Super Lean E150
at idle I am +20 both banks I am around +15 off idle. ive checked fuel pressure, checked over and over for vacuum leak systematically blocked off lines used some machine sprayed brake clean. i can only find a small leak in weep hole of EGR diaphragm doesn't make a big difference when I block it off. checked for exhaust leak nothing MAF reading is on par around 4.5 grams at idle. Replaced plugs idle slightly rough i was wishing on a star hoping maybe we had some misfires not getting counted not uncommon with ford o well needed a set anyway. O2 seem to respond well plus for both to be skewed would be unlikely. Im sure im missing something… hell i feel like i am… any suggestions thanks
While checking fuel quality, also check the fuel for Alcohol content. Is it E85?
Is the air cleaner/air filter housing installed. On Ford vans, if the air filter ‘EGG' housing is open, the engine cooling fan will mess with the MAF.
Check fuel quality, Ethanol content. Also double check PCV system. Rotted hoses, things of the sort.
Does it have the correct style air filter installed.
Hi Derrick, Replace the inline fuel filter would be the first thing to address. After that test fuel quality, volume and pressure. Being a Ford 4.6 the PCV soft hoses are bad about collapsing and sucking air, this can be hard to hear and find if the vans engine cover is still in place.
Lean at idle is not a fuel supply issue.
Ck fuel pressure and volume. Do the 02s show rich at WOT, when driving thru the 1st to the 2nd gear shift.
Maf drive full throttle under load test ( adhere to safety precautions ) should flow 184 grams per second , if maf flows correctly with the + trims you show (also graph post cats o2 sensors when performing maf test to confirm lean mixture) fuel volume delivery and or or fuel quality is the next test. (misfire monitor will most likely suspend if under ¼ tank)
If it worse at idle and gets “less lean” with throttle opening and is normal under load, you almost certainly have a vacuum leak.
I’ve had a Ford with good g/s that was also lean, what I found was that hertz where at 120 at sea level when they should be at around 159. i would recommend to check how you hertz and compered them to specs depending of the level you are located
Derrick So many outstanding ideas in the thread so far. Since you have indicated lean at idle, does freeze frame support this? (probably under generic, you'll get one freeze frame data capture). Do not clear codes (or you'll have to accumulate drive cycles again), bring engine speed up to about 2,000 RPM. Do the LTFT1 and 2 approach zero?. If so, I would agree with most in the thread, the…
I have experienced the smoke machine push and seal the elbow but engine vacuum opens it back up
I'll second the vacuum elbow. I've also seen the dipstick tube break from the bracket and create a slight vacuum leak.
Is 4.5 g/s at idle really ok? I believe the g/s at idle should be roughly 1.25% of engine displacement. This is not exact, but more a general rule of thumb. If I see less than engine displacement I start looking at the maf. What does it do under load? Do the o2's maintain 800mv on a hard acceleration? VE test would be in order. What does the load say on a WOT stab at the 1-2 shift?
I have seen a rubber vacuum fitting on the back of the engine with a hole in it or popped off the vacuum port. Spray some brake cleaner in the back of the intake manifold just above of the bellhousing.
That was my initial thought as well. Seems kinda low. I’d be curious if it’s only lean at idle like the other guys stated.
O2's monitor would probably fail before those trim code codes if those were issue set, unplug MAF see what changes , MAF & TPS should mirror each other graphing … purge valve also in the equation at idle …
Robert I forgot about EVAP circuit and purge valve. But I wonder, if the purge valve were allowing fuel-tank-rich vapors, wouldn’t it run rich? I’m probably not thinking straight. Your thoughts?
Initially that's true but purging uses up fuel vapors quickly & who knows might sticking solenoid sucking fresh air , it's just on the quick check list blocking it off & eliminating a possible cause if its sitting there bleeding internally like a blown PCV elbow .
Does this van have EGR? If so can you check the pipe temp and make sure it’s not flowing at idle.
Wouldn’t that make it rich, since your are displacing the air in the combustion chamber with spent exhaust gas?
I don’t think it will make it rich or lean. I think the trims would be normal since It has a MAF. It is likely not the issue with Derricks van now that I think about it.