Hi Folks, Subway Trash here with my 98 4.0 XLT 4X4Danger Ranger. NEED HELP!

[SubwayTrash]

Why is it when I hook my MAF UP I lose power and it won't idle?
It's brand new

 

[RonD]

Welcome to TRS

If you have an ODB2 reader reset computer, clear its memory
If you don't, unhook negative battery cable for 5 min to clear computers memory

When you install a new sensor, or anything, on an engine with a computer you should clear its memory

Why did you change the MAF sensor?
Were there running issues?
Were there any codes and what were the exact code numbers?

 

[SubwayTrash]

Welcome to TRS

If you have an ODB2 reader reset computer, clear its memory
If you don't, unhook negative battery cable for 5 min to clear computers memory

When you install a new sensor, or anything, on an engine with a computer you should clear its memory

Why did you change the MAF sensor?
Were there running issues?
Were there any codes and what were the exact code numbers?

 

[SubwayTrash]

That's what my OBD2 was saying with O2 sensors

 

[SubwayTrash]

Welcome to TRS

If you have an ODB2 reader reset computer, clear its memory
If you don't, unhook negative battery cable for 5 min to clear computers memory

When you install a new sensor, or anything, on an engine with a computer you should clear its memory

Why did you change the MAF sensor?
Were there running issues?
Were there any codes and what were the exact code numbers?

I can pull codes again in just a sec

 

[SubwayTrash]

I can pull codes again in just a sec

P0102
P1506
P0135
P0136
P0141
P1131
P1151
P0300
Wow didn't know I had that many codes.

 

[RonD]

P0102 Mass or Volume Air Flow Circuit Low Input
Means MAF sensor is dirty or air filter is
There is a large air tube from air filter box to upper engine throttle body, that tube needs to be air tight, sealed, no cracks or leaks
If its not air tight then you can also get this code

P0135 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0136 02 Sensor Circuit Malfunction (Bank I Sensor 2)
P0141 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
Check fuse 13 in Engine Bay fuse box, 15amp fuse, its blown
OR
You have some melted O2 sensor wires, or both

P0300 Random/Multiple Cylinder Misfire Detected
Clean spark plugs, but not a big deal.....................yet

P1131 Lack of Upstream Heated Oxygen Sensor Switch – Sensor Indicates Lean – Bank No. 1
P1151 Lack of Upstream Heated Oxygen Sensor Switch – Sensor Indicates Lean – Bank No. 2
Check fuse 13

O2 sensors only last 12 years, these are the ONLY sensors that wear out
If you don't know how old they are replace all 3 O2 sensors


P1506 Idle Air Control Overspeed Error
Means engine is idling too high and computer can't lower it
Could be because of an air leak/vacuum leak
After engine is warmed up, unplug the 2 wire connector on IAC Valve
Idle should drop down to 500-600 barely running, or engine may even stall, either is good it mean no vacuum leaks
If idle stays high then you have a leak OR IAC valve is stuck, clean it and retest

Vacuum leaks can/will cause MAF sensor codes, O2 sensor codes AND misfires

Ford OBD2 code list here: https://www.therangerstation.com/tech/obd-ii_trouble_codes/

 

[SubwayTrash]

Well there's the kicker I don't have any of the O2 sensors installed have exhaust that a custom built with a Flowmaster on back also has a cold air intake installed with mass air flow in it. The issue had started before I done all this it was losing power wouldn't hardly get past 3,000 RPMs and then I unhooked the mass air flow sensor truck started running great and I'm just trying to make it back right because it's running very very lean will not idle. Also I have coolant going who knows where and and thinking maybe my coolant temp sensor is bad as well I know that will make it run lean I'm really at a loss I think I've changed every sensor and still nothing

 

[RonD]

Yes, I do believe it won't run very well the way it sits now

All 1986 and up Rangers came with cold air intake, just FYI

MAF sensors need to be same as stock, for engine size and computer, as they only read a % of the air flowing thru them, like 13%, so data from MAF is multiplied in the computer to get the corrected "WEIGHT" of the incoming air
MAF sensor's purpose is to weigh the incoming air, computer already knows "how much" air is coming in, its a 4 LITER engine, what it doesn't know is how much that air weighs

Gasoline engines use 14.7:1 air:fuel ratio, a WEIGHT RATIO
14.7 pounds of air to 1 pound of gasoline
14.7 grams of air to 1 gram of gasoline
So air weight is very very important

All EFI(fuel injection) computers need working O2 sensors
They can run without them but not great

With no O2 sensors you will need to leave the MAF sensor unplugged so computer never goes into Closed Loop operation

An engine will ping/knock when its running Lean, sounds like a diesel engine
Does it ping/knock?
If not then its not running Lean, probably too Rich, which has much lower power than too Lean
Pull any spark plug and look at the tip
Light brown means good air/fuel mix
Darker colors are Rich mix or oil is leaking in

Best bet is to add 2 upstream O2s
If you can weld then you can weld the bungs on as close to exhaust manifolds as practical
Like these: https://images-na.ssl-images-amazon.com/images/I/511s-terbqL._AC_UL600_SR600,600_.jpg

If you can't weld then you can use Strap on O2 bungs, like these: https://www.efisystempro.com/image/cache/catalog/ProductImages/7101430x-1-1000x1000.jpg
Or these: https://www.aemelectronics.com/sites/default/files/product_image_product_sections/aem_neweld_o2bung_0.png

You should have a Cat converter as well and a 3rd O2 but your choice

ECT(engine coolant temp) sensor will throw a code if its bad, and you can't use it any case until you get the upstream O2s working

You are running in Open Loop now, this means computer is using air/fuel mix tables in its memory(factory tables)
They are made to be used on cold engines
Once the O2 sensors are heated up above 600degF the computer switches to Closed Loop and calculates air/fuel mix on the fly, in real time

With no O2 sensor feedback that won't work well, lol

If you unplug the MAF sensor computer will stay in Open Loop, which also ain't great after engine warms up