Why is it running lean.

I have a 02 2.7. All 4 plugs are white. Which is telling me the truck is running lean. Plus it is pinging. I can not figure out why it is running lean. It has new plugs and fuel filter. The computer is not putting out any codes. I was thinking it was the mass air flow sensor. I do not want to just replace if that is not it(that sucker cost $150). Any ideas or something to look at. Thans for the help.

 

Clean the MAF and throttle body, then reset the ECU via battery disconnect. Also check for cracked vaccum lines with carb cleaner(RMPs will rise if leaking.) ONLY use throttle body cleaner on MAF and throttle body. Carb cleaner will F-up them. Vac lines are after them and will not be affected.

 

x2....did you replace the plug wires with the plugs? Is the air filter new? Maybe a professional fuel system cleaning would help (i.e. could be a clogged injector, valve, etc). Keep up with them by using gumout every oil change.

 

I did not see any plug wires. Unless you are talking about the coil that sits on top of the plugs. Them sucker are a $100 each. I was not going to change them if I did not have to.

 

Only replace the coils when bad. Replace the boots when you replace the plugs.

 

ok, wasn't sure if the 02's used a coil on plug.

 

Just a thought the fuel pump could be weak or might have A piece a dirt or grit from the fuel. What grade of fuel do you run. I had a 98 that would act crazy on anything less than 93. Did you try some good fuel cleaner yet?

 

It should run fine with 89 octane. Check your O2 sensors, plugs, wire, and maybe run a can of Seafoam through it.