Rep Power: 0

My 2001 Civic LX (automatic) has begun to sputter right after turning over. The car never fails to start, but sometimes it seems like it doesn't want to get going. It seems to have gotten worse over the last two weeks. No check engine light appears. The car just had a tuneup less than 10k miles ago. The records indicate that the throttle body was cleaned and spark plugs were replaced (among other things).

Description of the noise / sputter: Feels like a large, low rpm vibration which shakes the car (not violently, but noticeably) before it starts idling (idles fine); I assume this is the engine. It only occurs when the engine is cold. If I start the car shortly after driving it, it does not occur.

Hypothesis: The only ones I have thus far is that the fuel pump or relay is going though the car runs completely smooth on the road so perhaps I'm mistaken. It cal also be that the ignition module may not be supplying the correct voltage. It could also be that the fuel pump isn't getting the correct voltage upon start up, but I haven't verified this.

Action taken thus far: The only thing i've checked is the fuel pump relay (the blue one). It clicks when I power the car up though I'm not sure this is any guarantee that it's not damaged. I don't have a replacement to swap out but my sister has a 2000 LX and I may try and swap it with hers. There is a brown and black relay next to it... not sure what those are for; someone said the brown one is the master relay but it has one less plug than the blue one so I can't swap it. I do hear the fuel pump spinning briefly when the car is powered up. The car battery is nearly brand new and I had it tested (just to verify). It holds a full charge.

Any help is appreciated.

 
Rep Power: 313

Go buy some throttle body cleaner and clean your throttle body and sensors... 95% of the time this will fix any kind vibration caused by low idle. After you do that post the results, if it does not fix it we will look further

 
Rep Power: 0

"Feels like a large, low rpm vibration which shakes the car (not violently, but noticeably) before it starts idling (idles fine)"

There is no problem with the idle. It is exclusively a start issue. I should have mentioned that the car just had a tuneup less than 10k miles ago. The records indicate that the throttle body was cleaned and spark plugs were replaced (among other things).

 
Rep Power: 811

sounds like when i had a slow leak in the headgasket. coolant would drain into one or more cylinders when i shut off the car, then when i went to start it the next day cold, it would stumble and shake for maybe 10-15 secs but once the coolant burns off then everything drives like normal. once or twice i got the check engine light randomly and obviously the code was for cylinder misfire, which would explain the shaking if even one cylinder was not firing. also another way to tell is check the plugs. white residue = burnt coolant. also does your car lose any coolant? if it eats coolant slowly, you have a small headgasket leak that will eventually get worse and could blow the motor.

 
Rep Power: 0

Hi,

I checked the coolant levels, it still has within the acceptable range and the last time I filled it up was over a year ago so I'm guessing the coolant is not leaking. I also visually inspected the plugs, they seems to be in near new condition.

 
Rep Power: 811

hmm well our old accord has this problem too and its the main relay (the solder points are worn and messed so it acts funny and stumbles when you first start the car). i havent heard of this on a civic but its possible i guess. relays could cause alot of problems for sure if they get screwed up inside. you can open and check the solder joints to be sure. i dont know where the main relay is, but i do know there is a good collection behind the glove box. you could also have a small vacuum leak so check all the lines for rips. also this may be a longshot, but i remember on some 01 civics, the ecu had problems and there was a reflash to fix the rough idle on startup. i think theres a tsb for it here:

http://www.geocities.com/pfeifferperformance/TSBs.html