Hesitation and rough idle - sometimes

[rnelson]

My '98 with 150k miles started acting up the other day. It had all the symptoms of a bad fuel pressure regulator. It had the hard starting (that had been going on for a year or so), engine surges while stopped at a light, lack of power and hesitation while accelerating, etc. I did not have a fuel pressure gauge to check the fuel pressure. The part was cheap and easy to replace so I changed the FPR last night. The car ran perfect for about 10 miles and then started acting up again. This morning, while driving to work, it was 75% better than it was before. But, something is still not right. It starts right up now, idles a little rough at stoplights (unless I put it in park or neutral), and doesn't hesitate nearly as bad when I take off from a dead stop. There is no hesitation now when accelerating from say 50 to 60 mph. Any thoughts?

[ghutchin]

Sounds like a bad plug wire. You probably should do a tune up, plugs and wires.

[rnelson]

Someone I work with had suggested the plugs and wires. I have not looked at them yet. The only thing with that was I would think something wrong with a plug and/or wire would affect the engine all of the time. Also, why did things get 75% better by changing the FPR?

[ghutchin]

I thought you said it was idling rough at stop lights and having trouble accelerating. I assumed you meant all the time. When was the last time the plugs and wires were replaced and what were they replaced with?

[rnelson]

It does idle rough all of the time. It does hesitate on acceleration all of the time. But all of that smoothes out once the engine is not under a load and I am just cruising at a constant speed or I drop it into neutral or park. If it is missing and/or having spark issues, wouldn't it miss no matter what load the engine was under or what gear the car was in? The plugs and wires have not been changed recently. I will probably do that this weekend as well as a new air filter. Thanks.

[ghutchin]

no, it is much more likly to miss under load. Faulty wires are high resistance, or open circuit. Under light load the coils can fire, under heavy load they can not.

[rnelson]

I ended up replacing the plugs and wires this weekend. Not too hard of a job. This took care of my problem. Thanks.

[ghutchin]

Awesome!