ok i have a 97 explorer 5.0 awd, 3 days ago it started to misfire.i cleared the codes and then took it to autozone and the codes were p0303 and p0171 (indicating misfire on cyl. 3 and bank 1 running lean) so i bought a new plug wire ( o.e. type ) and 8 spark plugs ( NGK platinum ). i switched them rite out and the #3 plug wire. i then cleared my codes i started it up and still a misfire. i waited till the next day and drove it to autozone about 8mins away at 30mph. the codes now read p0301 p0303 p0171 p1131( misfires on cyl1 and cyl3 and bank 1 lean and bank 1 at its lean limit) so i bought 2 more sparkplugs and 2 more plug wires. then cleared the codes and started it up and it was still missing and chugging when on the throttle till about 1500 rpms and then its reasonably smooth. so i switched out the coil pack for those cylinders and still a misfire with the same codes as before 303, 301, 1131, 171. i then began to listen to the injectors and they sound very similar to one another. i ran some seafoam cleaner through the gas and did some driving around for a few hours plus some idle time with no difference. also the new plugs are black and smell of fuel after short periods of time. i also checked the firing order in case of my own error and it was good and then i pulled the boot from the plug while running and inspected the spark ark and it was strong. i'm actually wondering what my next steps should be? should I?
swap cyl 1 and 3 injectors with 2 and 4?
spray the intake manifold in search of vacuum leaks?
check and clean the pcm connection?
Thanks and p.s. i like shinny new parts under the hood

 

If you were having an ignition misfire and the rest of the systems are working, you would not expect a code for a lean condition but rather a rich condition since the spark plug would not be igniting the raw fuel in the combustion chamber. If the lean code is real and occurred the same time as the misfire code, I'd be looking more at the fuel injector and the fuel injector wiring. Do you have an oscilloscope or a noid light that you can use to confirm you are getting a trigger to the injector? When you removed the spark plug from cylinder #3 was it wet with unburned fuel?

-Rod

 

well i pulled the top end off today and pulled out the injectors. on #3 cyl. the injector was a little dirty on the bottom side compared to the rest and when i shook it there was some fuel that came out. the others didnt really drip so i figured i will get another tomorrow. as far as the intake gaskets (upper and lower) they were not in great shape so im switching them out tomorrow as well. i didnt have a test light so i used a screwdriver to listen to the injectors and they sounded identical to one another. i also checked the wiring at the pcm and it was spotless. the plugs (1 and 3) smelled of fuel and black at the ends but weren't really saturated with fuel. im putting it back together tomorrow with 2 new injectors and new top end gaskets. there was also another few things i noticed though, the upper intake manifold has 6 bolts and the front 2 were torqued down (breaker bar) and the other 4 were much less tight (3/8 rachet)? also i had a bad egr vacuum hose and i apparently had a pin hole coolant leak on the lower intake gasket. leaking out of engine not in. so if its not any of that (injectors,gaskets) it must be the vavles?

 

I suspect you'll fix your issue with the injectors, gaskets, and fixed vacuum hose(s). Burnt or leaky valves could be identified with a compression test.

-Rod