Rough idle.

[jordan101]

i have a 97 explorer xlt with the 4.0 sohc. When i bought it 5 months ago in the summer time nothing wrong. well when it got colder i start it up it will idle at 1200 and then when it warms up it will idle at 600 and every so often go back and forth between 600 down to 300. i have a scan tool and the code is p0153 which is an o2 sensor. and every now and then the lean code pop up but it is pending. Any sugguestions? I think it is the o2 sensor causing the car run lean.

 

[BrooklynBay]

Welcome to this forum! Check for vacuum leaks.

 

[jordan101]

any specific vac leaks that causes this.

 

[BrooklynBay]

Check the vacuum lines, and the intake manifold gaskets.

 

[jordan101]

ok thanks never replaced manifold gaskets on these specific vehicles but its probably easy i would think.

 

[jordan101]

my spark plugs and wires look like its been awhile since changed. Will this cause any of it?

 

[jordan101]

remove intake mani

How hard is it to remove the intake manifold on the sohc 4.0 engine? never done it on this specific vehicle.

 

[BrooklynBay]

Everything is bolted on, so it shouldn't be that hard to do.

 

[drothgeb]

http://www.explorerforum.com/forums/showthread.php?t=261439

The first part of this link shows the removal process. Just take it slow the first time and make sure you get all of the torx screws because the manifold is plastic and can break. Also, do NOT drop any screws/bolts/anything into the cylinders once it is off (cover them with clean shop rags). This isn't too hard and should only take a couple hours tops the first time. Good Luck!

 

[BrooklynBay]

I would start with the spark plugs & cables if there are no vacuum leaks. Both of your threads were merged, and moved into the stock 95-01 section.

 

[jordan101]

Ok i took my vehicle to a mechanic who has a better computer system than i do. Well he told me i should go ahead and get a tune up bc the plugs and wires were so old. The guy i bought from said they were new but werent. Anyways i got plugs/wires and fuel filter changed. My fuel pressure was where it should be. He checked my vac lines and intake mani gaskets. He said neither had a leak. But after he was done car did run 1000 times better when hot. next morning i woke up it was like 20 deg. outside and i started up and it ran the same. i was like wtf. I took it back he told me he had parked the vehicle in the shop overnight. the car did pull p0174 lean on bank 2 which was the fault and the same side upstream sensor was pending. He also told me it does has an exhaust leak. do you think the exhaust leak is making it run rough in the morning or the intake gaskets?

 

[rego]

I've never heard of an exhaust leak causing a lean condition. I wonder how he checked the vac lines and intake gaskets. Some guys have used some sort of smoke test with good results. Also if it is an intake gasket, someone reported tightening them as a fix. I don't know if he made a follow-up report that it is holding or not. Good luck.

 

[jordan101]

Ok thanks rego. i know he checked the inatke gaskets in a warm shop so i told him to wait till this morning out in the cold to check bc thats only when it seems to run rough is when i first start it. Like i said the fuel pressure was where it should be so it getting more air somwhere. i think from the gaskets but ill wait and see.

 

[2000StreetRod]

Probably leaking intake gaskets

If your 97 has never had the upper and lower intake gaskets replaced then I suggest doing it even if it is not the source of your specific problem. The old style thin gaskets shrink with age and leak when cold. The new style gaskets are much better and inexpensive to purchase. If you do it yourself a 1/4 inch socket set with wobble joint extensions will simplify the process.

 

[jordan101]

ya thats what i was thinking but i dont have a shop and it snows alot this time of the year where i live so i have to take to a mechanic.

 

[rego]

I have snow and cold too. That is why I'm putting my po171 condition off 'til spring or summer. I have the 4.0 ohv and have erased the code and it was slow to return. Mine isn't running rough so maybe it's not as bad as yours.

 

[jordan101]

Well good news i found the problem. The mechanic kept saying the intake gaskets werent leaking so i tried the smoke idea. Sure enough it was leaking pretty bad on the upper. I found another mechanic who will replace for 250 thats parts and everything.

 

[Joe Dirt]

Glad you got it figured out, Jordan... Always nice to get a second opinion on stuff like that.

 

[jordan101]

Well pulled the manifold off the gaskets didnt cause it the whole mani was warped.Oreily auto has it for 49.99 in my area and it includes all gaskets.