I have an extended cab 1997 ford f150 4x4 4.6L 5 speed manual transmission.

Back in December the check engine light came on and my engine started feeling like it was mis-firing. It seemed to happen pretty spontaneously but it is pretty noticeable now. The check engine light flashes when possible “mis-fire” is occurring.

I have noticed that the misfire seems to be most severe and noticeable while going uphill/when engine is under heavy load. I will hit a hill in first and I can feel the misfire but I am able to overcome it because I can still hit high rpm and the mis-fire seems to stop around 2500+ rpm. Then I shift to second and the mis-fire comes back due to the lower rpm and then seems to stop around 2500+ rpm again. If I were to hit third at a low rpm the engine would definitely lug out hard.

The misfire is also very noticeable when starting from being stopped on a hill, sometimes feels like it’s almost about to die (severe lack in power).

I picked up a new fuel filter today and hopefully I will be able install it this week to see if it makes a difference.

Other than that I’m thinking I might be looking at fowled spark plugs/failing wires, dirty injectors, failed 02 sensors, plugged cat, and the list goes on.

Any more ideas?

 

Yeah,
check the code left in the computer!!!
Don't just start throwing parts at it.

 

Ya, unfortunately I don't have a code reader right now cause I'm lookin at spending 150 bucks + to get one but I guess it's worth it in the long run to have one around anyways.

 

Don't know where you are, but here in WA you can borrow one at O'Reilly's or AutoZone. At the local O'Reilly's you give them your DL to hold until you bring the unit back. We were even given directions on how to use it. Went to the parking lot, pulled the code, wrote it down and returned the device. Also, you can find code readers for under $100.00 if you look around.

 

Ya, I'm in Powell River BC... besides Canadian Tire we have a small napa auto parts store for auto parts and thats about it... it's a pretty small town...

 

I have the 5.4 automatic. I thought I had a misfire and the SES light came on. We changed the plugs and reset the SES. Drove a while, SES light came back on. Reset it without doing anything. 24 mile later it came back on. Put it on a code reader and got P0135 (bank 1 sensor 1). Replaced the O2 sensor on the passenger side on Saturday. Went ahead and replaced the fuel filter too. Truck runs great now. Didn't have to replace any COP's. I'm gonna replace the other O2 (bank 2 sensor 1) when it comes in. Not to worried about the downstream ones. Should be good for a while now.

 

Right on... correct me if I am wrong but from what I have read and seen while tinkering, having the 1997 4.6L, I won't have the Coil On Plug configuration, instead I will just have two coil packs (one on each bank). I'm pretty sure from my own reading that COP doesnt make an appearance until 99?

I'm hopin to pick up a code reader soon now anyways though so that will shed more light on the problem.

 

Yes, you should have 2 coil packs in that truck.
Not COPs.

 

My guess - Wires.

I had this happen multiple times. Multiple because the stock wires went and I bought "Premium" auto-parts store wires... two different makes/sets...

Finally, for my fourth set of wires I took the advice from all the other guys here and bought real Ford wires... and I finally don't have a miss.

Sometimes you'll find that a heater-core hose leaks right on top of a plug-hole on the passenger side of the truck, and of course that causes its own problems, but if that's dry and you've got a 1997 with the original wires... then wires is my educated opinion.

 

Right on thanks for the input... I changed the fuel filter out and it seems to have helped quite a bit but the misfire is not gone completely so I guess I was always looking at two issues

 

Big-Red, I've met a couple of the instructors from the automotive department at the college in Powell River and they're good guys.
If you stop in there the students might be able to scan it and/or diagnose it for you.

 

Auto Zone here in PA loans them out. I actually had the guy come out in the parking lot and read them off.

Misfire cylinder 3

Much better than throwing 8 new plugs/COPs at it - especially cyl 4 and 8 buried deep.