<TABLE id=post653607 class=tborder border=0 cellSpacing=0 cellPadding=6 width="100%" align=center><TBODY><TR vAlign=top><TD style="BORDER-RIGHT: #dddddd 1px solid" id=td_post_653607 class=alt1>hi, I have a 1998 f150 with almost 200,000 miles and it is powered by a 4.6 litre engine. About a month ago I was towing my boat and the check engine light came on. Didn't notice anything wrong with the way she was running other than the light was on. I never got the code read and I disconnected the battery to clear the code.
Last weekend, I was towing my boat again and near the end of my 60 mile trip the check engine light came on and it also started to flash. immediately the engine was running like crap. I pulled over and disconnected the battery thinking that I may reset something and my truck would start running better. I finished my trip with the engine constantly stalling and running poorly.
I took the truck to a garage but with the check engine light now off they could not diagnose it nor could they get the light to come back on, so I picked the truck up again and hooked up the boat and took off for a five minute ride and the light came on again but this time it was not flashing. So I dropped the truck off at the garage for the second day. They called me and told me that the code was for a lean fuel mixture but they could not figure out what was wrong. the mechanic suggested that it was not an individual cylinder problem and that I may have engine damage.
I took my truck back and I changed the fuel filter which seemed to make somewhat of a difference. I also cleaned the MAF sensor and changed the engine oil. The truck still idles rough but does not stall anymore and I can feel it running rough at higher speeds. the engine is the smoothest when I get to highway speed and then decelerate. I did complete my trip back with the trailer and the light has not been on since..
Anybody have any ideas?

Thanks
mike

 

You probably have a hole in the PCV tube elbow. Find the valve (in the middle of the passenger valve cover) and follow the tube to the back of the intake and feel the elbow. It may help to have the engine running so if you put your finger over the hole you can feel the vacuum. If it is the tube then first I would find a different mechanic b/c if he cant find a simple vac leak then he dont need to be turning wrenches, second go to the dealer and buy the tube and replace it. Shouldnt be more than 50 bucks.

 

You need to find a better shop. Any good shop can map the engine with a computer and see how the engine is running as a whole you should not have had to go back twice. It sounds like a vacuum leak or low fuel pressure.

 

mshastay, FYI, disconnecting the battery does not fix, repair or correct the problem. The only thing that accomlishes is clearing the codes and turning the CEL off.

The CEL comes on to notify you that there is a problem, and it leaves a code to be read. When the CEL flashes, that indicates that the problem is occuring NOW, as evidenced by the noticeably poor running engine.

The CEL being illuminated, does not cause a problem or make it worse, so there is no reason to clear it before the truck is repaired.

After 12 years + 200,000 miles, many of the rubber hoses under the hood should be replaced due to age and deterioration. The two hose pieces on each end of the PCV pipe are a common item, also the two elbows on the fresh air pipe to the drivers side valve cover, also the hose from the intake manifold to the emissions valve adjacent to the brake booster are all common hoses to be replaced at this time/mileage.
Good Luck