Slight rough idle

[06wing]

Picked up a '98 2.5l a few months ago with about 100k on the clock. Although it is in great shape and seems to run well at highway speeds, after it warms up for a few minutes the idle seems a bit rough. Doesn't seem like it wants to stall, but vibrates enough to notice, especially if the a/c is on. Wondering if you guys have any suggestions on where to start, no history as far as maintenance. Went ahead and changed oil and flushed cooling system when I bought it, but no tune up, etc.

Thanks,
Brian

 

[gfxbss]

My '98 2.5L was idling quite rough for a while. Could be a number of things. That being said, when I changed the fuel pump, my problems w/ a rough idle went away.

 

[BT2413]

I would start with general tune-up stuff first

 

[gfxbss]

I'm not saying to start by dropping the tank, by any means. That being said, I would check the fuel pressure at the rail. Along w/ tune up stuff.

 

[Rackster]

Tune up time

I agree with the other members - probably time for a tuneup. The plugs and wires on your truck are meant to be changed at 100K. That said, there is plenty of data out there that suggests that the plugs should be replaced sooner than the 100K interval that was specified by Ford. When I removed my original plugs at 94K, the outer electrode had eroded some .010-.020". I didn't see a loss in MPGs or power, but the fresh set did seem to make the engine more spirited. I think I might have actually lost an MPG or two on the change. I'm not sure why that might be (properly gapped and new wires too), but it was suggested that if I didn't put the wires back into the harnesses exactly the same way, you could end up fighting EMI gremlins. So be mindful of the wiring when you go to do the tune-up. Also, it may be necessary to remove the intake manifold for doing the driverside plugs. I got away without having to do that, but it is a bear!! It will slow things down nonetheless.

Good luck!!

Kevin