My mom wants to sell her 2002 Ford Explorer w/ 4.0 as enough kids have moved out that the vehicle is no longer needed. It has 162 000 mostly trouble free miles on it. However, for me to sell it for her, I need to get it running well first. The background:

Just recently it fried the alternator. No big deal, got a reman for my dad and he put it in. But now it has this sort of "shudder" at idle and low rpm, and also when accelerating slowly low in the revs. I don't know if it was there before or not because only my siblings drove it, and their not exactly observant. I am positive it is a misfire.

So far I have done the obvious. I have pulled all the plugs, they are nice and tan, re-gapped them (although they were only .002 out of spec at the most). I noticed that one plug wire was broken on the inside, where it connects to the plug. Thinking I solved the problem, I bought a new set of wires and put them on. No such luck however, as the problem continues unchanged. On the new wires, I have verified tons of spark making it through. In an effort to isolate the bad cylinder, thinking maybe it was actually a plug, I started pulling wires off the coil with it running. I could barely notice a change in the engine with any of them, and a couple seemed to have no change at all (again, I may just not have been able to detect it because I could barely make out the other changes).

Next, thinking maybe it was fuel related, I put a stethoscope on some of the injectors and they sounded the same, but I can not get at the back passenger and 2 back driver ones. How else can I test these?

I even went so far as to unplug IAC, engine died immediately so its not that. I also took off the EGR valve and cleaned it, and pushed the plunger up and down lots and it moves freely. I tried pulling off the vaccuum line from the EGR with the engine running and there was no change, but that doesn't really mean anything does it?

So I put it all back together and thats how it sits for the night. On a related note, the CEL is on, but it is on more often than not on that thing, and my dad has taken it to a dealer three times to have codes read and nothing ever shows up. The mechanics keep saying that it has something to do with the fuel cap and pressure or something.

Without making it run right her $5000 vehicle turns into a $2000 or less one, so I need to get this cleared up. What have I missed???

 

first i would not regap old plugs, time for new ones. Around here you can go to Auo Zone and they will read the codes for you. Post here and figure out which cylinder it is. You could also have a coil problem and need new, but need to figure out which cylinder.

 

Regarding the EGR, you're correct, pulling the vacuum hose off when the engine is at idle does not really tell you anything. At idle, the EGR valve should be closed. The test would be to pull a vacuum on the EGR valve and as the valve opens, the engine should begin to stumble or stall.

As mentioned above, try to get the codes read and post back the exact code numbers displayed. It's quite possible for what the dealer charges for one time having codes read you could have purchased an inexpensive code reader. For two reads, you could have put that money towards a more useful entry level scan tool.

If your mom is the type of driver who rarely gets aggressive with the accelerator, you might want to use some SeaFoam and perform a cylinder de-carb (instructions are detailed on the can) and see if that helps out. Maybe there's enough carbon on the valves that it's acting as a sponge for the fuel or restricting flow in and out of one or more cylinders. Also, consider cleaning the Mass Air Flow sensor, especially if this vehicle has or has had an aftermarket "performance" air filter installed.

-Rod

 

Cleaned the MAF already.

Not gonna buy new plugs unless that is the problem, becuase like I said this vehicle is getting sold immediately upon running right so I want to spend as little as possible.

I think what I need to do is see if I can get a loan a tool scanner and vacuum guage. Apply vacuum to EGR to verify its working, which I am fairly sure that it is. Get codes read. Gonna buy some more carb cleaner cause Im out of that anyway, spray around and see if there's any vacuum leaks. If those don't turn up anything then Im back to checking the fuel system, possibly a bad injector or plugged filter?

As for the coil, when I was pulling plug wires one at a time, each of the cylinders was arcing from the coil to the plug wire up to an inch away, so I am tempted to think that's ok. Codes will tell I guess

 

$50 for a vacuum pump? How about $1.25 for a vet syringe from the farm store . Tested EGR, applied vacuum and engine almost stalled out at idle so that's good to go.

Luckily enough one of the automotive stores had an OBD II scanner on sale, so I picked that up. Here is where it gets interesting though... when plugged into the port under the dash, nothing happens. It is not even recognizing that it is plugged in. I used on my 01 F-150 and the scanner works fine, exactly as it should, reads no problems. So why is it not connecting to the exploder? Does this mean that there is a computer problem?

I am out of ideas as to what to try now. I suppose I could buy a pressure guage and check fuel rail pressure and all that, determine if the filter is plugged or not, but I wanna hear what people say about the computer first before I spend the money.

 

AHA! Blown OBD and lighter fuse. Changed fuse, got a ton of codes! The codes:
P0113
P0304
P0316
P0401

These codes were "pending", I dunno what that means:
P0305
P0306
P1121

Looks like she's got a few misfires... currently number 4 cylinder apparently. No injector codes or anything of the sort though, so looks like its not fuel related? I guess at this point I'll just buck up and change all the plugs with some new autolite platinums.

 

Fixed! I got all new plugs, the ones in there were Bosch platinums or something. I replaced them all with Autolite single platinums, and its now running smooth as can be!

Now up for sale she goes

 

new plugs will do wonders, and fix about 70% of the EXP problems with missfire.

 

I'm glad to hear you got it fixed. Another tick against Bosch plugs in a later model application.

For future reference, a misfire does not need to be only ignition related. A fuel injector that is not working properly can also cause a misfire. The code is triggered when a particular cylinder is not firing as expected. Not firing can be due to lack of spark, lack of compression, or lack of the proper air/fuel ratio.

-Rod

 

You would of been done alot sooner as well as cheaper if you changed the plugs from the start. Even if you said you wanted to be sure, at least you should of taken them out and checked them. Being that one plug was different it either a used car bought or a shops quick fix to charge the most with buying the least to maximise profit. Next time check the obvious 9 out 10 you will find your problem.

 

I havent had this car for long and just the other day , the check engine light came on. So when I got the codes read at Advance Auto Parts, I got a P0305 and a P1000 code. I have read up some online and have seen that the P1000 code is minor and that the P0305 is a cylinder 5 misfire. The misfire isn't noticeable at all and the car appears to run fine all the time ( I may just not notice it) . Anyone have an idea on what I should look into as far as fixing the issue with the codes ?

 

The P1000 probably means that just before you bought the Explorer someone cleared the diagnostic codes and you have not driven it long enough without an issue for the drive cycle to complete.

The first thing I'd check for the P0305 is pretty much the subject of this thread you posted to - spark plugs. At least remove them and inspect them to see if they all look the same. Pay attention to which spark plug comes from which cylinder. If the one from cylinder 5 looks different, how does it look different? Is it dark and oily in appearance? Is it dry and whiter than the others? You probably get the idea.

If the spark plugs appear like they've been in the truck for quite some time you might want to change them out with new plugs. I would suggest NOT going with some exotic plug. Stick with something very similar to what the vehicle came with (probably a single platinum tipped plug). You should also pay careful attention to the spark plug wires. If they still say "Motorcraft" on them, they are probably original and due to be replaced. Spark plugs and spark plug wires are routine maintenance items so changing them with a quality replacement (don't go cheap on the spark plug wires) is not money wasted.

-Rod

 

To detect a vacuum leak light a cig and move it around the engine to see if it starts sucking the smoke in if it does that's where your leak is I just had to do it on my 2000 Ranger. But like buddy said it's most likely your coil pack