I have a 99 5.4 F-150 that has a rough idle while at a stop. Happens in gear or out. I've brought it in and the dealer did code checks, fuel flow diagnostics, and injector checks and found nothing. Any one have any ideas. thanks

 

I have been having this same problem from day one with my truck. I noticed it the day I picked it up new from the dealer. I started with the dealer-- they CND (old Air Force term for "could not duplicate") the problem. I tried moving the wiring harnes away from the AC evaporator (or whatever that can-looking thing is)-- no help. Back to dealer -- CND again. -- Back again to dealer -they changed #3 coil (I think thats the #)--no help -- Back again -- they said they duplicated the problem once-- so they changed all of the plugs and did the engine balence thing (there is a TSB on this) -- NO HELP. I got to reading this board more and someone said that changing the "idle air-control sensor fixed their rough idle. I asked the dealer -- they put a new one in yesterday-- right now it's too soon to tell if it worked.
The main thing I have sensed about this problem is that the warmer the outside air is, the symptoms seem to show up less. In other words, the cooler it is the worse the problem gets

P.S. I have just under 12,000 miles on it

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99 F-150 XLT 4X4, SC, SB, AT, 5.4, Single CD
3.55LS, Tow pkg, Rhino Liner, Sportsman topper,
Westin black double step bars, Custom gold pinstripe, Bright Red/Gold

 

Thanks Markmizzou. Maybe we will get our trucks repaired soon. Keep me posted if anything new comes up.

 

Went all weekend -- did not notice any rough idle-- problem is that it has been hot and humid here, this is the kind of weather where the symptoms DON'T show up. -- I will keep u posted

 

Hey guys. I own a 1997 Expy and had the same problem. Except my check engine light would not go off. I read, read and read on this board and finally got some good advice from people on here. I did replace my O2 sensor on my driver side (Passenger was replaced just 2 months before)But, The biggest help was cleaning the MAS air flow sensor and the throttle body. I took the throttle body off and man was it nasty inside the plenum! I sprayed almost 2 cans of cleaner(Fuel injection cleaner mind you) and now the truck runs smooth as hell. The dealer did not even know what to do with it. So, the point is, do research the problem and be patient with people on here. You will get the asnwer to the problem.

Stephen

 

Don't you love this place? It's a repository of all possible fixes for practically any problem we have with our trucks. I hate to say this, but sometimes, we know more about our trucks than Ford does! I'm sure Ford will eventually put things together and figure out fixes for all the problems, but we just happen to do it much faster. I'd guess it's because we communicate better than they do.

I'd also have to blame the warranty repair system for being part of the problem. The way service departments gets paid by Ford makes lengthy diagnosis economically impractical, i.e., if it doesn't show up on the computer, it isn't broke.

 

This may or may not help, but just hopefully it can help SOMEONE. I have noticed most of your "rough idle" problems are w/ the 5.4 engine. I hooked up a scan tool to reclibrate the RPM's & Speedo after doing the white dash guage thing. I have the 4.6 Romeo, which has a slight non-smooth idle in gear or park. With the scan tool i checked the idle and it never varied more than 20 RPM's with the rough idle. My only question is we can not sit in each others truck and agree that this idle concern is the same. I'll say this much though, that after i installed the Flowmaster 17137, Duals out the back w/40 series the non-smooth idle was very non-existant! Could the reduced back pressure have any thing to do w/it? Spend $225.00 and you be the judge!!!!

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1997 F-150 LARIAT S/C 4x2 Styleside...Pacific Green Exterior/Silver Frost Accent...4.6L Triton (Romeo)...Auto...3.55 Limited Slip...Trailer Tow Pkg...Remote Entry w/ Anti-Theft...Power Everything...

FORD ACCESSORIES Wheel Locks...Molded Vinyl Floor Mats...Sill Plates (Look Great!)...Molded Mud Guards...

AFTERMARKET Deflecto Bedliner...Lund Bug Shield...Ventshield Side Louvers & Taillite Covers...A.R.E. Fibreglass Tonneau Cover...22 Piece Burl Wood Dash Kit...Custom Tweed Hood Insulator Pad...Westin Chrome Step Bars...

PERFORMANCE OPTIONS SVO Lightning Wheels w/ Yokohamo 285/50/18 AVS-ST Tires...Optima Battery...Evergreen F.I.P.G...Superchip YSL2...

STEREO Premium Ford Head Unit...Pac Lineout Convertors...Coustic 3E Crossover...JBL GTQ400 & GTQ200 Amps., Behind Full Functional Backseat...2x JL Audio10W4 Subs ...4 Pioneer 3-Way 6815's In Doors...

WHAT'S NEXT? Powerdyne Supercharger...Cat Back Exhaust...Roush Susp...Ground Effects...???...

 

Sounds good -- Boss Lariat -- but why should I have to install a new exaust for a problem that should not be there-??!!- I drove another brand new 150 and a used one with 23000 miles on it -- neither had this idle problem. They need (dealers) to keep on a problem till it gets fixed. My Dealer (California Ford-- in California MO) has been very helpful and willing to keep ******* my problem till it gets solved. I am hoping this Idle air sensor? fixes it -- I'll let you know as soon as it cools off here.

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99 F-150 XLT 4X4, SC, SB, AT, 5.4, Single CD
3.55LS, Tow pkg, Rhino Liner, Sportsman topper,
Westin black double step bars, Custom gold pinstripe, Bright Red/Gold

 

AGAIN THANKS EVERYONE FOR REPLYING. ALITTLE MORE KNOWLEDGE WILL MAKE OUR TRUCKS RUN BETTER. NOT SURE WHY SOME TRUCKS ROUGH IDLE AND SOME DONT AND WHY THEY ONES THAT DONT SEEM TO GET MUCH BETTER GAS MILEAGE BUT I THINK THEY ARE RELATED SOME HOW. MY TRUCK ROUGH IDLES AND I GET 12 TO 13 MPG AND A COWORKER HAS THE IDENTICAL TRUCK WITH NO ROUGH IDLE AND HE GETS 17 TO 18 MPG. AGAIN THANKS FOR THE INFO AND KEEP ME POSTED.

[This message has been edited by 36racin (edited 08-08-2000).]

 

36Racin, does your friend drive the same way you do and in the same areas? My mileage has not been anything to write home about either, but I sort of chalked it up to the fact that I live in this very hilly town with a lot of stop signs. I have still not noticed any rough idle since they put in a new idle air sensor thing? Trouble is, its still been hot here! The jury is still out as far as I am concerned!!

 

Be careful about spraying throttle body cleaner or fuel injection cleaner into your plenum. That stuff has a bad habbit of toasting your oxygen sensors once you restart the engine, as well as any other sensors it comes in contact with. I only know this because I cleaned the plenum on my 5.8 Bronco and it took out my air charge and oxygen sensor.

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Boss™

Just Ordered 2001 F-150 Lariat, Oxford White/Silver 4x4, medium graphite leather, SC, SB, SS, 99L 5.4L, 44E tran, 7700# payload, Class III Tow, 3.73LS, Skids, Capts chairs, 4W disc ABS, shift-on-fly, keyless, HD everything
Planned Mods:
"Protected by Smith&Wesson" sticker, Westin Chromed Stainless Nerf Bars, ARE LS II bed cover, Bedrug™, Gibson Swept Side Cat Back, K&N filter w/airbox mods, headers, Superchip, 3" body lift with at least 33's, alarm/pager/auto start system, stereo system

 

ACTUALLY MY FRIEND DRIVES ABOUT DOUBLE WHAT I DRIVE AND HIS FOOT IS VERY HEAVY. WE BOUGHT OUR TRUCKS ONE DAY APART AND HE HAS 23,OOO MILES ON HIS AND MINE ONLY 10,800 SO I STILL THINK IT HAS TO DO WITH THE ROUGH IDLE PROBLEM SINCE ITS ONLY REAL PROBLEM THAT I AM HAVING WITH MY TRUCK.

 

OK guys, check this out. My boss has a 98 F150 w/ the 5.4 that, according to him, has been running poorly. The symtoms were rough idle, jerky acceleration, and poor fuel economy. I relocated the harnesses away from the A/C condensor, unhooked the negative battery cable for 15 minutes, and look what happened! The difference in power and torque up to 4300 rpms was 26 hp / 50+ trq.....wow! The truck did however run acceptable above 4300, right where he never drives! Here is the kicker, the truck went back to being its old self after 8 dyno runs. What gives! Feel free to contact me if you want these graphs to present to your dealer or whomever. The check engine light DID come on, but I don't have a OBDII scan tool yet.






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2000 F-150 XLT Styleside

5.4, 4x4, Reg.Cab, 120" WB, White, Sport Pkg.

- Bell Tech lowering kit (3-4 drop)
- Gen II Lightning Wheels
- B'stone 285 60 18 tires
- Magnacharger S/C Kit
- Hi-Flo Intake Kit (my design)


dwh@dynojet.com

 

MORE GREAT INFORMATION. I WILL TRY IT AND GET BACK WITH THE RESULTS. AGAIN THANKS EVERYONE FOR THE GREAT INFORMATION!!

 

STILL HAVENT HAD TIME TO DISCONNECT THE BATTERY BUT WILL DO TODAY. SCHEDULED THE TRUCK TO BE IN THE SHOP AT THE END OF THE WEEK AND I NEED TO ATLEAST TRY IT OUT. AGAIN THANKS F0R ALL THE INFORMATION THAT YOU ALL ARE SENDING.