02 Sport Trac Engine problem..

[Rock99and9]

Have an 02 Sport Trac with no mods, 64,000 miles. Couple of weeks ago, my wife was driving it and the "check fuel cap" light came on. She had just filled it up and the cap was loose. She tightened it and drove home. That light went out but the CEL came on before the fuel light went out. The next day while driving in town, the engine starting surging and dropping to 500 rpm while at stop signs or idling. The Trac ran fine at speed then as it does now. Only time problem occurs is when idling at stop signs or lights, or when engine speed drops below 1000 rpm.

We've taken it to two different Autozones, neither could read the code(s) came back as an error or nothing to show. The CEL remains on and the idle is still off.

Have cleaned the MAS, The IAC, and the EGR Valves. The engine shut off when the IAC was disconnected. Was able to keep it running if the throttle was given gas after IAC was disconnected. Disconnected the MAS, the engine idle went up for a few seconds then dropped low and died.

Has a brand new air filter, changed the plugs, (Although 2 and 3 are a pain in the "you know what" to even see let alone change. No change.

The dealer, Ford where we bought the truck wants $95 just to read the code(s).

The only "cure" I've been able to live with is to left foot brake when coming to signs, lights or when the engine is idling, using the right to keep the engine speed up and stopping the surging.

I've read the forum for a few hours tonight and have tried numerous suggestions as to what could be problems from what could be similar problems.

Just wondering if anyone had any other ideas? I did disconnect the neg bat cable after cleaning the three parts mentioned above, reconnected and drove the truck approx 20 miles, 30+ minutes at speed and in town. the problem seemed to be gone till I arrived at the drive way, the CEL light came back on and the engine started surging and dropping to 500 RPM's again...

Thanks for any thoughts or advice!!

 

[gguerra]

I have the same problem on a Mercury Sable I have.. I am no expert mechanic but just to take guess at it I would check the idle speed control valve and/or O2 sensors.. Try this site for more expert advice, this is a ford thing and not a sport trac thing.. http://www.2carpros.com/makes/ford/ or google it for many more possible sites/solutions

 

[Rock99and9]

Thanks I'll give the site a try. Did clean out the Idle control valve, was pretty dirty before. Didn't seem to help. A friend who has worked on Explorers before today suggested the Idle Air control Valve solenoid? Will have to look that one up.

Just hate to start replacing $30-$80 parts that could be the problem only to finally figure out which one the problem part is. Have no problem replacing the plugs as the originals needed replacing anyway.

One thing my wife and I did figure out last night after posting this, when the engine is cool, the problem is not there. It starts once the temp gets to normal range.

Thanks again for the help and any more!

 

[CDW6212R]

Having the PCM code would help most likely. You have done many tune-up items, that's my first thoughts about it. I have read somewhere here about a problem which ended up related to something around the tank, an emisions hose loose I believe. Look around the back of the tank and the spare tire, there is an emissions hose which leads from the tank to a vent container, plus to a charcoal canister above the tire. Feel around to be sure those hoses are all in place. That is just another guess, with a code to steer you, it would be simpler to hunt I believe. Good luck,

 

[Rock99and9]

Having the PCM code would help most likely. You have done many tune-up items, that's my first thoughts about it. I have read somewhere here about a problem which ended up related to something around the tank, an emisions hose loose I believe. Look around the back of the tank and the spare tire, there is an emissions hose which leads from the tank to a vent container, plus to a charcoal canister above the tire. Feel around to be sure those hoses are all in place. That is just another guess, with a code to steer you, it would be simpler to hunt I believe. Good luck,

Thanks for the advice. But have an update. We drove the truck last night to the friends house. It sounded different to me during the drive, my wife didn't really notice. The truck was idling lower and lower at each stop. Just before arriving the engine did finally shut off. It did this once again as we stopped at the house. We opened the hood and started the engine and heard the hissing..... Vacuum leak...

After my other searches for leaks I realized I hadn't really moved hoses, or wires around much while looking. On the passenger side above valve cover and under one other line and the radiator hose my thumb closed the leak and the engine resumed it's normal idle. Have no idea yet what vacuum line this is, but once it is replaced hope it solves the problem. We "band-aided" the hole and drove home. Was now pushing 11PM.

Will post to the forum if this solved our problem.

Thanks again to all who replied, offered advice, or even read and thought about our problem. Great forum, may not be around alot but will try to help out if and when I can.

Keep up the great work!!

 

[CDW6212R]

It sounds like the vacuum running to the AC heater control valve. Those are the most common along the sides and front of the engine.