2002 Taurus: Slightly rough idle, "push/pull" feeling

[sfontain]

2002 Taurus SES w/Vulcan, 35300mi.

FYI, I just bought this car used a couple weeks ago, and fortunately it's still in warranty, but I suspect the transmission hasn't had its 30K service yet (of course I am going to have that done within the next couple weeks given the mileage). The issue...

I notice that occasionally (but not always), when I am stopped at a red light the engine does not idle at a perfectly steady rpm--I can feel very subtle but rapid changes in the revs, sometimes enough to make the brake pads rub (you know, like that rubbing noise when you are just barely on the brakes enough to keep the car from moving in Drive). As well, sometimes when I am driving at speed (say, 40-50 mph, although I have not narrowed it down to that range at all), I feel a similar phenomenon--there is just a tiny bit of a "push/pull" feeling where the engine simply doesn't feel completely smooth. It's not a heavy jerk or misfire or anything, just quick, subtle changes in the speed of the engine/transmission. Any ideas?

Thanks!

[Madcat455]

Do you notice any changes on the RPM's on the tach???

[sfontain]

Originally Posted by Madcat455

Do you notice any changes on the RPM's on the tach???

Yes but <u>barely</u>, like maybe 50 or 100 rpm either way (which is why I question whether there is even a problem or if Tauruses just don't rev perfectly smoothly). It's only visible on the tach when stopped, though, because it's hard to observe these small changes when I'm driving since the tach will be moving around a little.

At driving speed, though, I can only feel the changes in the form of the light "push/pull" feeling I mentioned. In fact, yesterday, just once, from a dead stop at a light when I could see the tach moving and feel the revs slightly, there was some slight hesitation during acceleration.

I haven't linked this to weather, but yesterday it was abnormally warm outside for the season (about 60-65 deg. F.). When I experienced the hesitation in acceleration I mention above, the engine was still pretty warm from prior driving but had just been sitting in a parking lot for about 30 mins. while I was in a store. This morning in driving to work, it was about 30 degrees, and I noticed no trouble (but I'm not ready to assume the air temperature has much influence).

I am probably going to bring this to the dealer and complain since it's still in warranty, but if anyone has advice, I'm listening. Thanks!

[Madcat455]

LOL @ the dealer. Hopefully you'll get a good one.

My 03 Taurus has a prob like yours, only is when its in park, engine will just start jumping from 500 to 8-900 rpm's.... it'll be at normal idle(8-900), then just drop to 500... has stalled a few times too.

Had to a dealer 3 times, no luck finding the prob. They couldn't even get it to act up. I even left it there for a week once and still I'm stuck with the prob.

My car used to act funny when it was in gear too, I've noticed the Push/Pull thing with mine too, but only at like 30-35mph. HIgher speeds are fine.

Good Luck, It'll help the dealer if you know what conditions cause the prob (or was it all the time??). I'm just screwed I guess...lol.

[sfontain]

Originally Posted by Madcat455

Had to a dealer 3 times, no luck finding the prob. They couldn't even get it to act up. I even left it there for a week once and still I'm stuck with the prob.

Well... I'm not overly worried. Mostly I just want them to hook it up the computer and see if anything shows up. And I want a record that there is a problem now, BEFORE my car hits 36K, so if this turns into something significant later, I stand a chance of getting it covered by warranty because I brought it in early and they couldn't figure out what was wrong with it.

Anyone else?

[Willyum]

I had a variation in idle speed on my '02 on initial warm up. Service writer at Ford told me to change the fuel filter and come back if it still did it. Didn't have to go back.

[seidlebo]

I have a similar problem. It only happens at certain speeds, similar to yours. I also have the check engine light on... haven't had it diagnosed as of yet. I also find my daytime running lights pulse in time to the rough idle. I think it also happens when lights are turned on, but is barely noticeable. Since the check engine light is on, it would suggest something related to pollution components, such as the oxygen sensor, but since the lights are affected, it would seem to be electrical related.

So, don't have any solution... would be interested in knowing if your lights are affected.

[sfontain]

Originally Posted by seidlebo

I have a similar problem. It only happens at certain speeds, similar to yours. I also have the check engine light on... haven't had it diagnosed as of yet. I also find my daytime running lights pulse in time to the rough idle. I think it also happens when lights are turned on, but is barely noticeable. Since the check engine light is on, it would suggest something related to pollution components, such as the oxygen sensor, but since the lights are affected, it would seem to be electrical related.

So, don't have any solution... would be interested in knowing if your lights are affected.

I went to a dealer and they supposedly tested my IAC and found it was bad (I think they're full of BS) and replaced it at no charge. No improvement.

To follow up, I went to the dealer a second time and they couldn't find anything wrong, as I expected. This second time I got a nice, helpful service guy instead of the jerkface the first time. They did a small inspection of the vehicle this time, which was nice, and they reprogrammed my computer with an updated program.

In the end, the only "problem" I still have with this car is that the RPMs at idle will bobble 50-100RPM at seemingly random intervals. It's a very small change, and you just about have to be looking for it to notice it, but the engine does not maintain a perfectly consistent idle speed.

And I can't seem to break 20mpg with this car. I've changed the fuel filter, PCV valve, I just recently put in synthetic oil, had the ATF flushed, and the air filter is like new. I'm putting in new platinum plugs this weekend if the damn snow melts, but I was just expecting the mileage to be better. I have a 13-mile-each-way daily trip to work, and 11 of those miles are highway. Plus the car is rated 20mpg city, and I NEVER did worse than the rating in any other car. We'll see...

[seidlebo]

I have a Taurus wagon and have platinum plugs... haven't checked gas mileage, but most of mine is city travelling... and I know it is not that great. But, I have to believe this idling problem will reduce gas mileage, even if not always noticeable.

I've had the idling problem for over a year now, but other than an annoyance, hasn't caused any real problems. It has never actually stalled. Your comments on getting it checked-over are the reason I have never had a diagnostic performed. Don't know any garage that I trust enough and my past research on the internet has suggested the mechanics basically just start replacing one thing at a time. Can't afford it (or are too cheap), so will just put up with it. I do plan to start replacing some of the more obvious possibilities once it warms up and I can get access to used parts.

My problem appears to be not random... very noticeable at speeds around 30 miles/hr and 55 miles/hr. Cold hasn't seemed to affect it as seems to run the same in the winter and starts just fine even in -30 degrees Celsius (can you tell I'm from Canada? lol) I have a 120K km (75K miles) on my car. I didn't notice anything when I bought the car a couple of years ago, so can't say if it might get worse as you get more miles on it... but it's not likely to get better.

You didn't mention if it affected your lights... it is really noticeable with the daytime lights. My daytime lights weren't initially affected, but are now... leads me to think the problem may be getting worse as time progresses. Also, what is an IAC?

[sfontain]

Originally Posted by sfontain

I went to a dealer and they supposedly tested my IAC and found it was bad (I think they're full of BS) and replaced it at no charge. No improvement.

To follow up, I went to the dealer a second time and they couldn't find anything wrong, as I expected. This second time I got a nice, helpful service guy instead of the jerkface the first time. They did a small inspection of the vehicle this time, which was nice, and they reprogrammed my computer with an updated program.

In the end, the only "problem" I still have with this car is that the RPMs at idle will bobble 50-100RPM at seemingly random intervals. It's a very small change, and you just about have to be looking for it to notice it, but the engine does not maintain a perfectly consistent idle speed.

And I can't seem to break 20mpg with this car. I've changed the fuel filter, PCV valve, I just recently put in synthetic oil, had the ATF flushed, and the air filter is like new. I'm putting in new platinum plugs this weekend if the damn snow melts, but I was just expecting the mileage to be better. I have a 13-mile-each-way daily trip to work, and 11 of those miles are highway. Plus the car is rated 20mpg city, and I NEVER did worse than the rating in any other car. We'll see...

I've only had the car for a few weeks but it has just under 36K so I was lucky enough to have the work covered by warranty. I haven't noticed any dimming of lights or anything like that.

IAC is the Idle Air Control (Valve). It's attached in parallel to your throttle body. When your foot is off the gas pedal (i.e., at idle), your throttle plate is completely closed off to air so the engine couldn't run without some other source of oxygen. The IAC will open up to allow air into your engine so it can continue to run when you aren't accelerating.