I have a 2001 E-450 with a 6.8 liter. It has codes PO302,PO303 and PO171. Can someone help me on what these mean and what to check for?

 

Well here is the info that I found...

P0171 -- System Too Lean (Bank 1)

P0302 -- Cylinder 2 Misfire Detected

P0303 -- Cylinder 3 Misfire Detected

Ok...for the two misfire codes it could either be the COP (coil on plug) or the boots. For the P0171 code...I would fix the other two codes first...and see if that cures it.

Good luck...


biz

 

Actually, that's bass-ackwards.

Fix the LEAN condition FIRST. The misfires might be related.

Check for vacuum leaks, any leaks in the intake tubing after the MAF, clean the MAF, and change the fuel filter. Clear the codes and see if they come back.

There is either air getting into the system after the MAF (unmetered air) or you don't have enough fuel pressure (that's greatly oversimplified).

If the lean code comes back, check the fuel pressure, especially under load.

 

I have a 98 E-Superduty Chassis in a Class C motor home tossing the same codes.

This coming Saturday I am going to go through the same drill, remove the engine cover, and inspect everything in hopes that I missed something the first time. This based on Krewat's advice a month back.

When I had a spark plug blow out and during the repairs made by Blownoutsparkplug.com, they checked the small horseshoe shaped knock sensors on top of the intake manifold (one on each side) to make sure they are tight. Apparently he has seen a few loose and not listen properly. Mine were tight so no help there but you might check them.

I will also change the fuel filter and go from there.

I did clear up this condition once years back by clearing the MAF sensor but this time it was not dirty and cleaning it did not affect the condition at this point anyway.