Rough starting and idling

[zfarmer]

Hello, I am going to try to explain this as well as I can. I have owned a 1999 explorer sport 4L SOHC for about a year now and have never had any major problems.

I noticed right away that the temp Guage and oil Guage do not work correctly on the dash. It takes a few minutes for the oil needle to tick up and the temp Guage starts out way below the Cold line and barely makes it past the line when running. When idling for awhile, the temp needle goes almost halfway up.

So for the problems, when the motor is cold, it starts up right away and idles perfectly fine. If I turn it off after driving around, it can start right back up. But if I turn it off and come back like 15 minutes-few hours later, it is fairly tough to start and I have to throttle it quite a bit and it starts up with a rough idle. Then the next morning it's back to starting up fine.

I bought it last July and I had these problems until Winter came and it didn't have any problems at all thru winter. Now that summer is back and it's hot outside this problem is back.

If it helps, I have sprayed for a vacuum leak, changed the egr valve and recently put a new fan clutch in.

I'm not sure what I should try to change next, I reckon a temp sending unit is fairly cheap but is there something else I should try?

Any ideas or pointers would be greatly appreciate

 

[KeenKilo]

If there’s no codes then maybe your idle air control valve IAC is sticking. You can clean it with carb cleaner or something like that. There’s a lot of diagnostic to be done before throwing parts

 

[XLTrunner]

Sure sounds like it could be a defective ECT sensor...but, that usually sets a code. Be forewarned that if you attempt to replace the Temp sending sensor, the blind nut will most likely just spin inside the t-stat housing and not allow removal. Haven't had that problem with the ECT sensor for some reason, though.

 

[RickOTR]

Sounds like your fuel injectors are leaking down. Mine did this until I replaced them. Problem solved...