OK, I may be paranoid here and making nothing into something. Does this sound like rough idling to you? The past few days, the mornings here in the Northeast is a bit nippy with temps. in the 40-50 degree range.

When I first start the car, it idles around 1000-1100 RPM and subsequently goes down to 750 RPM after a few minutes, typcial of any car. But during the high RPM times there seems to be some rough "bumps" in the vibration pattern every 10-20 seconds. I know, I know, define rough. It'll be hard to do it in words.

I popped the hood and placed my hand on the top of the engine and just feel the cyclic vibration pattern and every 10-20 seconds there seems to be a hiccup or "discontinuity" in the pattern either due to a speed up or slow down of RPM or a piston sticking or hitting a burr. Of course I have not idea if any of those things are happening inside the engine, I doubt it they are. These hiccups are very faint but noticeable fror the feeling of my hand.

Here are some additional data points:

- I just crossed the 600 mile break-in period but we all know that the engine is still loosening up and there is no fine line between break-in and done periods. I wonder if this will go away as the miles add up.

- When I took delivery it had 265 miles on it already. Yeah, I know, not good but it was a previous swap from another dealer at an adjacent state and it was the last AWD with the right color and right accessories. So it was either that or no car and I need a new car ASAP. Who knows how those 265 miles were driven but I try to forget all the possible negative scenarios in my mind.

- Once RPM drops to 750 and engine is warmed up, it runs smooth as butter.

- At the higher RPM you can feel these blips on the steering wheel.

Now I may be blowing this out of proportion and I must admit, you really have to pay attention and don't move inside the car to really feel these blips.

My previous car which I just got rid of is a '97 Maxima with 270,000 care free miles and I don't think it did this (the blips) but to tell you the truth, I never paid attention to it back then. BTW, it's break-in period was 1000 miles with speeds no greater than 55 MPH as stated in the manual. It was a painful experience to drive it on the right lane!

Am I paranoid or overly sensitve?

 

This is very normal for honda/acura v6's. My dads 98 Accord V6, my old 01 Accord v6 and my 03 accord v6 all do it when warming up at higher rpm like you said. I own a detail shop as well and every honda/acura v6 I have started up after a detail(since the engine is cold) does the same thing. Don't sweat it bro!

 

If the engine drives fine, when you accelerate, your fine.

 

i have the same issue with my 04 TL, was told by the dealer the engine is purposely misfiring when its cold to quickly heat the cat'l converter. I assume this is how the engine gets it squeaky clean ULEV rating.

 

Thanks guys. Good to know about the known rough idle characterics of Honda/Acura motors. The engine drives fine, even when stopped at red lights, etc. Idles fine then as it's all nice and warm.

Purposely misfiring to warm up??? I've never heard of that one before! Wouldn't constant misfiring when the engine is cold damage the engine in a very short time span. I mean if we all go to work M-F, that's 5x a week that it misfires at a minimum.

 

I thought it was a weird explanation also.The tech at Acura assures me this is what's taking place and causing the lumpy idle when cold. With my TL approaching 70k trouble free miles cant really complain. Im sure the engine management is sophisticated enough to allow missfires without damage to the engine.

 

Yeah, that's what I was thinking. I figure if it was misfiring and it shouldn't have, today's sophisticated engine management system computer would have thrown a warning light/message somewhere on the dash.

I'm probably making a bigger deal than what is really is....

 

anybody have a cold start tick when started for the first time after sitting overnight?

 

thats 100% accurate...

especially the ULEV2 vehicles.... they dump TONS of gasoline in, to heat the cats up quickly.. so they act faster....

 

Interesting and that kind of make sense from some other data point that I've seen. I've noticed that during cold starts, the Avg. MPG drops about 0.1 after idling 5 mins or so. I did the same thing when the engine is warmed up and no drop in Avg. MPG. Conincidence?

I've seen this drop for the past 3 days. I'll observe some more.

 

What's a cold start tick? Like a blip in the vibration?

 

Sorry didn't mean to hijack this thread but a "tick" has no relation to vibration but when you first start the car after sitting overnight or prolonged time, listen to the engine and see if it makes a tick tick tick sound and sometimes people describes it as a faint knocking sound, kind of like the ones found in diesel engine but far less prominent.

 

No hijacking at all. Yes, I do hear the ticking noise but only when I pop the hood and stand in front. If you read my earlier post you see that I placed my hand on the engine to feel the vibrations. That was when I heard the ticking noise. The ticking didn't concern me as it sounded like valves tapping along.

It's probably normal due to the cold start, I think.

 

Slight ticking is normal even when the engine is warm. It may be amplified by the cold start but I assure you it is completely normal. Its valve tappet noise. As for rough idling, there are many reasons why this can occur which are all normal. The car could be attempting to complete onboard emmisions diagnostics, the car will do things like adjust the fuel trim to determine if the cat's and senors are all working correctly. Put it this way, if you didnt get a check engine light or a HIP message on the NAV you have nothing to worry about. As for misfires, the car does not misfire on purpose. Sounds like you may have some bad gas.

 

Thanks for the additional info. I now realize this is a non-issue as a few weeks ago I took my car in for service and they gave me a fully loaded RL as a loaner. Some "rough" idle and ticking noise. As a matter of fact, all noises generated by the RL in the cold sounded just like my TL in the cold.