triguy74

Hey Guys,

Not much luck searching this on the forum. The first 5-7 minutes of driving my car I get a noticeable shake around 1700-1800rpm. This only happens in the morning and then it's fine the rest of the day. So I'd say it happens with the engine is "cold"...definitely not temperature related as I'm in SoCal.

I've replaced the plugs and coils and the problem remains. I'm thinking it might be something on the fuel side of things. Any thoughts/suggestions? Car has 115K on it.

Mud

Sounds like something related to open vs closed loop, meaning cold vs operating temp parameters in the computer. I've seen a failing O2 sensor cause a similar issue. Years ago I invested in an inexpensive OBD scan tool to at least point me in the general direction of issues and to see if any trouble codes were stored. Of course the dealer has much more advanced equip but you can still benefit from having a scan tool.
If the car is not progressively going from open to closed loop properly then the condition will be over-rich until all components are on the same page so to speak.
There have been shake issues related to failed engine/trans mounts but these happen whether cold or warm if I remember right.
Rather than throw parts at it I think even paying a shop to scan the car may be money well spent. If it were an injector or fuel pump then I would think you would have this condition when warm as well.

- Mover -

I would scan it as well. You may have some pending codes that will show up on the scan. These aren't serious enough to throw a check engine light but they do indicate something is wrong.

Is it like a cylinder a missing ?

triguy74

Thanks Mover and Mud. My neighbor is the service manager at a local Honda dealer and we went for a drive last night. He's certain it's an active misfire and that it's happening at higher RPMs as well, it's just less noticeable.

One of his techs used to work at a MB service dept so he plans to talk to him today and will also try to bring home a scanner to see what we can find. Like you Mover, he also said that it's likely it's not bad enough to give a check engine light, but there's definitely got to be some errors showing.

If we don't get anywhere with that, I'll just take it to my MB dealer and have them run a diagnosis and then we can start to sort it out.

Really appreciate the feedback. Never had this happen with a car before so I'm anxious/nervous to get to the bottom of it.