engine won't stay on and runs cold

[yamanjoe]

I recently got a 99 Explorer 4x4 with the 4.0L V6 engine and Eddie Bauer trim I didn't need to use it right away so it sat a bit. I started it up every few days and drove it around the parking lot. One time, a week passed and then when i started it up, it wouldn't stay started. I had to start it and keep it between 1K and 2K rpms. If i took my foot off the pedal, it would die. I had to do this for 10 to 15 minutes before it would keep running. I took it out for a drive to get it nice and warm but the engine wouldn't warm up, staying right around the C on the gauge. I don't know where to start. Is the thermostat stuck open? Is the fuel filter clogged? I don't hear any vacuum line hissing. Is it an engine compression issue? Does it need a tune-up? It has an aftermarket air filter with a chip. Is that thing malfunctioning?

 

[Turdle]

Is the radiator full? Reservoir might look good but how about the rad?

 

[974X4BLACKSPORT]

Look for a vacuum leak. Check all the little plastic and rubber vacuum hoses for breakage, dislodged, or chewed (by animals if parked out side). A stuck open thermostat is the first thing to check if the engine does not warm up fast enough, or at all, of course make sure it is full of coolant also. If you store the vehicle outside for any length of time, small animals have a way of finding their way to the air filter housing and making nests, starving the engine for air when it is running, I am not saying this is your problem, just something to check.

 

[yamanjoe]

I haven't seen any rodent damage but I'll go out and check more closely. Radiator is as full as can be.

 

[yamanjoe]

i didn't spot any evidence of rodent damage. I understand that the engine not warming up would be a result of a stuck open thermostat but could that also explain the inability to running on start-up?

 

[rasouth]

You did not mention how it drove when you took it for a test drive to warm up engine. Did it run okay? Accelerate okay? Any hesitation? Might check/clean the MAF sensor.

 

[yamanjoe]

It actually ran OK. There was perhaps a little bit of hesitation accelerating from a complete stop, or maybe that was only paranoia. It did seem to idle quieter than normal. I was scared it was going to stall at the stoplight and leave me stuck out there on the road but it got me back just fine.

I'll check about the MAF sensor.

Might it also be a dirty or faulty fuel injector?

 

[yamanjoe]

and you mention the MAF sensor. Might the problem also be that aftermarket air filter? How to check that? Would it be a good idea to find an OEM filter housing and install it and just get rid of that aftermarket one? If so, would the computer need to be re-calibrated?

 

[Turdle]

The check engine light is on yes? If not, check that it does turn on with key.

If it is running this poorly there should be a malfunction indicator light.

 

[EB4X]

I would remove that chip setup and see what happens....also....did you just oil the filter? ...if so that's probably your problem--it saturated your MAF-- in which case get some maf/ or electronics cleaner spray and delicately spray MAF sensor element. I'm guessing temp reading is coincidental and irrelevant to stalling issue...on that it's either your sensor went out or as discussed thermos stuck open.
Is this the OHV or SOHC engine? ....the OHV is known to have intake gaskets fail to some degree which would cause stalling....

 

[yamanjoe]

It is not pulling any codes. It's the SOHC engine. I just got it so I don't know what might have been done recently but yeah the MAF is something I am planning to look at. To be honest, there are so many things it could be that it is a bit overwhelming for me. I think I'll have a professional look at it and see what he says.

 

[rasouth]

A mechanic will give you all sorts of possibilities and might do all sorts of tests, most which you can do yourself, such as get rid of after market air filter, clean MAF, replace thermostat... Start with the simplest thing and go on from there. Most of these suggestions on this page can be done easily and cost effectively with minimal tools.

 

[Gerry1]

I will add my experience. I have a 97 XLT/ 4.0 SOHC bought new. The common issue with the poor idling when cold was the upper & lower air intake gaskets would get brittle. When engine is cold the gaskets would leak and you would need to baby the idle until the engine got warm ( gaskets got softer). I replaced mine as part of a kit (00M12 gasket kit) at 49k miles in 2009. I was putting up with the idle issue for some time before i found out about the gasket issue.
Another issue is very low idle, occasionally stalling. Most noticeable when backing up. That is the TPS- throttle position sensor. I replaced that a year ago at 116k.

Good luck,