thanks for the reply. i'll probably replace both o2 sensors this weekend, but before i do, i'm gonna hook my brother's 21 foot boat to my truck and drag it down the interstate. for some reason the truck goes into the rough idle more when its under load. last year when i towed my camper the light came on, but it went out a day or so latter. since then i've unhooked the battery to reset the pcm. hopefully i'll get a light, if not i'll spend $80 and replace the two o2 sensors just before the cats.

if anyone has any other ideas, please send them my way. thanks for all the responses.

 

I have a 97 4.6L I bought with 30k miles and it always had the intermittant rough idle problem you've described. Occasionally it would idle so rough I'd throw it in neutral (automatic) cuz I thought it would stall. Over the miles I've replaced plugs, wires, air filter, MAF (due to engine light and constant rough running), fuel filter and have used injector/valve cleaner every 5k miles. Nothing helped the occasional rough idle. About 5 or 6 weeks ago I hooked up the Superchips MicroTuner. The first time I took it out and stopped at a stop sign I had to check the tach to make sure it was still running cuz it was idleing soooo smooth. I'm not saying to go out and buy a MicroTuner but in my case I think it addressed some error in the FORD microcode. Maybe somebody else has had the same experience with an aftermarket chip? The microtuner cost me almost $300. Acceleration is much smoother, shift points are higher and firmer (that alone was worth the money), the increased power is very noticable. You do have to stick with 93 octain (even with the 93 I get a bit of pinging under heavy load, pedal floored, steep hill with 3.08s), but I've gained 1 mpg so the added cost per tank is only about $1.50. I don't tow so I'd check with someone who does tow and uses a chip before investing the money. Back to the point, I haven't experienced the rough idle since!

 

plug,

hey was just wondering if you had changed out your o2 sensors. and if you had, did it solve the rough idle? just let me know i am curious.........

 

haven't had a chance; my wife had quadroplets, but lost two of the babies, but two have survived and are in the NIC unit. so its been a very trying time the last couple of weeks.

i might get a chance to do it this weekend coming up. how many O2 sensors are there? one in front of each cat converters? one or two up by the headers?

 

Plug....so very sorry to hear about the two babies of your quadruplets. I sincerely hope the other two are doing well.

Changed my O2 sensors last week and had the usual difficult time just getting a wrench to them. Once changed, I noted a bit smoother throttle response, but it may have been attributed to the quick cleaning I gave to the throttle body. Overall, it still runs pretty much the same as before, which was pretty good...only a slightly rough idle at times.

Just last night I finished putting the electric fans in...too early to tell what kind of difference that made.

 

changed both o2 sensors. (piece of cake) 7/8" 0r 22mm open end.(special socket would not fit, too close to body.) driverside come up in between pipe and tranny. passenger side come in over frame rail behind front tire. used small tip flat screwdriver to hold clip in too disconect harness(too tight for both hands).

rough idle seamed to smooth out, idle stays up around 600-650rpm's. have'nt tripped it yet to see if the check engine light stays out.

 

plug,

i too am sorry to heard about the two babies that you and your wife lost. the two that are in nic i hope and pray they will be ok. when you get a chance to change them let me know if it helps any. kind of a small issue considering though...........take care and god bless

 

thanks for the prayers, we'll take all we can get. so far both babies are doing well. they're 24 weeks, so they are very premature, but they are in an awesome NIC unit. One is a boy, 1 lb 3oz, and the other a girl 1 lb 2 oz.

i actually climbed under the truck yesterday evening just to inspect the o2 sensors, the one on the passenger side before the cat converter(closest to the engine) is completely covered in rust and corrosion. it doesn't look too good.