help diagnose ford explorer 4.0 sohc??

[screamin gt]

EDIT: if you dont want to read all that crap.... both banks lean. erradic idle when cold (to almost stalling out) but fine when just a little warm. changed TPS, ECT sensor, IAC valve, fuel filter, MAF (twice), both o2 sensors. no change.

I recently bought a 2000 ford explorer and its driving me nuts. I bought it used but from a dealer, sort of thinking it would be more likely to be problem free since I usually buy from private party sellers and have to figure out why they sold it and fix it. unfortunately that backfired.

anyway day after I drove it away, the CEL comes on. bring it to autozone for the reader and the codes are : right and left banks lean, emmissions system error, and random misfire.

brought it back to the dealer I bought it from and he says its most likely an intake seal leak, so he changed that and ripped me off for an hour labor. (In CT they dont have to warranty any vehicle over 7 years old) so he says its all set and running great and come pick it up.

CEL comes on, on my way home from there, and I kinda figure this guy is just gonna keep ripping me off so I decided I'd try to fix it myself from there.

symptoms BTW are: running like crap from a completely cold start. drops from 1500 or so rpm's to 500 and about to stall, then way back up and repeats over and over till warm, then its fine. (the guy had it all warmed up when I went to look at it so I wouldn't notice the erradic idle.)

so I get the same codes and start with the mass air sensor, tried cleaning it first but that didn't work and the sensor wires looked a little pitted and whatnot so I thought it was a good guess and got a new one. no difference.

next I tried the tps since it was cheap and easy and sort of made sense. no difference but one of these did take care of the random misfire and emmissions codes, all thats left is the lean codes.

next went with the ECT sensor since the problem is only when its cold. no dif. then tried IACV. no dif.

Btw also sprayed all around looking for vacuum leaks and couldn't find any. actually did that first.

also tried replacing the fuel filter since its cheap and easy. nothing there.

gave up and brought it to a local garage, who's first thought was whatever the emmissions problem was had messed up both o2 sensors, which made sense. he tested them and said the readings were all out of whack and so we changed those. nothing. he was convinced the mass air sensor was still bad even though brand new, and thought it ran better with it unplugged (different yes but not better) so since I had the year warranty on that I swapped it for a new one for nothing. no diff. (and yes cleared all codes after changing that)

lots of people also say maybe the gas cap. I doubt that would cause idleing issues but ok since the mustang is the same I just swapped them. no difference.

out of ideas and running out of patience. anyone got anything for me?

 

[SVT32VDOHC]

Jumped time? Those SOHC motors are notorious for bad rear timing chains. Was it ever making any noise?

 

[Smokeurhonda]

Dude, I know you checked for false air leaks but very rarely have I been able to find one by spraying gumout around the manifold. It really sounds like a vacuum leak. If you have some form of a scanner I would check your fuel trims to see how off they are. When it's cold you can also try entering some propane to the induction, see if the idle levels out.

Also like SVT said above, timing could have jumped, if it did though it would make sense to me that you would probably notice the problem all the time, and it would kick some kind of cam/crack sensor code.

ALso just look at all drivablility sensors with the scanner and make sure all are within "normal" parameters.

 

[Notchbck93]

With reading being way out of whack, have you checked to ensure the ground wire was hooked up for both 02 sensors, especially after an intake manifold gasket installation.

Do you still have your stock oil fill cap on the truck? The little K&N ones will cause lean readings if not properly rememedied.

Check all hoses as well.

A very common problem with the 4.0 litre SOHC engine

The intake gaskets are leaking these are rubber orings around the base of the lower and upper intake plenum

When your engine is cold the plastic contracts or shrinks causing a vaccum leak at the intake causing the lean readings and idle rough

When the engine warms it expands and closes those gaps in the plastic intake around the gaskets thus stopping the vaccum leak and then the computer can control the air/fuel mixture

Those gaskets are not that easilly replaced but can be done in a short time by an expierienced technician
This should correct the problem

Ford Senior Master Tech


Exhaust leaks can also cause problems pre 02 sensor. Your intake manifold could be warped.

 

[Notchbck93]

I also found this with a quick Google search

Well, since YOU are a mechanic, I guess I can explain it in technical terms. This was an Owner Nofication Program released by Ford to address "engine runs rough when cold, and makes rattling noise upon start-up" concerns. If your Explorer has the 4.0L SOHC engine (eighth digit 'E' in the VIN), this "program" applies. This engine is a derivative of the 4.0L OHV engine it replaces. In place of the camshaft, a "jackshaft" is used to drive the bank #2 "cassette" at the front of the engine, while bank #1 cassette is driven at the rear of the engine. Ford came out with this program with an updated bank #2 (driver side bank) timing chain (or cassette) tensioner, and a plastic restricter tube that is to be installed into the oil gallery adjacent to the tensioner. They also updated the intake o-ring gaskets to make it less susceptible to swelling up and leaking. To carry out this repair, go to your nearest Ford dealer parts department, and ask for part number YL2Z-9E473-AA.

To carry out this repair, remove the four 7mm or 9/32" bolts that secure the 4.0L SOHC engine dress cover, and remove cover. Remove the two bolts that secure the speed control and throttle cables to the intake (again, 7mm or 9/32"). Remove the air inlet from the throttle body and the air cleaner housing. Remove the two 10mm bolts that secure the IAC to the intake, and remove the IAC valve. Disconnect the PCM bulkhead connector on the firewall by loosening the 10mm bolt. Disconnect the adjacent harness bracket and PCM ground by removing the 11mm or 7/16" Nut, and then the stud underneath. Set harness aside to make access to the back two upper intake fasteners easier. Remove the eight Torx self-tapping fasteners that secure the upper intake plenum. Remove the two white plastic clips that secure the plastic PCV tubes to the upper intake, on the lower side of the intake. Remove the two small Torx fasteners that secure the EGR solenoid bracket to the upper intake on the passenger rear side. There are THREE rubber hose connections to the upper intake, disconnect them. Very carefully wiggle the upper intake off the EGR pipe near the front of the engine and remove upper intake. Remove the twelve 8mm or 5/16" bolts that secure the plastic lower intake to the cylinder heads. Remove the lower intake, and install the new o-rings after cleaning. Disconnect both the ECT and temp sender connectors on top of the black plastic thermosat housing at the front of the engine. Using a deep 19mm or 3/4" socket LOOSEN (but do not remove) the sensor/sender assembly closest to the timing chain tensioner button at the left/front corner of the engine. Using a 1-1/16" wrench, loosen and remove the timing chain tensioner button. Using the appropriately sized Torx socket, remove the oil gallery plug, directly beside the tensioner button. Install the white plastic restricter into the hole and install new Torx gallery plug (included in the kit). Install the new updated tensioner (with the "hat"). The rest of the job is just the reverse of the removal. Hope this helps.

http://au.answers.yahoo.com/answers2/frontend.php/question?qid=20071206172626AAxX3J7

 

[Smokeurhonda]

Good info bro!

 

[BurningRubber]

If the sucky timing chains were loose enough to jump a tooth they would more than likely be making noise.

We had to take one in under recall because of that, it was fairly noisy. Its starting to act up again... The chain didnt skip but I garuntee you had it kept running any longer it would have.

They are smooth engines but between the engine and tranny they are kind of a PITA...

 

[mikeG S281E]

i'm a ford tech. if you have ce light with with codes p0171,p0174 (o2 bank 1,2 lean) its 9 times outta 10 intake gaskets. if you have access to a scan tool to monitor pids pull up 02s, long term trim and short term. spray the intake with carb srpay and watch the pids. bad intake gaskets when carb spray sprayed will flatline the o2 rich and trims will go real rich. 4.0s are known for bad intake gaskets and fairly simple to do. if you running really lean it can cause a lean miss.


as for the chain i just had a truck in with the same symotoms ur having. his chain is making some hurendous tickng tho very noticeable and alot of work to do. if remember the cassettes go bad.take the oil cap off while the engine is running ull hear it.

so if you have a serious tick---- chain. for the lean and rough condition id go with intake gaskets. if you have common knowlage for cars u can do it yourself parts are like50 bucks. gl

 

[mikeG S281E]

oh and that post about the chain few above if remeber that was a tsb it was about the chain rumbilng and ticking on start up. it sounds like u start the truck with no oil. t was only on start up and cold engine

 

[screamin gt]

This was an Owner Nofication Program released by Ford to address "engine runs rough when cold, and makes rattling noise upon start-up" concerns.

that is probly it. it makes a hell of a rattle when the idle drops so low it almost stalls out.

like I said the dealer I bought it from said he changed those o-rings gaskets when I brought it back to him. of course thats trusting someone thats already prooved to be an ass. so I guess I'll try that one more time before I get into the chains/tensioners.

thanks for all the help guys! :SNSign: I'll keep it updated but I don't know when I'll have time to get into this truck again

 

[BurningRubber]

oh and that post about the chain few above if remeber that was a tsb it was about the chain rumbilng and ticking on start up. it sounds like u start the truck with no oil. t was only on start up and cold engine

Yeah that is how ours started out.

It wasnt long where they started clanking around even when it was warmed up.

Now it is starting to clank just a little at idle again, after the TSB with under 110k on it... lol.