2003 F150 Transmission issues.

N80 · Oct 8, 2015

Yes, neutral throttle, not neutral gear. Fuel filter is a thought. I hope it is not in the gas tank like many are these days. I will check.

dusty3030 · Oct 8, 2015

The Ford modular engines ECU was 50% hardware and 50% voodoo.
Coil pack problems suck because they often don't throw a code. A good shop familiar with these engines can hook a good scan tool and get the misfires per cylinder and either look further down that road or rule it out.

N80 · Oct 8, 2015

I have a fairly good scan tool that is showing nothing from the ECU. So far, the ECU on this truck has been sensitive and each time the problem has been cleared and resolved easily and predictably (PCV, thermostat stuck open, tiny vacuum leak etc).

I'll definitely keep the coil issue in mind but I still don't see why a coil issue would totally resolve with OD off and then recur fairly predictably with it on. But then again, as you say, there's the voodoo with most all modern engines..............

tman1020 · Oct 8, 2015

In overdrive it becomes noticeable because of the taller gear.

caver · Oct 8, 2015

I was told what is probably happening is the engine is lugging and your voltage is at its lowest.

N80 · Oct 8, 2015

Okay, so let's say it is a coil issue. Will the stealership have a tool that can detect this problem, in the shop, even when the ECU won't? With Japanese cars of this age this is not the case. If the problem doesn't happen when they run the diagnostic it will not detect it. In fact, on my old Maxima the dealership could not even tell me which coil was malfunctioning even when it did throw a code unless the problem happened when they ran the diagnostic. And again, it makes no sense to me that an ECU could possibly miss a series of three or four total misfires in a row and not throw a code. And if they are occuring, as you suggest, even in other gears and I only feel them when in OD, then that is even less likely.

But, I'm generally a pretty poor automotive diagnostician. So if the dealership can detect a latent coil issue with their equipment then I'll take it and have them try it but they don't do that sort of thing for free. There is nothing that I hate worse than taking a vehicle to the stealership and asking them to diagnose a vague problem. It gets awful pricey.

fordmantpw · Oct 8, 2015

N80 said:
Okay, so let's say it is a coil issue. Will the stealership have a tool that can detect this problem, in the shop, even when the ECU won't? With Japanese cars of this age this is not the case. If the problem doesn't happen when they run the diagnostic it will not detect it. In fact, on my old Maxima the dealership could not even tell me which coil was malfunctioning even when it did throw a code unless the problem happened when they ran the diagnostic. And again, it makes no sense to me that an ECU could possibly miss a series of three or four total misfires in a row and not throw a code. And if they are occuring, as you suggest, even in other gears and I only feel them when in OD, then that is even less likely.

But, I'm generally a pretty poor automotive diagnostician. So if the dealership can detect a latent coil issue with their equipment then I'll take it and have them try it but they don't do that sort of thing for free. There is nothing that I hate worse than taking a vehicle to the stealership and asking them to diagnose a vague problem. It gets awful pricey.

Honestly, I would not take it to a dealer, but a trusted mechanic. Much cheaper. And yes, they can be tested by using an ohmmeter.

Fortunately, there is an easy way to test the coil packs in your vehicle and make sure they're working as they should. You need to use ohm meter to test the coil pack for continuity. Make sure you have the approximate ohm values for the coil pack. To find this information, research your car's engine on the Internet or purchase a Chilton's or Haynes manual to find out what the mega ohms reading on the coil pack should be.

dusty3030 · Oct 8, 2015

N80 said:
Okay, so let's say it is a coil issue. Will the stealership have a tool that can detect this problem, in the shop, even when the ECU won't? With Japanese cars of this age this is not the case. If the problem doesn't happen when they run the diagnostic it will not detect it. In fact, on my old Maxima the dealership could not even tell me which coil was malfunctioning even when it did throw a code unless the problem happened when they ran the diagnostic. And again, it makes no sense to me that an ECU could possibly miss a series of three or four total misfires in a row and not throw a code. And if they are occuring, as you suggest, even in other gears and I only feel them when in OD, then that is even less likely.

But, I'm generally a pretty poor automotive diagnostician. So if the dealership can detect a latent coil issue with their equipment then I'll take it and have them try it but they don't do that sort of thing for free. There is nothing that I hate worse than taking a vehicle to the stealership and asking them to diagnose a vague problem. It gets awful pricey.

You don't have to take it to a dealership, you said you had a good scan tool, it may work and you can DIY, but any good independent shop should be able to do it as well.

Read this article, it describes your problem and how to diagnose.

MOTOR Magazine Article | MOTOR Information Systems

dusty3030 · Oct 8, 2015

Same article in PDF - has pictures in the PDF.

http://www.motor.com/magazine/pdfs/072011_09.pdf

N80 · Oct 8, 2015

Thanks Dusty. Excellent article. As it turns out, my scan tool is not as good as I thought it was. It does not give me a data log. It does check all the available OBD parameters but all you get is a green check mark if they are okay. It shows "Misfire Monitoring" as normal but as per your article this probably doesn't mean anything. I might be able to get an app that does give a data log but I haven't found one yet.

The article mentioned that the ECU will shut down the fuel injection to the cylinder that is misfiring to avoid damage to the cats. If what I am experiencing is, in fact, a misfire, it is only intermittent. Does the ECU shut down the fuel injection for limited times or until the problem is solved. If it kept it off I think I'd be able to feel that as a loss of power.

It also seems nuts that Ford designed a system that will detect misfires well enough to shut down the fuel injection and still not throw a code.

As far as checking the ohms, will this work for an intermittent problem? It would not for my Maxima. Testing of individual coils was normal until one of them failed altogether.

I have a trusted local mechanic. Mostly imports but he has done work on my other Ford. I assume he has the necessary diagnostic equipment. He is not a friend or anything and I wonder if he would be offended if I gave him that article when I took the truck in?

Checked with the dealership. The last transmission service was fluid change only. No flush. No filter change. Probably time to get that done anyway.

I guess if it is a coil there is no harm driving it anyway.

Starting to think it is time for a Nissan Titan! (Used. I do not buy new trucks).