Coil Pack Question

[virgamanda]

My 1997 4.0 Explorer shut off for no reason today while idling in a parking lot. I started it back up it ran for a second then off again, i tried 2 more times same thing. Then it finally started, ran a little rough and drove fine for the rest of today. My first suspect was the coil, maybe I am wrong. The ohm readings are as followed: Primary Resistance is .6 on all leads, and secondary resistance is 13.2 k at all test points. The haynes manual says the primary readings should be .3-1.0 ohms and the secondary readings should be 6.5-11.5 k ohms. So according to this, my secondary readings are to high. Would this cause my problem? I have 180000 miles on this truck and the coils looks to be the original. Anyone have any ideas. BTW plugs and wires are pretty new, new fuel filter a couple of months ago, fuel inj cleaner run every oil change, get same gas at every fill up. Any help is appreciated.

[shorod]

Your symptoms sound more to me like a weak fuel pump, but there are a few other items you should check out to narrow the problem down, unless you want to shotgun parts.

If this condition is something you can duplicate again, I'd suggest you keep a fuel pressure tester handy and check the fuel pressure the next time it won't start. Since you've recently changed the fuel filter, that probably isn't the issue.

Also, are you running a K&N or similar air filter? If so, your MAF sensor may be contaminated and need to be cleaned. Have you checked for codes, specifically misfire codes? When the engine started but ran rough, did the exhaust look or smell odd, like raw fuel?

-Rod

[virgamanda]

Originally Posted by shorod

Your symptoms sound more to me like a weak fuel pump, but there are a few other items you should check out to narrow the problem down, unless you want to shotgun parts.

If this condition is something you can duplicate again, I'd suggest you keep a fuel pressure tester handy and check the fuel pressure the next time it won't start. Since you've recently changed the fuel filter, that probably isn't the issue.

Also, are you running a K&N or similar air filter? If so, your MAF sensor may be contaminated and need to be cleaned. Have you checked for codes, specifically misfire codes? When the engine started but ran rough, did the exhaust look or smell odd, like raw fuel?

-Rod

Yes I do have a K & N air filter and recently cleaned and reoiled it. I did not consider that. There are no trouble codes showing. The exhaust did smell kinda rich.

[shorod]

Ahhh, cleaned and probably over-oiled. It's easy to do!

I'd suggest then that you start by carefully cleaning the MAF sensor elements. CRC makes a MAF sensor cleander spray that can be purchased at some of the chain auto parts stores. See what happens after cleaning that.

-Rod