The car bogs down in varying patterns within the first 2 minutes of driving. It seems to be in conjunction with the warm-up sequence. I have noticed that it occurs right when my temp gauge starts to move. The severity of the sputtering fluctuates based on outside temp and duration of, and between drives. If I am driving hard to get somewhere quick, the next time I start the car (within a few hours) the bogging is at its worst. Other than the extreme loss of power and coughing the car shifts normally.
This behavior would, to me, seem consistent with a sticky valve of sorts. Initially it drives normally, but anywhere from 15-60 seconds in the sputtering begins and lasts for an additional 15-60 seconds. I cleaned the EGR ports just over a month ago, so I am looking for further diagnostic possibilities. Any ideas?

 

Does the check engine light come on at all? You can stop by an autozone and have them scan for codes. The connector is behind the ash tray.

When the engine warms up, the car uses the sensors to adjust the air/fuel ratio. A sensor may not be working properly. Have the sensors scanned using an OBD2 scanner to determine the problem. A faulty sensor should cause the check engine light to turn on.

 

Check the fast-idle thermo valve (FITV) #14. It's job is the fast-idle when the engine is cold. Maybe it's full of gunk & sticking??


Search on FITV for some threads about tightening something that commonly comes loose inside. Didn't happen to ME, so I have to be kinda vague.

Then #19 is the IACV, which also helps control the idle. That would screw up the idle after it's warmed up, but maybe it's dirty too?

 

Regarding the check engine light, it is on and has been since I've owned the car (18 months). However, when I first purchased the car this wasn't happening. I've had it scanned and its the manifold-side (upstream) sensor is said to be bad, and the result is a lean mixture.

It is only during that 15-60 second period that the sputtering happens. Once it clears the car runs like a champ, and doesn't reoccur until I start the car again.

 

A bad upstream O2 sensor fits your problem. When your car gets to operating temperature, the engine computer uses your O2 sensor among other things to adjust the air/fuel ratio.

If the O2 sensor is not putting out the proper signal, then the engine suffers. The computer will then use its presets to adjust the air/fuel ratio. The car will run rich.

Find out the specific code and post it on here.

 

I had my codes read at Advanced Auto and the print out they gave me said it was running a lean mix. This was some time ago and I don't have that paper anymore to quote the actual code. But if a bad upstream sensor compensates on the rich side would a lean reading be a reader error or an additional problem? I'll take it over to get read at autozone then to see if it says different.

 

The codes are in... P0170, P0171, and P0302. I don't know how the check engine registry works. For example, if in the case of the P0302 code, the number 2 cylinder misfired a couple times and the check engine light came on. Will it stay that way until I have the code cleared or would it be a constant problem keeping the light illuminated?

I ask because there is nothing noticeable in driving the car (audibly especially) that would lead me to believe there is a misfire.

 

I don't know how long before the lamp goes away by itself, but I think the code is stored longer. You can clear the code yourself by disconnecting the battery. Then IF it comes back you'll know it's not a one-time thing, or just stored from long ago.

Misfiring fits well with "lean" mixture, if you think of it this way... There's unburned fuel along with unused oxygen. But only the oxygen gets measured.

The sputtering would be the misfiring. Even if it only happens shortly after startup, it probably sets the code. Misfiring is more common than most people realize, & it's not easy to hear a single misfire. But it contributes to unburned HC emmissions, so the EPA requires the car to detect it.