Okay guys I really need your help on this one.... my engine is running rich and I'm not sure why, I've already replaced all the oxygen sensors replace piping for the PCV system. I'm kind of getting sick of just replacing random things to see if it would help. every once in awhile I get a bank one lean code on Startup. I'm just really curious what this could be any thoughts would help.

1997 Ford F150 Lariat 4.6. list of things I have replaced all of the oxygen sensors front and rear. Cadillac converters mass air flow sensor PCV system


Mil status off
ABSLT TPS% 19.2
ENG SPEED RPM 838
CALC LODE 27.5
MAF (LB/M) 0.73
COOLANT (F) 124
IAT (F) 37
ING ADV 14.0
ST FTRM1 5.6
ST FTRM2 7.8
LT FTRM1 23.4
LT FTRM2 19.5
VEH SPEED 0
FUELSYS 1 CLSD
FUEL SYS 2 N/A
O2S11 0.85
ST FTRM11 8.6
02S21 0.395
ST FTRM21 7,8
02S22 0.525
OBD2 STAT CA

 

How do you know it's running rich?

Your coolant temperature is too low, it should be around 190 to 210.

 

Long-term fuel trims are high and I keep getting the too lean code on bank 1

 

I'd say you still have a vacuum leak... the fuel trims are trying to compensate for the unmetered air by running more fuel.

Do you have a the alum intake or plastic?

 

I have the aluminum one is there any definitive test that I can use to tell me where it's leaking at I tried some but they don't work

 

Did you miss what I said about the coolant temperature? If it thinks it's that cold it's going to run rich.

 

No I didn't I think the temp sensor might be part of the problem but it still doesn't explain why one fuel trim is higher than the other

 

One of 3 things - it wasn't warmed up when you took those readings, thermostat is stuck open, or the CHT sensor that feeds the PCM is bad.

All 3 of these conditions are going to cause it to run rich.

 

Well you're right when I took those readings it was about a 20 degree day in central Pennsylvania..... I don't believe it's the thermostat cuz one of the first things I did when I got the truck last year is I replaced it I've never gotten the code for CHT sensor and I hope to never because it looks like a real bear to get out.... that set of data was more to demonstrate that no matter what temperature it's in the fuel trims are relatively the same all the time at ldle.

 

Doesn't matter how cold it is outside - the engine should be running at 190 when warmed up. Go drive it for at least 10 miles then grab another set of data.

 

Agreed with GLC that a faulty CHT or poorly functioning thermostat can make fuel trims high,
and a longer drive and retest is needed....your 1st post sees only coolant temp at 127*.

but wouldn't the fuel trims be more balanced side to side if it is a weak t-stat or CHT?? or aren't they that far apart?

 

Seems to me this is a good place to employ the good simple procedure I've seen GLC suggest before to eliminate the vacuum leak possibility. (It appears @MaxOverdrive has a scanner).


Monitor live data for those fuel trims while running an 'UNLIT' propane torch all around the IM, EVAP solenoid, PCV, - and everything. You hit a vacuum leak - you will see it reflected instantly on the fuel trims. Works like magic!

 

Okay guys I had a little bit of time today to take new readings and helper to monitor the Craftsman scan tool data for the propane test. it seems like I have a little bit of a vacuum leak on the number four cylinder intake runner

PS The readings were taken immediately after a 20-minute ride home so that reflects the normal operation of the truck and normal temperature readings


Mil status off
ABSLT TPS% 19.2
ENG SPEED RPM 699
CALC LODE 24.3
MAF (LB/M) 0.50
COOLANT (F) 181
IAT (F) 55
ING ADV 13.0
ST FTRM1 1.6
ST FTRM2 -2.3
LT FTRM1 34.4
LT FTRM2 19.9
VEH SPEED 0
FUELSYS 1 CLSD
FUEL SYS 2 N/A
O2S11 0.830
ST FTRM11 0.8
02S12 0.475
02S21 0.025
ST FTRM21 0.8
02S22 0.480
OBD2 STAT CA

 

That temperature is more like it.

Sounds like it's time to pull the intake and check it for cracks, etc.

 

Take your fuel trim readings again (with engine at normal operating temp) but at 1500 RPM and then at 2500 RPM and note what you fuel trims are at those two RPMs. It looks like you only have been taking your readings at idle.

Typically if your fuel trims go lower at higher RPMS then you have a vacuum leak some where. If the fuel trims stay high at the higher RPMs, as they are at idle then you may have some sort of fuel pressure issue or injector issues.