Greetings,
I recently bought a 2003 Navigator with about 200,000 km. When I looked at the truck it was not running very good and it had a check engine light, however the price was right so I took a chance. When I got it home, I immediately checked the EGR hose and found that it had quite a large split in it. Several days later I replaced the elbow and started the truck. It now idled much better, and the check engine light went out, however it still feels like it has a miss. I only idled in the driveway for about 20 min, and did not drive it because I do not have it licensed yet. At idle, the engine sounded smooth but I could feel a shake in the truck. With the truck in drive and my foot on the brakes and revved up to 1500 rpm, the engine felt like a miss.
My question is, does it need to run longer and drive some on the road, for the computer to reset things after running for an undisclosed time with a badly leaking EGR hose. Or is the miss I feel a true miss.
I am guessing that if the engine has a miss, that it is an ignition coil. Is there anyway of telling if it is a coil when there is no check engine light. I do not know of any auto parts supplies that have scan tool for borrow.
Also, how huge of a job is it to change the coils? I changed that coils in my '98 Exped, and that was not a fun job. I can't even find the coils on this truck.
Thank you for your help,
Kevin

 

Running longer will not make a difference, there is likely a misfire. Without the CEL being set, your other option is to get your hands on a scanner that views live data. The live data will show misfire counts per cylinder. Changing the coils is better than past models. Look for a plate on top of the valve cover and remove it to see the coils.

 

Down here, Autozone, OReilys, and Napa loan OBDll testers. I'd check a local dealer and see if they too, loan them. They know you'll spend your money there.

Also, sometimes, a Code can be found even when the CEL doesn't come on. I would expect a P0300 series code prompted. The last two digits would be the cylinder location. 1-4 passenger side. 5-8 on drivers side, front to back.

Good luck.

 

I have a cheap tester. The truck does not have a check engine light, and the tester is not showing any codes. I had changed all 8 ignition coils, spark plugs, and fuel injectors on my '98 when I first got it, and it ran great for me for several years. I am leaning heavily towards doing this on this truck as well. Also, I am assuming that if one coil (guessing this is the source of the miss) needs to be replaced, it won't be long until another fails. The truck will primarily be used to tow a 6500 lb boat long distances and into some remote areas. I would rather not have a problem on one of these trips.
Thank you for your help.

 

That is a false assumption, but, if it makes you feel better replacing all of them, then do whatever you want with your money and your truck.

 

Agree. More chance it's the boot then the actual COP anyways.

A 2003 Navi without a CEL? Not sure what you mean?

 

By no check engine light, I actually should have said that the check engine light did not illuminate.
When you say that the miss is actually more likely caused by the boot, than the COP, are you referring to the boot (2 or 3 inches long) on the end of the ignition coil? Because if you are, in my mind that gives all the more reason to change all 8. If one boot is bad, probably caused by age, dirty, heat, etc, then all 8 would probably be showing some age (assuming they have never been changed). Therefore it is likely to happen again within the next 3 or 4 years that I own the truck. Especially because it will often be used for some hard driving. To me the price of coils is less that the trouble of a breakdown far from home.

 

Yes, the coil pak boots. You can buy them separately if you want to save a few bucks. If not, just like the dealer, they'd love to change them all.
Borrow an OBD ll reader and see if any codes have prompted. It can happen even thought the CEL isn't illuminated. You will get that P0300 series code to determine exactly where the misfire is.

 

True but...FYI, OEM coil=$75 ea....OEM boot=$3 ea.

8 coils=$600
8 boots=$24

 

I consider boots and springs to be service items to be replaced when spark plugs are replaced. Quite a lot like plug wires on older engines.

That said, plan on a complete COP and a spark plug once the faulty cylinder is identified.

If you do not yet have a misfire fault code, you'll need to dig into the Mode $06 PID $53 data to see which cylinder(s) is giving the trouble.

 

Not sure where you guys are buying 8 COPs and getting charged $600... they're $350 on Rockauto for 2V and 4V ones.

And +1 for the boots/springs. $30 kit on Amazon, just did this myself. The electronic portion of the COP rarely goes bad, its usually the boot is rotted or the spring is rusty or both. My COPs had boots in ok shape but half the springs had rust spots all over them and I was getting misfires.

 

Dealers and local auto parts stores charge around $75 each.

 

I should have stated "why in the world would you pay that when you can get them for half?". I mean I know when someone is under the gun and HAVE to get the car back on the road ASAP but its just really excessive especially since they can be rebuilt for real cheap and one can even get a set of 8 used (tested good) OEM ones for like $50 and then just rebuild those and you are good.