Alright dudes, I bought a 2000 F150 4X4 with 78000 miles. I changed the plugs and one COP at 92000 miles. I have had two air filters in her since I took her over and I am about to put a K&N in her tonight. The truck has idled as smooth as the skin on my .... well, very smoothly. I have always run the regular old regular 87 octane fuel and mobile 1 synthetic oil in her.

By pure accident I filled her up with the high octane fuel about two weeks ago. I did not notice until she was already full. It was to late to switch I was stuck with a full tank of premium fuel. Three or four days and half a tank later I was taking the wife out for icecream. As we backed out of the drive way the motor sputtered due to thwe load of AC, power steering turned all the way to one side and brakes fully engaged. I put the truck in park and she popped right back to her normal idle. Those symptoms have not resurfaced.

A few days later I topped her off with regular old regular just like normal. Shortly after that the truck began idling poorly. It does not surge. It does not die. It does not hesitate. It DOES idle worse than I have ever experienced it before.There is no lack of power or lessened fuel efficiency. Just rough vibrating idle.

Should I replace COPs, the IAC, or the MAF? Everything is great except the idle. It still pulls like a sled dog and gets the same mileage as before. Should I leave her alone?

Sorry for

 

Haulin',

If you can find a solution PLEASE let me know! For a couple of years now my '97 LD F-250 5.4 would roll up to a traffic light and, if it was a long light, would slowly get rougher and rougher to a point. It would not stall or set any codes. Just enough to be annoying.

The probelm has now become severe. I finally had a light come on and took it to the dealer. The #1 COP was replaced and it ran great, for two days. Now its back to an intermittant VERY rough idle. It only happens if the truck has been driven for at least 30 minutes and is fully warmed up.

I love everything else about this truck! I bought it with 36K miles and now have 86K. All of my driving has been highway. It would be a shame to replace it now because of what MUST be an ignition problem. The t roughness almost always goes away as soon as I step on the gas but now its not doing that trick either. If I set the cruise control at 65 it will run all day and not miss a beat??!

Two COP's, the plugs and the fuel filter have all been replaced.

Anyone got any suggestions??

Jeff

 

I've read here and benn told elsewhere that all 8 COPs should be replaced at 100K miles. I've been told they start going around 90K sometimes last till 110K. I did buy and install a K&N air filter last night. I drove the truck to work this morning. It seem to run good. I'll let you know if it stops. I have been running cheap paper filters up to this point with no problem. The one I pulled out last night was dirty. It had dead bugs and lots of dust.

I'm not convinced that a dirty air filter could have cause my problem.

 

Far as I'm concerned, I've yet to see any info that says you need to replace the COP at XXXXXX miles. There are people with 200K mi + on the original COPs on this forum.

Sounds like you guys need to try cleaning your MAF sensor as a start. Then I would also look at the IAC valve....you could try cleaning it, but most times it is better just to replace it.

Before you guys just start tossing parts at it, I would take the rig down to the local parts house that reads codes (Checkers, Autozone, sometimes NAPA), and post them on this fourm.

Sometimes the symptoms that you guys describe come from plugged egr ports in the intake and such. You can do a search on that and find directions on how to clean them.

 

clean the therottle body and see what that does. but make sure you use a cleaner that is safe for coated therottle bodies. you also might want to get something to clean the MAF. i have a 1997 5.4 with 76,700 miles on it and it idels rough. i cleaned the therottle body one night but just did a quick one and niticed a big difference. i am going to take off and clean it really good. i have also noticed that it does not idel as rough when the weather is cooler out.

 

All,

Thanks for the suggestions. I just had the codes read when the dealer replaced to #1 COP. Evrything was reset at that point. No check engine light now. Can you have a code stored and no light??

I know if the problem vanishes and you do three trips,( I think ..) of some set duration, the light will go off but I guess at this point the code can still be stored?? At any rate no light at all since having the #1 COP replaced.

I had the the throttle body cleaned by Ford the last time a COP went out (that was #2 COP) at ~ 70K miles. That fixed another problem namely a sticky throttle plate.

I have not cleaned the MAF sensor. I do this all the time on my MR2 t, but thats for another forum! Any suggestions on how to do this on my truck. On the MR2 I use liberal amounts of solvents, works every time but I don't want to screw up something on the truck.


Thanks for the replies!

JD

 

spray the maf filament with electronic parts cleaner or you can also use brake kleen. Make sure the can says it dries without leaving a residue. i normally take my intake apart and soak the filament in a small bottle cap filled with cleaner but you can also spray it down without removing teh filament. this has worked for me since the truck (97 f150) was new and it has original maf with 173,000 miles.

 

Thanks, I replaced my paper filter with the K&N and cleaned the MAF with brake cleaner. She is idleing smoothly again.

 

if you bought the f&n filter that is oil soaked, probably pretty soon you will experience more idle problems i.e. dirty MAF. if you dont, great. if so then just clean the maf.

i took my stage 2 f&n off after about 20,000 miles and it sits in the garage. Truck ran better with f&n installed but i was not convinced it was filtering as well as say a puralator paper filter. Just my 2 cents.

 

Hi Haulinguser

If your truck is in all other respects running OK with no surge or visible tac variations dont play with it. I believe it is just a coincidence with the changing fuel thing. No harm done there. If you search this forum you will see plenty of others with the same problem. I have noticed some members saying that AIC of MAFF or PLUGS helped some but in almost all instances never fully fixed. If this rough idle is sorta like a vibration under your seat sometimes more or less get used to it sorry to say. I think it is the nature of the beast. I think Jimmy has said here he thinks it's a matter of agressive cam shaft timing together with lean mixture. I know mine started after about 9k right out of the blue and has been there since but runs wicked good.

John