1999 Explorer 302(5.0) w/AT

Back in June, my check engine light came on and the engine started to run rough. (High Idle, Loss of Power, Engine & Exhaust tone louder, Misfire)

Had a Ford dealer scan the computer, culprit was #4 spark. So I changed all 8 plugs (Motorcraft Double Platinum, all 8 Wires (Motorcraft 8 gauge), PCV, & Fuel Filter.

Still my truck has a rough idle (varies), lack of power (most noticable on any form of incline) but still present when not on an incline, drop in gas mileage from 15.5mpg to 13mpg, sluggish response when accelerating, engine & exhaust tone louder than before, problem gets worse as the engine warms up, have to press accelerator hard and down farther than usual for response, sometimes it takes an extra 3-4 seconds to start, after each shift point the truck loses alot of power and seems like it bogs down, but the check engine light has not come back on again.

Since the original diagnosis, I have taken the truck back to Ford, and to two independent auto shops. I was informed by Ford and one independent shop that they could not find anything wrong. The other shop stated it was the IAC & Fuel Pressure Regulator/Damper. So the IAC & Fuel Pressure Regulator/Damper were swapped out, but I still have the problem.

Here is a list of parts I have cleaned or swapped out, which have not helped much. all 8 Plugs & Wires, Fuel Filter, PCV, all 4 O2 sensors, IAC, Fuel Pressure Regulator/Damper and I have cleaned the MAF Sensor. Currently I have a TPS on the way from Ford, hoping this may help.

I'd hate to take the truck back in for another diagnosis, since I have already paid over $300 in diagnosis fee's and the problem is not fixed.

Any and all suggestions would help, and will be looked into. No one can seem to find the problem, including myself.

Thanks in advance for the help and ideas.

 

Ok if you had a misfiring plug you were sending fuel down the exhaust pipes. Drop the exhaust pipe in front of the cat and look inside to see if it still looks like a honeycomb in there. Chances are you melted the honeycomb and have a plugged cat. I had this happen to me a long time ago. Sounds exactly like you describe it. Worse thing you may have to replace is the clamp or a seal. Personally I would just use a hollow pipe to remove (comes out very easily with a little ramming) the melted area and then hook a shop vac to the end of the hollow pipe and suck the broken pieces out. This way you still have some cat left vise having to but a whole new cat.

 

Thanks for the advice.

Unfortunatly, I suggested this to the Ford Dealer & one of the independent auto shops. To make sure they checked this out. Both stated that the back pressure/flow was at the recommended specs. Also, the truck only has 58K miles on it, so the Cat would be warrentied if it was bad. Evidently Cat's (model year 1999 and up) have warrenties covering them for 7 years or 75K miles. So I don't believe this is the problem area. Anything else you may think of would be helpful.

 

WELL YOU KNOW A DEALER IS A DEALER IF SOMETHING IS UNDER WARRANTY YOU KNOW THEY DONT WANT TO PAY FOR IT SO I WOULD TAKE THE ADVICE YOU GET HERE FROM GUYS WHO REALLY WANT TO HELP YOU RATHER THAN GUYS WHO DONT WANT TO WORK FOR FREE IT SOUNDS EASY TO DO AND IF IT WERE ME AFTER YOU SPENT ALL THAT TIME AND MONEY GETTING DIAGNOSTICS YOU SHOULD GIVE IT A TRY IT CANT TAKE THAT LONG AND HE SAID ITS JUST LIKE HE HAD HAPPEN SO THERE IS A GOOD CHANCE IT MIGHT BE IT. GOOD LUCK

 

Replaced the EGR Valve, and the power is back. Only thing is while warming up and driving it will slightly shudder for a moment. This only happens on light acceleration from a stop at the 2nd or 3rd stop of the day. After it's warmed up, there seem to be no problems. It will idle high (about 1000-1200RPMs)when cold, but once warm the idle goes back to normal. Any suggestions?

Thanks again for all the help!