Electrical Gremlin in my Engine!

[brokn]

I have a 2002 Explorer XLT 4.0L 6-cyl that was running great when it was parked one day, but the next day when started it was suddenly doing the following:

• Started running with a miss when started up.
• When sitting still at a light with the engine running, the engine light would start flashing, then when driving the light would come on solid.
• When accelerating, it would spark knock horribly at certain rpm's or ranges, most notably around 2000-3000 rpm.
• Changed/replaced plugs & wires, but not much wrong there. Runs slightly better, but not really much.
• A few days later, under a little more than light acceleration, the engine started making a much more consistent and louder knocking sound, and does all the time now. This doesn't seem like a mechanical knocking, due to inconsistency - this is a spark knock, versus something like a bearing.
• Coil pack not giving any inconsistent or erroneous readings.

Checked codes, which were the following:
PO172, PO300, PO301, PO302, PO303, PO316

Doesn't seem like it's the O2 sensors. The mileage is worse than normal, but not so much so that it seems like the O2 sensors, but I'm not a mechanic.

What strikes me is the fact that it went from great to crappy overnight, and suddenly.

Does anybody have any thoughts on what the problem might be? Like everyone these days, I can't afford to just experimentally replace a bunch of stuff.

Any help welcome - thanks!

 

[hkg53]

Did it also seem to loose power as well?

I had an 02 Explorer that I just traded in, at any rate, I had a similar problem with the spark nock and such then one day I couldn't go past 30 mph. It was my fuel filter. Which was located under the passenger side of vehicle behind a guard.

If memory serves, it was around 80 K miles.

Just a thought.

 

[brokn]

Hasn't lost power; still as powerful as it always was. But thanks for your reply!

 

[swetrid]

The noise could be timing chain guide issue. When misfires are present on each cylinder in the same bank(bank 1), it is possible that the engine has jumped time. That would also give you the rich code you have.

 

[brokn]

Thanks for the reply, swetrid. I'm not a Ford tech (actually I'm a marketing analyst), but if it jumped timing, wouldn't it run rough all the time?

In my case, it runs kind of rough when idling, but at higher speeds (like on the highway) you can hardly tell there's anything wrong.

I was toying with the idea of maybe the VCT solenoid. Do you think that could be it?

 

[waskly]

02 does not have vct.

 

[1998Explodasport]

I have a very similar problem on my 4.0 SOHC Sport, I get almost the same codes except I get the P0174 instead of P0172. Engine sounds like crap and runs really rough at idle but if I am on the highway it has plenty of power and the only time you notice an issue is at idle. I changed plugs, wires, coil and checked compression on the passenger side and it was fine, around 140psi. I didn't check bank 2 because bank 1 was always the first side to throw missfire codes.

 

[brokn]

Hey, yeah, that's exactly the same thing happening with mine! Did you ever find out what was wrong? Thanks...

 

[waskly]

I have a very similar problem on my 4.0 SOHC Sport, I get almost the same codes except I get the P0174 instead of P0172. Engine sounds like crap and runs really rough at idle but if I am on the highway it has plenty of power and the only time you notice an issue is at idle. I changed plugs, wires, coil and checked compression on the passenger side and it was fine, around 140psi. I didn't check bank 2 because bank 1 was always the first side to throw missfire codes.

compression test bank 2, these engines have problems on bank 2 not 1...

 

[1998Explodasport]

Hey, yeah, that's exactly the same thing happening with mine! Did you ever find out what was wrong? Thanks...

No, I never figured out the problem I gave up trying to find the problem last month. As someone just mentioned I might as well check compression on Bank 2.

I probably will end up driving it until it dies and then replace the motor with a lower mileage one. After I pull the motor I will definately tear it down to see what the problem was.

If you ever do figure out the problem post it up here, I doubt we are the only two with this problem. The only code I am not getting is P0316 and I don't even know what that is. Also when I monitor the fuel trims Bank 1 is running rich but for some reason it won't set the code.

 

[brokn]

What if the cam-chain tensioner has gone bad & is no longer keeping the cam-chain tight? Could it cause this loud knocking in the front of the engine, yet not be slack enough to jump time? (Yet.)

 

[1998Explodasport]

Any update??? I'm gonna start playing around with mine again tomorrow or friday. I remeber last year a 2000 Explorer SOHC with 69k came to my shop with the same symptoms. It came from a dealer and he didn't want to spend alot of money so he wanted to try plugs and wires and a used coil I had laying around. I wasn't supposed to diagnose anything just replace parts. So I replaced all this stuff with no change and he was disgusted. I scanned the truck and it had one code P0174 and that came soon after I hooked the battery back up I was never able to scan it again to see what the other codes were.

He told me he was done putting money into it and was going to run it through the auction. I suggested intake gaskets and he didn't want to do it. So I just saw him a few days ago and asked him what happened to the Explorer, he claims a Ford tech looked at it and said it needed a motor which they all say when they don't know what the real problem is.