Rough then smooth(ish) idle after startup

[Jeepmonster]

I've had similar issue with rough idle- felt like engine was shuddering or stumbling after settling down to 600-700 rpm after a cold start. Never got a code. Always went away once warmed up. I've checked belt, belt tensioner, engine mounts, etc.

On the advice of a Youtube video, I removed the throttlebody, and cleaned the edges of the throttle blade and the inner surface of the throttle body. There was a slight build up on both surfaces. After cleaning it, I haven't had the issue occur again. Only been a week, but that seems to have fixed it.

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[WILDHOBO]

I've had similar issue with rough idle- felt like engine was shuddering or stumbling after settling down to 600-700 rpm after a cold start. Never got a code. Always went away once warmed up. I've checked belt, belt tensioner, engine mounts, etc.

On the advice of a Youtube video, I removed the throttlebody, and cleaned the edges of the throttle blade and the inner surface of the throttle body. There was a slight build up on both surfaces. After cleaning it, I haven't had the issue occur again. Only been a week, but that seems to have fixed it.

I like it. Thanks. Any pictures of it before you cleaned it up?

 

[Jeepmonster]

Here's a picture, but I had already wiped a good amount off before I removed the throttle body. You can still see some dark build up on the upper and lower edges of the blade as well as the surrounding area. It was getting dark, so I had to hustle.

 

[Jeepmonster]

The oil mist comes from the breather tube just right after the air filter box. It doesn't take much to get the throttle body dirty. Below is a picture of the stock throttle body next to the new one I put in (about the time I installed the Mopar CAI kit). You can see some build up on the stock one (left) when it had about 8k miles on it. The one I replaced it with is one from MMX (Modern Muscle Xtreme). It's a factory part with material removed for better flow. With the CAI, it did make a noticeable difference.

 

[yoda13]

I have this same problem. The dealer said it would likely result in engine failure and that I should drive it hard, but expect nothing to be done about it, until it fails, and I’m stuck on the road somewhere.

I think I’d try a different dealer…although that, admittedly, has not gotten me anywhere.

 

[WILDHOBO]

Here's a picture, but I had already wiped a good amount off before I removed the throttle body. You can still see some dark build up on the upper and lower edges of the blade as well as the surrounding area. It was getting dark, so I had to hustle.

Mine is definitely worse than yours in that picture. Golden brown tarnish sound like what yours was?

 

[WILDHOBO]

Mine is definitely worse than yours in that picture. Golden brown tarnish sound like what yours was?

This isn’t a straight on picture, and is from August 12th, but it’s somewhat visible. I’m assuming you used carb clean, @Jeepmonster?

 

[Jeepmonster]

This isn’t a straight on picture, and is from August 12th, but it’s somewhat visible. I’m assuming you used carb clean, @Jeepmonster?

I had some dark brown (like oil tarnish) that came off with wiping, but I had to use the cleaner to get the black caked on stuff off. This is what I picked up from a local O'Reilly.

 

[Jeepmonster]

@WILDHOBO , if you decide to clean yours, make sure you remove the throttle body to clean the discharge side as well. I had some build up on both sides.

 

[WILDHOBO]

@WILDHOBO , if you decide to clean yours, make sure you remove the throttle body to clean the discharge side as well. I had some build up on both sides.

I definitely will. I way to remove. Thanks. I love little maintenance projects like this.

 

[Thinback]

I had a 86 ford ranger 4x4 2.9 v6. I had to clean the throttle body every so often. Gum cutter and a tooth brush would fix it right up. It had a throttle body by pass as well. I would take that off turn it on its side and soak it. After that the idle would be back to normal. I never had to do it to any of the other gas trucks I owned going forward.

 

[KevinM60]

The dealer replaced my engine under warranty because of metal in the oil.
At around 2k miles my new engine developed the cold start rough idle. Once it warms up it goes away.

Today I ran the OBD2 on it and in the advanced DTC section I found the P0007 code.

I have already made an appointment with the dealer service before I ran this test and I’ll take it to them and let them fix it.

 

[Random Exits]

2020 JTR V6 81,000 miles. Researching I found that there is a TSB regarding the camshaft which may be the rough idle issue. My 2020 JTR was throwing a Cyld 3 misfire so the mechanic replaced the coil. still idles rough but no CEL. Also saw it could be a vacuum or spark plug issue. Both were ruled out for me so I am going to hit up the Jeep shop for cam shaft.
Also, found a bulletin on JT instrument clusters erroneously illuminating caution lights. Think there also a TSB on that.

 

[KevinM60]

The dealer inspection on mine showed everything to be okay. Their equipment didn’t find the P0007. The rough idle is pretty slight and they said that was normal. I figured I would go with it and since I had them check it out I am covered on warranty in case anything bad does develop.

 

[NonHyphenated American]

@WILDHOBO , if you decide to clean yours, make sure you remove the throttle body to clean the discharge side as well. I had some build up on both sides.

Did you disconnect your battery when you took off the throttle body or is just disconnecting the wiring good enough?

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