I have an issue with my 2001 Ford Econoline that I can not seem to figure out.. the engine light came on, and the code reader was telling me the system was too lean in bank 1 and 2. I had all of the oxygen sensors replaced, the mass flow air sensor cleaned, and new air filter. After a little bit, the light returned with the same error, only after the van started to have severe difficulty starting.

This eventually over time ruined the battery, and after replacing the battery, the engine light was gone. Then when starting the van, I would get several small backfiring happening under the hood when pressing on the gas. After a few days, when I am at a red light and the light turns green, it takes so long for the van to cross the intersection that I have people honking and threatening me, and the light turns yellow before I'm half way through.. once I start going, the van will rarely go above 30 miles an hour, and constantly backfires 10 times every 3 seconds, in irregular intervals.

I pulled the doghouse out, located the spark plugs, and changed all 6 of them thinking this was the issue.. some of them in pretty bad shape. However, the van still has the exact same problem with the backfiring and driving.

Since changing the battery, the engine light has never returned, and using the obd2 readers bring back no current or pending codes. So I'm at a total loss at what to do now.. should I change the coils now? Is there a way to test the coils to see if they're even the issue? I'll also mention, so you don't think this is the issue, I changed each spark plug one at a time, never mixing the plug wires or disrupting the firing order... so that's not the issue.. but I'm suspecting the "system too lean" error has something to do with the backfiring issue?

Thanks for any suggestions!

 

Hi Richee,
You didn't say anything about the fuel filter. If you decide to replace it , make sure you relieve the pressure in the fuel system before attempting any repairs there. One way is to pull the fuel pump fuse while the engine is idling and the engine will run out of fuel and also remove most of the pressure in the fuel system. When you remove the filter check what comes out of it . You will need a special tool to relax the fingers that retain the lines on the filter, worth the investment. See what comes out , could be, nothing but gas , or water or junk. Let us know what you find, thanks.