Dealer says my AFE Headers are causing rough idle

[ReLLIK75]

I started having an issue after installing a set of AFE shorty headers on my 2019 Rebel where it would start very rough after sitting over night in colder temps. It would sound like it was going to stall out (even would if I threw it in gear), but after about 20 to 30 seconds, things would settle down and the problem wouldn't occur again for the rest of the day. I thought it might be my Diablo tune, so I rolled back to stock and still had the same issue. I asked a similar question about this same behavior elsewhere and was told it might be the upstream O2 sensors--they won't throw a code; they're just bad. This doesn't make much sense to me and the dealer said that definitely shouldn't be the case.

I took it to the dealer and let them have it for 4 days. They were able to reproduce the issue twice and said it's definitely not the O2 sensors. They're blaming it on the headers. I talked to AFE and they said that the headers should not be causing that problem. I emailed Hemi Fever and he said there is no tune available to adjust the O2 sensors for the increased airflow caused by the headers. The dealer is suggesting I take the headers off and go back to my stock manifold. Sure I can do that--it's just going to cost another $800ish to have a shop do it. The main reason I put the headers on was due to my original manifolds being cracked and I wanted a permanent fix to the problem.

Has anyone experienced anything similar? If so how did you fix it?

 

[BowDown]

I'd find another tune then because that flat wrong, O2 sensors don't care about nor do they measure the airflow of the exhaust, its not a MAF.
O2 sensors don't need to be retuned due to an increase in airflow, your issue is most likely due to the O2 sensors not heating up fast enough when cold due to the headers and the placement of the O2 sensor either in the header or after the header.
Typically what you need to do is install heated O2 sensors in the front position when you install headers (rear O2 sensors are heated and what's usually used when adding headers).
Another option would be to pull the headers off and have them HPC coated which keeps the exhaust heat in the tube causing the exhaust retain heat and heat the O2 sensor. Another option would be wrapping the headers for the same reason but wraps are not as good as HPC coating. Easiest would be heated rear O2's in the front position.
A good tuner should have told you all of this when you described/ asked about the issue you're having

 

[ReLLIK75]

Tha

I'd find another tune then because that flat wrong, O2 sensors don't care about nor do they measure the airflow of the exhaust, its not a MAF.
O2 sensors don't need to be retuned due to an increase in airflow, your issue is most likely due to the O2 sensors not heating up fast enough when cold due to the headers and the placement of the O2 sensor either in the header or after the header.
Typically what you need to do is install heated O2 sensors in the front position when you install headers (rear O2 sensors are heated and what's usually used when adding headers).
Another option would be to pull the headers off and have them HPC coated which keeps the exhaust heat in the tube causing the exhaust retain heat and heat the O2 sensor. Another option would be wrapping the headers for the same reason but wraps are not as good as HPC coating. Easiest would be heated rear O2's in the front position.
A good tuner should have told you all of this when you described/ asked about the issue you're having

Thanks for the reply! Oh..i'm not blaming the tune or the tuner. My truck does this with the stock tune and the custom 91 tune. I'm just trying to get to the bottom of how to fix the issue. Been chatting with Jay Green and he also concurs that a tune will not fix the issue. Says that it's either my injectors or a software update. Back to a different dealer I go!

 

[BowDown]

I'm not saying blame the tuner for the tune, blame him for the lack of information. Thats basic and they should have been able to help you with that.
If it only did this after the header install, I'd bet your O2s aren't getting hot fast enough to measure unburnt fuel in the exhaust. This will cause the engine to run erratic until the PCM figures out what's happening with fueling which it seems to be doing once it gets warm.

If your truck was doing this prior to the header install, then yes, it may be an injector or software update issue. If this started after the header install, its the O2's.
A quick self test would be to let the engine cool then swap the rear O2's with the fronts then start and see if its still rough. The only issue you may have with that is the front are probably not heated and will not have the wire for needed to heat the O2. You'd need to figure out which rear O2 wire is for the O2 heater and jumper it to the front O2's.
Its a bit of work but I bet you beer thats where your problem is

 

[ReLLIK75]

I'm not saying blame the tuner for the tune, blame him for the lack of information. Thats basic and they should have been able to help you with that.
If it only did this after the header install, I'd bet your O2s aren't getting hot fast enough to measure unburnt fuel in the exhaust. This will cause the engine to run erratic until the PCM figures out what's happening with fueling which it seems to be doing once it gets warm.

If your truck was doing this prior to the header install, then yes, it may be an injector or software update issue. If this started after the header install, its the O2's.
A quick self test would be to let the engine cool then swap the rear O2's with the fronts then start and see if its still rough. The only issue you may have with that is the front are probably not heated and will not have the wire for needed to heat the O2. You'd need to figure out which rear O2 wire is for the O2 heater and jumper it to the front O2's.
Its a bit of work but I bet you beer thats where your problem is

Definitely started after the headers were installed. Although Jay Greene (Greene Racing) says it may be coincidental. So if I have to do some jumpering just to test, how would I go about actually fixing the problem? Buy a new set of downstreams, swap them in place of the current upstreams, and then run a permanent wire to provide power for heat? Might be worth just dumping the headers and going back to stock manifold covers.

 

[ReLLIK75]

So after a bit more research, it seams I that the downstreams are the downstreams and the upstreams are the upstreams...Swapping doesn't appear to be an option. How do I find an OEM heated upstream sensor for the 5th gen?

 

[BowDown]

Definitely started after the headers were installed. Although Jay Greene (Greene Racing) says it may be coincidental. So if I have to do some jumpering just to test, how would I go about actually fixing the problem? Buy a new set of downstreams, swap them in place of the current upstreams, and then run a permanent wire to provide power for heat? Might be worth just dumping the headers and going back to stock manifold covers.

You'd buy downstreams but youd have to likley put the upstream connector on them and jumper a wire from the heated rears to the fronts.
Another option I just thought of would be to move the O2 sensor bung to in front of the collector



But looking at that pic, your O2's should still be getting hot right there. Are you sure you didn't damage them?

 

[BowDown]

So after a bit more research, it seams I that the downstreams are the downstreams and the upstreams are the upstreams...Swapping doesn't appear to be an option. How do I find an OEM heated upstream sensor for the 5th gen?

Most front O2 aren't heated, that's why you'd need to buy rears

 

[BowDown]

Theres a guy in this thread that did the same mod as you and had the same issues, says it went away after the PCM relearned , few days of driving /cold starts

Hard cold start after header install

Hello, Any advice or ideas on this is greatly appreciated. Problem: Truck is hard to start on the first start of the day. This started occurring directly after installing my headers so I’m wondering if I did something during the install to cause this issue. It runs fine and starts up great...

5thgenrams.com

 

[BowDown]

When I put AFE longtubes on mine it seemed like the computer had to learn for a bit. It started a bit rough for maybe a couple of days, but had been perfect since then.
I put them on in June, no issues at all now.

Your truck sounds pretty good in that YT video!

 

[kapinallinen2]

According to this, all four O2 sensors are heated.

 

[Scarriere]

I should correct that post
I get a code sporadically. It can come on once is a few months and can come on several times in a week.
I can’t remember off hand what it is. Fuel/air mixture maybe? I took a picture of it and will confirm what it is.
I bought and OBD II reader that clears codes so do that when it comes on.

just to clarify, this is on my AFE longtubes.

I’ve had JBA shorties, the primaries are the same as the AFE shorties, on three previous Rams and never had a problem. Not a code ever.

 

[ReLLIK75]

So I successfully screwed up my truck today swapping out my upstreams O2s. Passenger side went fine, but I couldn't for the life of me get the driver's side wiring to disconnect. I inadvertently, pulled a little too hard and pulled the main harness four pins from the connector. It's such a tight area to work in and I've been unable to fully seat them back in the connector. I called around to a few repair shops and they said I probably broke the clips because the pins should easily go in and just lock in place.

Now I've got a CEL and had to order a new full engine harness at $400. Once that comes in, it'll probably be about 5 hours of labor to pull the old harness and replace with the new. Add another $800 for labor and, what should have been a simple O2 swap is now a $1200 repair.

 

[ekaz]

You should be able to just replace the connector, no?

 

[kapinallinen2]

You should be able to just replace the connector, no?

That`s what I was thinking.

 

[hellmans]

yep all 4 heated

 

[Jimmy07]

So I successfully screwed up my truck today swapping out my upstreams O2s. Passenger side went fine, but I couldn't for the life of me get the driver's side wiring to disconnect. I inadvertently, pulled a little too hard and pulled the main harness four pins from the connector. It's such a tight area to work in and I've been unable to fully seat them back in the connector. I called around to a few repair shops and they said I probably broke the clips because the pins should easily go in and just lock in place.

Now I've got a CEL and had to order a new full engine harness at $400. Once that comes in, it'll probably be about 5 hours of labor to pull the old harness and replace with the new. Add another $800 for labor and, what should have been a simple O2 swap is now a $1200 repair.

You can repair that. The connector shell is Molex 34899-4080

https://www.mouser.com/ProductDetail/Molex/34899-4080?qs=%2Fha2pyFaduirhTmDQr%252BBBSf31gSIX%2FALpomBUZb4mmVB9Qy7ph71Eg%3D%3D

The terminals are TE Connectivity 2177610-1

https://www.mouser.com/ProductDetail/TE-Connectivity/2177610-1?qs=%2Fha2pyFadui9o1SueRBFekQs82amVmInpCWdK5ARF1s%3D

 

[Scram1500]

It's not the headers, several people have the rough start/stalling phenomenon

ROUGH starts on cold starts?

Unfor unfortunately I see you have a tuner and 35's. When I went in to have them rescan for 34's, they said no way. I said they had no issue rescanning my jeep to larger tires for free. They said, it's not a jeep, sorry. I asked about using a tuner and they said unlike a jeep which they...

5thgenrams.com

Truck almost stalls out when cold start?

I have 32K miles on my 5.7hemi longhorn and recently I have been experiencing really rough idle when I start her up and my truck literally almost stalls out. after 20-30 sec idle smooths out and then runs fine. Anyone experiencing this as well? suggestions?

5thgenrams.com

 

[djevox]

The only thing I’m going to add to this is to stop going to the dealer to have them diagnose problems from aftermarket parts. Most of them are bad enough with stock OE systems.

 

[BowDown]

It's not the headers, several people have the rough start/stalling phenomenon

ROUGH starts on cold starts?

Unfor unfortunately I see you have a tuner and 35's. When I went in to have them rescan for 34's, they said no way. I said they had no issue rescanning my jeep to larger tires for free. They said, it's not a jeep, sorry. I asked about using a tuner and they said unlike a jeep which they...

5thgenrams.com

Truck almost stalls out when cold start?

I have 32K miles on my 5.7hemi longhorn and recently I have been experiencing really rough idle when I start her up and my truck literally almost stalls out. after 20-30 sec idle smooths out and then runs fine. Anyone experiencing this as well? suggestions?

5thgenrams.com

He didn't have the problem prior to installing the headers Seems like something happened to a sensor or wire harness during the install, that or it needs more drive cycles.