i belive its 2 sep. problems? please help!

[ahxlt98]

I have a 98 ford explorer xlt 4.0 sohc all wheel drive 4x4. When i got the suv it had sat for almost a year. I have replaced the alternater, battery, spark plugs.A few months ago it started to idle funny anytime i started it while cold it would idle up then down then up then down and eventually die until the engine was warm. After it warmed up it would be fine. Eventually it got to where it would do it when it was warm or cold and seemed to get worse if i would start it up and turn the fan on high with the heater. Idle would fluctuate and eventually die.I have to hold the brake and gas while driving because it will die at stop lights or even if i am slowing down to turn or make a stop. Some one told me to check the mass air flow sensor so i unplugged it and it would stay at idle until it got warm and then it would do the same as before it warmed up so i replaced the maf sensor and i am still getting the same result. Also to go along with that I have the loud tapping or rattle coming from under the hood. i have been reading some posts about it being timing but i am not sure. the rattle started with only while the truck warmed up as well but two days ago it started doing it all the time warm , cold, while driving. it goes up and down with the idle or throttle, i hear it coming from on top of the engine driver side mostely but when i climb under the suv i hear it there around cat converter. i tried the screw driver to the engine trick to listen internally and i dont hear anything from there, also tried taking the serp belt off and still heard it there. I really need to fix this since its my only family vehicle but i dont have the right tools to figure it out, nore much experiance with ford products. I did put a scanner on it before replacing the maf sensor and it was saying the maf had a low reading and i had misfire that is when i replaced both the maf and the plugs, also reset the cpu, dont have acess to scanner since it was borrowed. any comments or suggestions i am mechanically in clined and can borrow tools if its not a huge job to fix what it might be.

 

[ahxlt98]

also the rattle almost resembles the sound of a heat sheild but i have removed them and replaced bad muffler

 

[swshawaii]

I did put a scanner on it before replacing the maf sensor and it was saying the maf had a low reading and i had misfire that is when i replaced both the maf and the plugs

Check firing order on all spark plug wires, especially #5 and #6 , very commonly switched. Coil on right side of diagram.

 

[2000StreetRod]

timing chain rattle?

There is a good possibility that your engine is exhibiting timing chain rattle: Timing chain rattle resolution process - SOHC V6
Around here a 1998 with timing chain rattle can be purchased for $800 to $1500 depending on the exterior and interior condition. If the rear cassette is broken it will cost more than $1500 to have the engine removed, the cassette replaced and the engine reinstalled. If you are mechanically inclined you can do the repair yourself for under $500 but it is not a simple process and a special tool kit (OTC 6488 for $150) reduces the risk of doing it incorrectly. Many members in your situation just drive the vehicle as is until the engine destructs.

 

[ahxlt98]

i was hoping for your reply 2000street rod, i read a few of the posts you have put up on this subject. tonight i had replaced plugs and wires and i gave it an oil change. while doing that i used a stethascope to try to pin point the noise....i hear it the loudest coming from the left front right around the power steering pump. i was kinda hoping timing in front not back if at all. is it possible for the power steering pump to make this noise? i put the steth righ ton the pump and it was almost defining every where else was ya i hear it but its def from around the pump.

 

[2000StreetRod]

not the power steering pump

In your original post you stated that you removed the serpentine belt and the rattle was still present. Therefore, you eliminated the power steering pump, water pump, alternator, A/C compressor, belt tensioner and idler as the source. I used a mechanic's stethoscope and a length of flexible hose to try and isolate my rattle. I decided it was the left cassette but when I removed the valve covers I found it was the right cassett. When I removed the front timing cover I found the primary (crankshaft to jackshaft) chain tensioner was also failed. Internal rattles echo within the block making source location difficult. The only reliable method I'm aware of is direct inspection. Unfortunately, in the case of the rear cassette that involves removing the valve cover.

You didn't post the odometer reading but with the age of your vehicle I predict the primary tensioner has failed if the original one is still in place. A failed primary chain tensioner rarely resutls in engine damage.

Since your vehicle has 4WD, there is a good chance that the balance shaft tensioner has failed. A failed balance shaft tensioner rarely results in engine damage.

Since your Explorer is your only family vehicle you will need to minimize down time. I suggest purchasing the upper and lower intake manifold gaskets and the EGR tube to upper intake manifold O ring. Then inspect for cassette damage when installing the gaskets to decide a course of action.

 

[1Aauto]

Welcome to the site.

 

[ahxlt98]

Ok. First I am taking everything posted as good information. But before I dump more money into this suv I decided to check the codes again after the tune up......its saying camshaft positioning sensor is bad. Now I know it may not explaine the rattle but it may fix the fluctuating in the rpms and sluggish power in turn buying me a little time on the timing. Its a cheaper quicker fix and ultimately i will more than likely rebuild the engine after getting my other truck back on the road. Thanks for all the advice and I will keep posting on this as I fix.