Need help multiple codes thrown
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Member
Joined: Oct 2012
Posts: 49
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From: North Ga
Need help multiple codes thrown
I have a 97 f150 4x4 with 4.6 just started running rough smells like in runt fuel . The check engine light came on recently. It has about 10 error codes that I assume are all related to one common problem. It shows a miss-fire on cylinder 8, bank one and two O2 sensor, EGR valve, something about fuel mixture. The truck runs a little rough - sometimes a little shaky - and smells strongly of unburnt fuel (running rich?). Could be something simple or could be serious. It is not ERG Valve or DPFE or MAF Sensor or spark plug as I have changed those. Maybe valve issue, jumped timing, bad fuel injector, faulty wiring, or ?? Any ideas what else
Junior Member
Joined: Oct 2013
Posts: 20
Likes: 3
From: Mobile, AL
Cyl 8 Ignition coil? The rear coil on the driver side. Switch it with a different cylinder, see if the misfire code sets for the other cylinder. Could be a stuck open injector. Install a fuel pressure gauge, key on engine off, the pump will run for a second. If the pressure drops to zero in a few seconds you may have a stuck open injector.
Senior Member
Joined: Sep 2011
Posts: 419
Likes: 42
From: Minnesota
'97 with a 4.6 would be coil packs not coil on plug. Switching won't do much good. Maybe has a bad ignition wire. Most likely you have lean codes not O2 sensor codes. I see oxygen sensors thrown at vehicles all the time for lean or rich codes. You need to check actual data before condemning an O2 sensor. Shorted to heater circuit is normally why I have to replace them. A misfire will also show lean at the O2 because the fuel and air in a given cylinder didn't get fired. I'd start with fixing the miss then recheck codes after the repair and clearing the codes. See what returns.
Junior Member
Joined: Oct 2013
Posts: 20
Likes: 3
From: Mobile, AL
'97 with a 4.6 would be coil packs not coil on plug. Switching won't do much good. Maybe has a bad ignition wire. Most likely you have lean codes not O2 sensor codes. I see oxygen sensors thrown at vehicles all the time for lean or rich codes. You need to check actual data before condemning an O2 sensor. Shorted to heater circuit is normally why I have to replace them. A misfire will also show lean at the O2 because the fuel and air in a given cylinder didn't get fired. I'd start with fixing the miss then recheck codes after the repair and clearing the codes. See what returns.
Junior Member
Joined: Oct 2013
Posts: 20
Likes: 3
From: Mobile, AL
With wires this time.... lol.
This is what I do to identify an ignition miss on an engine with wires and not COP.
With the engine idling, pull the #1 wire loose from the plug, just barely, just enough for it to arc to the head and not the plug. This will cause a second misfire. The engine should shake like crazy, maybe even shut down. Put the wire back on #1.
Pull the wire from #8 just barely. Just high enough for it to arc to the head instead of the plug.... does it miss like crazy or was there no real change? If it has no real change, inspect your wire and coil for a failure.
This is what I do to identify an ignition miss on an engine with wires and not COP.
With the engine idling, pull the #1 wire loose from the plug, just barely, just enough for it to arc to the head and not the plug. This will cause a second misfire. The engine should shake like crazy, maybe even shut down. Put the wire back on #1.
Pull the wire from #8 just barely. Just high enough for it to arc to the head instead of the plug.... does it miss like crazy or was there no real change? If it has no real change, inspect your wire and coil for a failure.
Last edited by wyleone; Oct 28, 2013 at 02:44 AM.