My 04' TL seems to idle rough and almost seems like it's misfiring when I first start it up. Once it gets warmed up it seems to go away but I was just concerned that I might have a problem. I checked the Compression and it's around 180psi on all 6 cylinders. Is this normal for a TL?

 

When was the last time you changed your spark plugs?

 

noob question: how does it feel to have 'rough idle' or what's it like? 0.o

 

I've had the same problem. Pull out your air tube from the throttle body and look at the flap...is there alot of carbon build up? If there is, spray some carb. cleaner on a rag and clean it up nice. Your poor idle should go away.

 

If ur car is cold, or has been left sitting half the day it will be rough idle for atleast 5min until it warmed up.

 

Never changed my plugs before; the car only has 45k miles it shouldn't need plugs yet. The car just feels like it's misfiring when cold, you can feel it in the floorboard and steering wheel. The motor idles fine after about five minutes when it is warm. The guy at the dealer said it was normal and it had something to do with the ULEV system. I just wanted to verify.

 

the dealer is correct. The ULEV system will intentionally misfire to warm the cat's up faster to keep the environment happy.

 

yes what he said!

 

consult the owner book for all types of cold weather tips
Learn the abs -traction systems too- before you find them in an emergency~

here is the free book link- click year then model
move cursor to index and everything is there for you
https://techinfo.honda.com/rjanisis/...01_OMANUAL.asp

 

Mine does the same thing and the dealer gave me the same answer.

 

my car idles rough cold or warm. i can feel steering wheel, floorboard, even my seat shake. when im stopped at a light it vibrates and shakes and i can even hear a low rumbling noise. when im moving its ok. also....only when im in gear it does that. when i shift to park or N it suddenly quiets down and no more vibrations. WHAT CAN IT BE? CAN SOMEONE PLEASE HELP ME?!?!?

 

your issue is the motor mounts, one or more is broken. Take it to your local dealer to have them replaced under the warranty.

 

okay thanks. ill bring it in asap. is it bad that im driving it though? cuz i dont think i can get in for awhile

 

X2

Can you give more info on the intentional misfire when cold?

Mine does not do this, I have been paying special attention since this thread. It has a rock solid idle. FWIW, cold for me is a starting temp of 32F or higher. Maybe it's not necessary at these temps?

 

How do you go about finding out which motor mount is the culprit? I too have the cold start rough idle, but also have a minute amount of vibration otherwise. I understand the front (rear too?) is fluid filled, so that one should be easy to diagnose; but what about the rest?

I hate cars, do you post on bitog as BuickGN?

 

Yes sir.

 

Usually a car will idle at around 750 RPM's when turned on. the TL however idles at about 1000-1200 RPM when cold and misfires to generate extra heat in the exhaust system. this extra heat helps warm up the cats faster so they can reduce emmisions. The typical car takes about 6 miles of driving to warm up, I read somewhere that the TL w/the ULEV system takes about 3 miles of driving...

 

So I'm assuming it would intentionally misfire to get raw fuel into the cats for lightoff. I've heard the TL has to be in closed loop operation within 10 seconds of startup. It warms up faster than any car I've ever owned.

I'm just curious as to why mine doesn't misfire when cold. Maybe my temps aren't cold enough?

 

hm...i have the same issue, but i thought it was normal? could the motor mounts really be broken? can anyone chime in how to confirm? where to look, etc? thanks...

damn...i hope my mounts aren't broken!

 

...assuming you're within the 50k/4yr? or is under the powertrain one?

 

I suspect one of mine were broken since new. My car always had what I thought was a rough idle and I bought it new with 8 miles. Had the mounts replaced and you can't tell the engine is on when sitting at redlights.

 

Which ones were replaced? Which ones tend to be prone to failure in this car?

 

they must be broken then...i wonder how they could have broken?
is this under the normal warranty only?

 

Whenever my car is cold after sitting for a day in cold wheather i turn it on it sounds like a beast(V8), and u could feel so much low-end torque when hitting the gas just a little.

 

ulev system

 

Dam kinda old thread but mine feels like misfiring bad then after it warms up you can still feel it but not as bad. Is that normal too?

 

lol talk about a thread revival mr.ef8...your problem is definitely the motor mounts too. Take it into the dealer and have them diagnose. If you don't have a warranty then you should be able to fix them yourself. There are some DIY's here on the site that should help you.

 

Motor mounts won't cause a cold rough idle that disappears after 2 minutes or so.