I am looking for a test procedure for the coil pack on a 5.4L '01.
Having hesitation/bucking around 1500 RPM in O.D. I have seen the problem noted, with varying degrees of success. This seems to the most suggested starting point to look.
An assistant is required. Have your assistant start the engine and put the truck in gear while holding brake depressed. You then disconnect the connector for the coil packs one at a time and then reconnect them and move on to the next COP. When the connector is removed you should notice a change in engine RPM and see the engine shake somewhat. The ones where you notice a change are good. If you don't notice any change it indicates the COP is bad on that cylinder. You might not get any P03XX DTCs and still have some bad COPs. I had #1 COP bad, but had no misfire DTCs.
Missing at low rpm in OD under light loads is usually a dead give away for a bad COP.
No code, no light.
It is a lean miss under the specific conditions.
The offending COP has shorted turns and cannot be found by a simple resistance test.
A dealer 'stress test' for output is the only way short of some luck.
Replacing all 8 also has a remote chance of still getting one bad new coil to confuse you. Saw it happen many times and been here in the past and learned.
The reason why this condition happens is a story in it'self if you really need to know.
Good luck. You now have the lead. Just find which one.
The fact that Ford can't detect it's own misfires shows their OBDII software has room for improvement. Having to do a stress test or load the engine down and remove the COP connectors means DTCs are NOT being set even though misfires are occurring. You wouldn't have to do those steps if misfire DTSs were being set. Setting misfire DTCs are supposed to help the technician get the car out the door faster. Without them you either have to do extra work or you start barking up the wrong tree as I recently did. I had misfires WITHOUT misfire DTCs. The DTCs I had were Lean Codes so I started troubleshooting them. When I couldn't find the source of the lean codes I went back to basics and worked directly on the misfires. That's when I found the bad COP on #1. Ford overdrives their COPs which contributes to their high failure rate. If you compare Ford to other brands you'll find they don't have the high failure rate of Ford because the other brands ramp up their coils more slowly rather than hitting them with full current as Ford does. These Ford COPs are going to continue to fail, but if I have misfires on a Ford in the future without misfire DTCs I'm going to look for a bad COP rather than something that could cause a different DTC.
The conditions that Bluegrass refers to will not set a misfire code because there is no hard failure of a coil. A misfire has to be repetative enough in a given number of engine revolutions for the misfire code to be set.
Let me give one anecdotal example of misfires that I believe should have set a misfire DTC, but did not. 99 F150 with rough idle and very poor acceleration. The misfire was bad enough that the truck couldn't get out of its' own way yet no misfire DTCs were set. How bad does it have to get for the P03XX DTCs to go set. I have a truck(not Ford) with a big(aftermarket) camshaft in it and on cold mornings I get a misfire DTC because of the lopey idle even though the truck is idling good and accelerates smoothly. I can guarantee with a truck running as bad as this F150 was running the customer is going to bring the truck in for service even though the SES lite is not illuminated.
I realize OBDII strategy monitors the CKP and CMP and has no way of knowing if the misfire is due to a bad COP or the spark plug or even in the case where there are spark plug wires a wire that is disconnected. I'm saying that Ford strategy does set misfire DTC or at least I don't see them when there are misfires and bad ones at that. If GM can dectect a lopey cam on a cold morning why can't Ford detect a real misfire on a stock engine that has a bad COP?
I suppose the simple answer to that is the COP hasn't suffered a hard failure in the sense of open or completely shorted out. I assume that either of these cases would surely set a misfire code. The COP is actually failing in as soft failure mode with one or two turns of the coil shorted out, letting it continue to work except under high engine loads when it's output falls off and the intermittent misfire occurs. that is why a stress test is used to illustrate the weak COP.
The F150 I'm talking about had misfires at IDLE(very low load) and during full throttle acceleration(WOT-heavy load). Under this theory I can see the misfires not being detected at idle, but when accelerating from a dead stop which is heavy load the misfires should have been detected. The ECM anticipates the pulses coming from the CKP and CMP using engine speed, load and other factors. When those pulses don't arrive within a certain "window" either your on a very bumpy road(washboard) or you're having misfires. I'm beginning to believe the "window" for Ford is just barely open if at all.