I have a 98 with the 4.6l and 113,000 miles. It's been stuttering for a bit now, i replaced the plugs, wires, and pcv valve. The truck ran fine after that. Since the stutter and the check engine light comes on saying either bank 1 is too lean or cylinder 1 missfire (both trouble codes have been given) started I have replaced the oxygen sensors and coil packs within the last week. I have cleaned the Idle air control valve, TB, and MAF sensor (i used plastic safe sensitive electronics QD cleaner). Ford has performed their injector service 8,000 miles ago, I have run 2 bottles of sea foam through it since then, replaced the fuel filter and checked the fuel pressures. I haven't cleaned or replaced the EGR valve yet though. Any ideas? I'm starting to get really frustrated and might have to give in an take it to my Ford dealer. Thanks,

Brittain

 

WOW!! You've done quite a bit !! IDUNO, If it were me goin by experiences with my 98 - I've had to replace the upstream O2 drivers side and the DPFE sensor - when that screws up it sends your PCM bogus signals . It's a monitoring sensor and is known to fail.

Check your vac lines again especially on the back of your TB - a known collapse failure there.

Worse case senierial - it's your lower intake manifold gaskets that are leaking.

Good Luck!!

 

I had a severe exhaust leake which caused my lean issue so I would check that next if I were you sounds like you covered the rest of the basses I am betting its that gasket is fried or the flange bolts are gone and its leaking there big time. Good luck

 

My bolts rusted out on the drivers , One bolt finally snapped , But It was evident - You couldn't tell or can't tell sometimes if it's leaking by accelerating . That's when i could really tell I had an exhaust leak on my 5.4L . Doesn't hurt to check

 

Did you ever find out what the problem was? I am having the exact same problem, went through just about everything you have, and still having hte problem.

I have no idea.

Hopefully you are still on this board.

Thanks!

 

I had a heater hose clamp that had come loose just a little bit and had leaked coolant onto a plug and corroded it away. The service guys also told me that eh Bosch plugs I was running had been having issues in the 4.6L engines. Hope that helps.

Brittain

 

Was the plugs the had corrosion on them the two closest to the driver seat by chance?