misfires

houdini_dan · 03-25-2008, 09:22 PM

My 97 f-150 4.6 triton misfires. the check engine light comes on and the code reads either multiple cylinder misfire or cylinder 1 misfire. I've changed the plugs And no change. I believe the wires are good but have dont know how to check out the coils. Any suggestions?
Thanx

graham567 · 03-27-2008, 09:33 PM

Usually if its a constant misfire you can unplug the electrical connectors on each coil when the engine is running and if there is not a change in rpm's then that one is misfiring. You can also go buy a coil tester from o'reilly auto parts or somthin. Im having the same problem with the misfires and just cant figure out why.

kycowboy2 · 03-28-2008, 08:56 AM

The Dealer can run it on their computer and check it out for a continuous miss fire and run special test on your coils that their WDS test equipment is designed for that way you aren't replacing unnecessary parts , I understand everyone is afraid of their dealer but it's normally cheaper than replacing all the coils .
John

phantom_smack · 03-28-2008, 09:03 AM

I believe he has 2 coil packs and wires,you can place the plug wire near some metal and start it or yo can use insulated pliers and pull it off the plug while its running and listen for the spark popping

houdini_dan · 03-28-2008, 10:12 PM

i did some more testing today and I found that I'm gettin spark. I think its a fuel problem. either bad 02 sensor or somethins wrong with the injectors. does that sound logical?

doug 351 · 03-29-2008, 08:02 PM

I wouldn't think that injectors would cause misfires, and o2 sensors usually mke it run like crap and use a lot of gas, but not necessarily misfire. IMO, you have an electrical problem. "Getting spark" will not diagnose your problem, as it could be getting spark occasionally but not at the right time. You have to follow the earlier recommendations of pulling one wire at a time while it's running and listening for no change with one wire pulled.

houdini_dan · 03-30-2008, 01:21 AM

could my problem be that the spark plug gap is incorrect?

phantom_smack · 03-30-2008, 08:58 AM

o2 problems usually a result of another problem,injectors can cause a misfire but usually cause a runs rough concern

maxxflow · 03-30-2008, 09:52 AM

Run a compression test to see if you have good compression at the cylinder in question. Compare it to factory spec, and if lower than the min. accepted value for psi, you need to have your internals in cylinder one checked. Damaged valves of the cylinder in question can also cause a misfire. I hope the culprit is what the other members have been posting about. If all those fail, try the compression test.