Hi, I have a 2019 Ram 1500 Rebel with the 5.7 Hemi. It's at 61,000 miles, owned it since new and have changed the oil every 7,000 miles. For a few thousand miles it has been having an issue on cold start that was barely noticeable but now has begun to get a lot worse and very noticeable. When I start the truck on cold start only, doesn't matter if it is with remote start or from within the truck, it will start like normal, then after a few seconds will begin idling really rough and sound like it is going to cut off. Then a few seconds after that it's almost like the computer is compensating or something and the RPM comes up to fast idle and then will slowly idle down to normal. It runs smooth after the cold start and I have noticed no driving issues and no issues on a warm start. The choppy/rough idle on cold start is just getting worse (but also depends on the day as to how bad it is, some days worse than others). I expect the increase in RPMs when starting, but not the rough idle part.
I checked the air filter and it is clean, I pulled the tube from the air filter box to the throttle body and the throttle body flap is shiny clean. I thought about pulling a spark plug to check it but didn't because I figured if it was a spark plug issue that it would idle bad all of the time instead of just cold start.
Could this be oxygen sensors or mass airflow sensors or something else entirely?
Thanks!
Could this be oxygen sensors or mass airflow sensors
I think there's a good chance, you'll need a scanner to see where bad data may be coming from. It almost sounds like an O2 sensor that isn't heating up properly, thus giving bad data to the computer when the exhaust system is cool (I think this usually trips a CEL).
Do you have a check engine light with any trouble codes?
That makes sense about the potential O2 sensor. I’m going to ask around and see if I have a buddy with a good scanner to check it out with me.
I don’t have any check engine lights and I went to have autozone scan it and they said they can’t scan it without a check engine code, I’m not sure if that’s true or not.
Could be all of the above. Spark plugs are on the list and are probably due to be changed if you never have. It’s a hassle because you have 16 of them. But even if they aren’t the culprit, inspecting them often gives you useful clues.
Welcome new member!
Thank you! I ended up pulling a few of the plugs this evening to check them and they look great. I was looking around for the replacement interval and it’s amazing how many different mileage recommendations are out there. I’ve seen 30k and 65k but the Ram maintenance interval recommends 100k. I laughed out loud when I saw one Ram dealership recommended every 10k miles though lol.
I’m definitely not looking forward to changing them when it’s time though because of how bad the access is.
Every 10k, seriously? LOL
Could be a dirty or failing idle air control (IAC) valve.
