Me again...

2004 ford ranger v6 4l

finally down to 1 issue - lean on bank 2

fuel trims on bank 2 idle at +21% and under load at 2500 rpm sit at +15% all sources tell me a vacuum leak. I sprayed every fitting i could get at and eventually gave up as it was going in for an airbag recall i had them diagnose the lean condition. They says its a leak in the manifold gasket - i changed that this morning and its still ‘lean’ trim at 25% now and under load at 5%

they probably had a sniffer but i dont and the fix didnt fix anything other than change the trim values better under load.

any ideas? I cant feel anything around the manifold or see anything coming out at idle nor anything underneath.

i did fix the evap issue, electrical connector corroded down the frame.

 

How many miles on this 2004 V6~4.0L~SOHC?
How many miles since Plugs+Wires+CoilPack changed?
How many miles since OxygenSensors changed?
What are the OBD2 TroubleCodes?
What are the ODB2 OxygenSensor signals doing?
RonD should have some expert ideas.

 

170k on engine
10k since plugs/wires/coil pack
no obd2 codes as yet
02 sensors are new, all operating within spec

the lean code stayed away when i put a new manifold gasket on that side.

Long term fuel trims on bsnk 2 ifle at +18% and under load +5%

bank 1 are idling -0.2% and under load +1% there abouts

id prefer the fuel trim to be lower at idle and i dont know enough to come to a suspect/issue

my own curiosity and mpg :) hardly getting 390k out of a tank

 

Since O2 are new they should be easy to swap around, just to take that off the table
"new" means NEVER EVER tested now-a-days, it no longer means "it works"

Yes, exhaust manifolds can suck air IN between exhaust pulses, O2 sensor can only "see" air(oxygen) so an exhaust manifold leak can cause "false" Lean
A false lean would cause lower MPG and spark plug tips on that side should be a darker color because they are actually running Rich

A vacuum leak on lower intake on that side can show as lean and higher fuel trims, but that's not a "false" lean so MPG shouldn't change much

Misfires can show as false leans, O2s only "see" oxygen, if a cylinder misfires then NO oxygen is used up burning the gasoline so that oxygen is dumped into the exhaust and O2 sees that as too much oxygen, so lean

Dirty injector tips drip fuel instead of spraying fuel, this causes a poor air/fuel mix so incomplete burns and lean O2 voltage
Seafoam or similar injector cleaner can clean the injector tips

 

4-5 cylinder plugs, i cant find the pic of the sixth but its the same condition

 

They look a little darker than they should, first picture for sure

Have a look at #1 or #2 just as comparison

 

Ok ill pull one out later today

 

-30 last night and -40 today.

im still interested in your ideas but freezing my nipples off isnt on my list today lol

 

ok do 1&2 are wet but i wouldnt say they were concerning. -38 out today and went for a drive down to 1/8 tank gas and just rolled over 300k so i watched the fuel trims and o2 sensors doing 110km down the road. Bank one steady under load at -7% and idles usually at -2% bank 2 idling at 14% and under load at 10% so not terrible. Im wondering if the manifold gasket is sealing better when warmed up...

going to seafoam the throttle body and treat a tank of gas to hopefully eliminate the injectors. If i pull a plug when its cold ive been told that if the threads are wet then they (injectors)are leaking. If leaking are they pooched? Or will cleaning resolve that?

The trims are better in the cold than the warm.. does that indicate anything? That manifold came with the replacement engine so i dont know the history i cant feel any leaks on it. After it connects to the Y pipe there is a dent in it that im unsure if it was designed like that for clearance or anything..

 

No on the cold or warm thing
Fuel trims are only valid once the O2 sensors are working, when they are heated above 650degF
So that takes a few minutes from cold start