p0171 p0174, pinging, maf?

[betard_foosier]

Hello, i've been dealing with a system too lean both banks, high idle ltft, misfire at idle, and a ping under load. Today, i unplugged the maf, and the idle barely changes, in fact it smoothed out a bit. The random lope was gone. Does that mean i habe a bad maf, or do i have a problem elsewhere in the ecu and the maf just shut the whole diag system down? The scanner shows the maf registering flow that increases with throttle, but idk if there can be other issues with a maf.

 

[john93rangerstx]

good the bad intake manifold gasket vacuum lines leaking spray brake cleaner around gasket vacuum lines some leaks u need smoke

 

[betard_foosier]

Well i replaced all intake gaskets last summer, and even retorqued today. Ive smoked the intake and found nada. I know its a symptom of intake leak, especially since the ltft goes down to single digits at higher rpm, but i cannot find anything. Can a sensor or computer issue cause the same symptoms?

 

[Sasquatch_Ryda]

what year? SOHC or OHV?

 

[V8RangerBoy]

High trims at idle are very suggestive of vacuum leaks.

What engine is this? Remember there are many other places to develop vacuum leaks besides just the intake gaskets themselves. Any air leak behind the MAF will act similar to this. Other common leaks are where the EGR tube goes into the plenum. I also see many vehicles with holes worn in the small plastic vacuum lines that go to heater controls and such, caused by rubbing on the plastic corrugated wiring loom tubing. The rubber tubing Ford uses for the EVAP system is also very, very prone to degrading and leaking. It sounds like you have a means of monitoring fuel trims - if so, plot short term trims and start spraying suspect areas with carb cleaner. When you find the culprit, the trims will drop into largely negative values.

 

[betard_foosier]

Sorry, 98 4.0 ohv. Ive done the propane, the carb cleaner, i can't find it. Is there ANYTHING else that causes high ltft at idle?

 

[1994Ranger$$$pit]

Maybe this will help.
I did some research when I had issues,but,I had only bank 1 lean and it was an O2 sensor.

http://rockledge.home.comcast.net/~rockledge/RangerPictureGallery/FuelSupplyManifoldGasketTSB.pdf

http://www.ebay.com/itm/FORD-OEM-FU...KE-GASKET-1995-2001-RANGER-4-0L-/160949324041