i got a 98 f-250 xlt light duty, just had its 100,000 mile tune-up/overhaul now the check engine light is on and i need a complete list of codes

 

Hi and welcome. I don't have a complete list that I can post, but if you post your codes, I can tell you what they are and what it will probably take to fix it.

 

i got the left bank and right bank too lean..... i flushed the fuel system out and it still idles all jacked up.....? i put a new fuel filter in it also but when it idles down to 700 it starts to chug and the rpms drop to like 5 then kick to about 1500 then back down again. i also just put new plugs in it the bosch platnum+4s maybe thats whats messing with the chi of my truck

 

Could be, I would check for a vacuum leak first. Especially the PCV hose behind the throttlebody on the intake. They are known to crack and cause a vacuum leak. Also, make sure that the air intake tube between the throttlebody and the air cleaner housing is sealed good. A vacuum leak will mess with the MAF readings. I would also go ahead and clean the IAC. It could be sticking, but it sounds more like a vacuum leak.

 

yeah i thought pcv too and changed it the check engine light went away but it still runs like awful. Now it just stalls when the rpms drop I also took my cold air intake kit off and the throttle body has quite abit of carbon in it. I tightened all the clamps and and supports going in and it still didn't make a difference. How about the fuel pressure regulator? since both banks popped for running lean? Maybe the fuel pressure drops to low at idle and its constantly adjusting? cause it will idle at 900 till it warms up then drops down to about 600 then it starts to fluctuate.

 

There are lot's of posts about folks having problems when they switch to bosch plugs on these mod motors. Quite often switching back to Motorcraft or Autolite Dbl.Plats. will resolve. Regrettably it's a "PIA" to change the plugs the first time, much less twice on the same tune-up!

Hopw this may be of some value...good luck.

 

yeah i found out this week there is a tech bulletin out about using bosch plug in modular motors........ford says bad ju ju so im headed back out this weekend for a swear fest in plug changing on the 5.4l to see if this is the problem thanks all for the help

 

Did you try to clean the IAC? Those will cause a bad idle.

 

Illl take a look, the plug change did nothing but cost me more money i checked ll the air connections coming in to the mass air sensor no leaks

 

I have the same thing going on with my truck. I have a '97 F-150 4x4 with the 5.4, has 98,800 miles. #1 and #2 banks, codes 171 & 174, lean condition. I've change the spark plugs with Autolites Dbl. Plat., added fuel injector cleaner, checked for vacuum leaks, cleaned the MAS, changed two O2 sensors (LT & RT, forward of the CAT). My question is...Could it be the Idle Air Control Valve? A few friends has told me that could be it. Haven't seen anything here in the forums though. I've already spent $160 on plugs and sensors. Please help!

 

I wrote earlier today with the same problem and I fixed it! I took LxMan1 advice..."I would check for a vacuum leak first. Especially the PCV hose behind the throttlebody on the intake." I checked the hose yesterday with the engine running and couldn't feel a leak. I decide to look at it one more time before taking it in to the dealership and I pulled the PVC hose off and sure enough it had a rip in the 90 degree elbow at the back side of the throttlebody. Check this out! Save your money! Thanks LxMan1!

 

Glad to help

 

yeah i tried that first Im at the point with the IAC or O2 sensors ive done everything else....i still refuse to take it to the dealer though....my labor is free