Morning start "bog down"

[dr_greenthumb]

I am reaching 60K miles (58,000K, 2014 3.5 gas) and haven't done any other maintenance then routine oil & filters.

I started the car and the tachometer went up towards the 3 like normal but when coming back down dropped below the 1 and kinda "shuttered" if you will.

Do you think this is plug related, possible fuel or the dreaded vacuum lines?

I have plugs ready to go, please let me know what you think.

[feven1026]

does engine vibrate when it dropped below 1000 RPM on cold start?

mine did that, also, sounds like engine is trying to inhale and exhale

153K KM. 50I 14

[andrewmr]

If it only did that one time, I'd be tempted to just blow it off.

Put the plugs in and see if that has any impact.

[dr_greenthumb]

Originally Posted by feven1026

does engine vibrate when it dropped below 1000 RPM on cold start?

mine did that, also, sounds like engine is trying to inhale and exhale

153K KM. 50I 14

Yea, it was odd. I wasn't 100% paying attention as it was 6am and headed to work, all I really noticed was that it stuttered.

[dr_greenthumb]

Originally Posted by andrewmr

If it only did that one time, I'd be tempted to just blow it off.

Put the plugs in and see if that has any impact.

Yes, I believe it happened once or twice before, but barely noticeable to make it an issue. This time it was more prevalent to bring it up.

I think I will see what the plug change will entail, time, work, etc...

[kwstandard]

My 2015 3.5 started doing the same thing at about 48k miles. It was still under warranty, so I took it to the dealer... They said a software update fixed it. No parts required. Has not done it since.

[feven1026]

Originally Posted by kwstandard

My 2015 3.5 started doing the same thing at about 48k miles. It was still under warranty, so I took it to the dealer... They said a software update fixed it. No parts required. Has not done it since.

does it improve on cold starting? like noticeable difference

[PeteyF15]

I have this same issue
Vehicle will randomly on start up, not based on outside temp or engine temp do this rpm rev up.
Then shutter and bog and shake then level out and all is fine
I get a pretty crazy vibration idling sometimes as well that you can feel through the steering wheel. Any help appreciated. Might just take to dealer for a software upgrade

[P1]

In mine, it ended up being an injector that was on its way out. It eventually did go out, had it towed and fixed. Hasn’t done what you describe above since.

[1norseman]

35i, 50i, ??
First time I had a similar issue, it was the crankcase vent hose. Second time an injector starting to go bad.

[dr_greenthumb]

I am not sure, after further research it appears to be a common, misunderstood phenomenon with these vehicles. Sometimes the issue may be something more severe and problematic, and then sometimes possible a gas issue, bubble in the fuel line... I have had vacuum line problems with my older 04 528 I had, but the issue didn't come and go, that is what I am pondering.

The issue didn't happen this morning, or yesterday afternoon leaving the office...
One of the threads I read is when these vehicles are woke up from their "sleep" they prime the fuel lines. Some stated that this procedure may have been the issue, that the priming wasn't fully established, or a second or two may have helped it out?

[kwstandard]

Originally Posted by feven1026

does it improve on cold starting? like noticeable difference

I only had the issue on cold starts before the claimed software fix. Has not done it at all since the repair.

[dr_greenthumb]

This same problem seems to be getting a little worse as the temperatures cool down. The plug change last year didn't seem to help the problem, from all the research I have done (not much out there with this issue) it's really not exactly known what the issue could be. From reprogramming, injector, plug, coils, vacuum leak. I would think the vacuum leak would be prominent when the motor is warmed and running too, not just cold start. I had a couple codes but no good leads to this problem.

Could I check the injectors when the engine is running with my Foxwell scanner, or possibly have the motor running and check certain parameters that could lead to an issue. Or have the Foxwell connected and on for an early morning start?


EDIT: I am going to try Chevron Techron Fuel injector cleaner first
2nd replace the coils with new plugs
3rd try and narrow down "if" it's a certain injector

[dr_greenthumb]

I just now got one full tank through with the Techron Complete cleaner.

The "bog down" issue seemed to be gone, but then it did it once briefly, but not as bad.
That was about half way through the tank with cleaner in it.

I have one additional bottle of snake oil Techron cleaner, not the "complete" cleaner bottle, but it's made for a 1/2 tank of gas, seems as a half clean. Instructions: Add the entire bottle and fill to 12 gallons. I'll run this through and report back.

[F15_SGM]

Originally Posted by dr_greenthumb

I just now got one full tank through with the Techron Complete cleaner.

The "bog down" issue seemed to be gone, but then it did it once briefly, but not as bad.
That was about half way through the tank with cleaner in it.

I have one additional bottle of snake oil Techron cleaner, not the "complete" cleaner bottle, but it's made for a 1/2 tank of gas, seems as a half clean. Instructions: Add the entire bottle and fill to 12 gallons. I'll run this through and report back.

I wouldn't put any of those cleaners in my car. Last time I used something like that on an old car it broke. When did this issue start? It's been cold in Oklahoma recently. It might be an injector. If so just buy the part that way you don't have it happen randomly especially when you need to go somewhere. A video of this issue might help in understanding what it is. Also if you are in the OKC area my mechanic is Ferrari tech certified, very honest, and affordable. He is the best in the state.

[jsbaker]

I was having the same problem every day the first time I started the car no matter the outside temp. I ran a can of the Liqui Moly injector cleaner through the tank and it hasn't done it since. Of course now it will likely start doing it again tomorrow morning.

[dr_greenthumb]

Originally Posted by jsbaker

I was having the same problem every day the first time I started the car no matter the outside temp. I ran a can of the Liqui Moly injector cleaner through the tank and it hasn't done it since. Of course now it will likely start doing it again tomorrow morning.

The Techron helped, but didn't fully mitigate the issue.

Originally Posted by osmansiddiqui95

I wouldn't put any of those cleaners in my car. Last time I used something like that on an old car it broke. When did this issue start? It's been cold in Oklahoma recently. It might be an injector. If so just buy the part that way you don't have it happen randomly especially when you need to go somewhere. A video of this issue might help in understanding what it is. Also if you are in the OKC area my mechanic is Ferrari tech certified, very honest, and affordable. He is the best in the state.

Where is the guy located, shop name?

[F15_SGM]

Originally Posted by dr_greenthumb

The Techron helped, but didn't fully mitigate the issue.



Where is the guy located, shop name?

It's called Executive Garage Located in Oklahoma City. Owner/Tech is MJ. He is very trained in our vehicles.

[dr_greenthumb]

RPM dance happened again this morning, I really think the injector cleaner helps, but didn't fully mitigate the issue. (I say this bc the issue was everyday, now it's only random)

Can the FOXWELL scan tool help me to diagnose / check the injectors?

[tlow98]

Injector cleaner helped my 35i on cold starts as well.

Does this mean one day we’ll need injectors?

[Megatr0n]

Originally Posted by P1

In mine, it ended up being an injector that was on its way out. It eventually did go out, had it towed and fixed. Hasn't done what you describe above since.

+1 I would change the injectors and while you add it just change the coils and the spark plugs if you haven't done so. They are all pretty easy to change if you do it yourself.

[devlinsky]

Originally Posted by tlow98

Injector cleaner helped my 35i on cold starts as well.

Does this mean one day we’ll need injectors?

Most likely. That was my case. Along with oxygen sensors etc.