Hi everyone,

I have a 2001 5.4L 4x4 that has been idling too high sometimes while driving and sometimes while in park. The first time I had the experience I had acid buildup on the battery terminals. I cleaned this off and everything worked fine for maybe a year. Then a few of months ago it happened again. I replaced the idle air control valve thinking this may have been bad. Then after I installed the part I bumped the battery connector and it popped off. I remembered the first time when the connector had acid build up. So I cleaned & tighted the connector but I broke it apart tightening it. I replaced it and the problem was gone. Then a couple of weeks ago the same thing started again. I immediately went to the battery and it was loose. I think the cold weather lately along with some grease on the connection kept making it work loose. I cleaned off the grease, roughed up the terminal and tighted the everliving dog crap out of the connector. But now the problem is still there. It will rev up about 1000 rpm above normal. It doesn't do it constantly but comes and goes. If your driving when it revs up you loose engine power even though it is still revd up. All this time I was convinced that it had something to do with the weak battery connection screwing with the computer. Now I am thinking that something else is going on. I also just started it and of course it revd way up and when I got out of the truck i could smell a faint scent of gas. So now I don't know what is going on. Can anybody please provide some advice? Thanks in advance!

 

A dirty throttle body/plate can keep it from closing all the way tight. Even open a fraction will cause the TPS sensor to register something above normal idle, and cause the fuel charge to increase to match the extra air flow. I'd check/clean that first.

As for the battery terminals, if you are pretty handy, I cut the original strap ends right off. From Auto Zone or wherever, I get a set of epoxy coated marine terminal ends, and a couple of #4 welding cable lugs. The terminal ends are a whole lot less money than those factory cables. The #4 lugs are just soldered on to the original battery cables where you cut them. Simple nut and lock washer attaches them to the marine terminals.

Dave

 

I pulled the air intake off and looked at the throttle plate. The front side is clean but the back side and inside of the throttle body are completely filthy. I cleaned this a few months ago and even then it wasnt that dirty I just cleaned it then to see if it would help before I changed the IAC valve. What would casue this? Could it be just a side effect of whatever is causing the high idle?

 

I checked the TPS voltage by using the directions in a Haynes manual. By checking the voltage in the sensor wires with it hooked up and the key turned on I should see an increase in voltage from 0.5 volts to somewhere between 4 and 5 volts (I can't recall the exact numbers) when the throttle goes from closed to open. I did this and there was no change whatsoever in voltage. I bought a new TPS from Advanced Auto for about $30 and installed it. I drove the truck around for about 15 minutes and have not had a problem yet. We'll see how tomorrow morning goes. Thanks.

 

Sometimes you have to drive several times after a problem develops, before a code is tripped, and the cel comes on. If you had the computer scanned, it might show pending code(s). It's possible that you repaired the problem before hand. You'll know in a couple of days. If it's still idling good tomorrow, try checking engine vacuum after warm idle is reached. If the engine is in pretty good shape, you should have 18-19", and pretty steady.

Dave