exhaust leak near the front driver side wheel well.....drove it for a min then checked again and I could not hear it....I questioned if cold metal caused a leak and when it warmed up if sealed itself back off.

Mine popped at 70,000 miles so no warranty to use. It sounds like a leak when cold started, but goes away when warmed up. Tell tell sign is while running you hear it right by the manifolds. Thought I'd beat the issue with upgraded headers but now I have to unlock my pcm and have a tune on it.

 

[Bryansimmons24]

You probably have a bad o2 or bad connection to the o2.
Cels only really come on if you don’t plug them back in or have lack of catalyst (ie: remove cats and the sensor is post cat.

I thought so too but as far as I can tell it's all plugged in and attached

 

[PM-Performance]

Mine popped at 70,000 miles so no warranty to use. It sounds like a leak when cold started, but goes away when warmed up. Tell tell sign is while running you hear it right by the manifolds. Thought I'd beat the issue with upgraded headers but now I have to unlock my pcm and have a tune on it.

You do not need to tune for headers
Exhaust work has absolutely nothing to do with a tune and vice versa.
The only relevance is if you want to shut off the sensors

 

[Bryansimmons24]

You do not need to tune for headers
Exhaust work has absolutely nothing to do with a tune and vice versa.
The only relevance is if you want to shut off the sensors

Well I'm having issues with O2 sensor causing CEL. I'm going to double check connections and maby get lucky.

 

[HSKR R/T]

You do not need to tune for headers
Exhaust work has absolutely nothing to do with a tune and vice versa.
The only relevance is if you want to shut off the sensors

That all depends. If you install longtubes, you definitely need to tune for them or they could actually hurt performance. Shorties, no, the PCM can compensate for those.

 

[bigdodge]

I recently had the dreaded manifold leak. I did not want to have the issue again so I upgraded to BBK shorty headers. Same shorty length as OEM. Now I have a check engine light for O2 sensors. Is this going to require reprogram of the PCM/ECM or is it a bad O2 sensor. Asking for advice from others who had same issue.

who did the work?

 

[PM-Performance]

That all depends. If you install longtubes, you definitely need to tune for them or they could actually hurt performance. Shorties, no, the PCM can compensate for those.

False
Again your tune knows nothing of anything exhaust wise. Even if you remove cats, all that will be done is shutting off the 02 feedback or mil status
Tunes are fuel/timing tables/maybe some shift points for autos and maybe some extra annoyance features.

 

[PM-Performance]

Well I'm having issues with O2 sensor causing CEL. I'm going to double check connections and maby get lucky.

I get that. A tune isn’t the answer.
Did you run the cel to see what it’s for? If so, what is the exact code?

 

[HSKR R/T]

False
Again your tune knows nothing of anything exhaust wise. Even if you remove cats, all that will be done is shutting off the 02 feedback or mil status
Tunes are fuel/timing tables/maybe some shift points for autos and maybe some extra annoyance features.

You are right, the tune itself doesn't know of anything exhaust related. It's just going to do what it's set to do in the tune parameters. Which means, if it can't compensate enough for the increase airflow, you could have worse performance, and/or detonate until it pulls enough timing to prevent lean detonation. If you don't plan on doing a custom tune for your mods don't modify the engine beyond CAI and shorty headers/catback exhaust

 

[PM-Performance]

You are right, the tune itself doesn't know of anything exhaust related. It's just going to do what it's set to do in the tune parameters. Which means, if it can't compensate enough for the increase airflow, you could have worse performance, and/or detonate until it pulls enough timing to prevent lean detonation. If you don't plan on doing a custom tune for your mods don't modify the engine beyond CAI and shorty headers/catback exhaust

How does an exhaust change airflow exactly?
There is literally nothing an exhaust will do to cause a lack of performance, or detonation or fueling changes or map/maf voltage changes.

Unless you personally are a tuner, you aren’t teaching me anything I do not already know about modding cars.
Sorry if that comes off wrong, but this falicy is spewed too much on the internet about tuning

 

[HSKR R/T]

How does an exhaust change airflow exactly?
There is literally nothing an exhaust will do to cause a lack of performance, or detonation or fueling changes or map/maf voltage changes.

Unless you personally are a tuner, you aren’t teaching me anything I do not already know about modding cars.
Sorry if that comes off wrong, but this falicy is spewed too much on the internet about tuning

Well shoot, they should just run stock manifolds on all high performance builds. I mean if headers and exhaust don't do anything to change performance, or airflow, why even change the exhaust. Im sure there are plenty of 1000hp cars running around on cast iron log manifolds.

 

[PM-Performance]

Well shoot, they should just run stock manifolds on all high performance builds. I mean if headers and exhaust don't do anything to change performance, why even change the exhaust. Im sure there are plenty of 1000hp cars running around on cast iron log manifolds.

I think your missunderstanding of how mechanics works shows here, hence why your opinion should not be taken on tuning.

I very explicitly stated there is no change to fuel/spark/incoming airflow by adding exhaust work.
This comment has nothing to do with 1000hp builds.
Exhaust flow simply “uncorks” the impeded flow coming out of the motor to allow it to breathe when more power is added.
Outgoing flow is not measured by any sensors, but incoming flow is. You tune incoming flow, not outgoing.

While exhaust work can make power in small amounts, your exhaust moreso supports power levels than making it within reason.

 

[HSKR R/T]

I think your missunderstanding of how mechanics works shows here, hence why your opinion should not be taken on tuning.

I very explicitly stated there is no change to fuel/spark/incoming airflow by adding exhaust work.
This comment has nothing to do with 1000hp builds.
Exhaust flow simply “uncorks” the impeded flow coming out of the motor to allow it to breathe when more power is added.
Outgoing flow is not measured by any sensors, but incoming flow is. You tune incoming flow, not outgoing.

While exhaust work can make power in small amounts, your exhaust moreso supports power levels than making it within reason.

So adding longtubes headers, which, as you just admitted, uncorks impeded flow of the crappy stock manifolds. The stock PCM can't necessarily compensate for that additional flow. The sensors may be able to read it, but it could be outside the "allowed" parameters of the tune.

Of course adding longtubes headers without any other supporting mods wouldnt be worth the expense of them