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2.5L ('98-'01) im gonna do a carb cleaner spray vacuum leak test


youngbuckwithapickuptruck

Well-Known Member
Joined
Oct 7, 2021
Messages
124
City
california
Vehicle Year
00
Engine
2.5 (4 Cylinder)
Transmission
Manual
Tire Size
stock
i have check engine light code on: p0171 bank 1 running lean
i tried the cigar smoke test twice, no smoke
i tried propane spray test no results
then i was told use carb cleaner cause it is way more volatile and i will be able to hear the idle change easier.

soooo.... i know this can catch my car on fire.
1. dont spray on an area so long that fluid pools up, then heats up and then ignites
2. run the test on a cold engine
3. keep a fire extinguisher handy,
4. i cant find any vacuum diagrams and am having trouble identifying where exactly are all my vacuum lines, halp???
5. also i imagine the leaks are most likely to be at the connection ends of each vacuum line, ya?
6. im reading that some vacuum lines connect to the brake system. is this the case with 2000 ranger?
any other tips, please?

i asked a shop if they would do a vacuum leak test and they said they could only do a check engine light diagnostic which would be $160 or more, depending on how long it took. i suppose i could also ask the ghetto shop down the road how much for a vacuum leak test.
 
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I've done it many times on hot engines. I'd suggest using a spray bottle of water to test your plug wires first, though.
 
"I'd suggest using a spray bottle of water to test your plug wires first, though. "
test my plug wires for a vacuum leak using a spray bottle of water?
 
No, when it's dark if you spray the spark plug wires with water it'll make it spark easier and brighter and is a reasonable idea

Other things that can do that are a worn O2 sensor or a dirty mass airflow sensor. I would probably grab a $7 can of MAF cleaner (don't use other stuff other than probably electrical parts cleaner), but a misfire from spark plugs is reasonable other than that basically means two plug wires aren't missing with a dual spark DIS system...

I got the same code on my '97 a few weeks ago, the MAF looked clean but the O2 sensor looked old and at 173k miles it was time, turns out it was a Motorcraft sensor with an F7 part number so it was original... $40 for a new sensor wasn't bad, the original even came out with an open ended 7/8" wrench somehow... I started easy, an actual O2 sensor socket was plan B. Oh, and the code went away
 
"I'd suggest using a spray bottle of water to test your plug wires first, though. "
test my plug wires for a vacuum leak using a spray bottle of water?
No, it would find any spark leaks before the carb clean blows up in your face.
 
"No, it would find any spark leaks before the carb clean blows up in your face"
ive watched a few videos on how to do carb cleaner vacuum test and none of them mention this. nor do the comments. ty.

I have a can of brake cleaner that is almost empty
will throttle body cleaner or parts degreaser also work for this test?
 
water bottle test
https://www.wikihow (dot) com/Test-Spark-Plug-Wires
"Spray down the spark plug wires to look for arcing. Fill a spray bottle with water and spray all along the wires. You will want to focus your spray near the boots that attach to the spark plugs to see if any arcing occurs there. If arcing is found at the boot near the spark plug, turn off the engine and inspect the boots further. "
soooo what does arcing look like? a flash of light? can this be done during the daytime? do i also spray around the coil pack? i assume this test is to be ran while the engine is running, yes?
 
okay, so i tried looking over the vacuum diagram this time and just started looking up google image of every term i did not understand. that search lead me to the "EVAP SERVICE PORT" so i started wiggling the hoses, and the rubber elbow just slid off the EVAP SERVICE PORT and also very easily came off the yellow vacuum line it was connected to. this hardened rubber elbow may very well be my issue. where do i find a replacement for it, as it does not want to hold tightly to the EVAP SERVICE PORT or the yellow vacuum line
 

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i am still confused as to what is
CCO,
+VENT SOL V,
CAN
i was able to google all the other terms .
I also noticed the vacuum diagram leads to the fuel pump assembly. could the vacuum leak possibly be from fuel pump replacement by a sloppy mechanic? after he replaced my fuel pump 3 years ago, i got a check engine light for a leaking hose between my gas cap and fuel pump.

ALSO, what is this big ball thingy? could this be a source of vacuum leak

I am novice mechanic trying to teach myself how to do this :0
 

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ALSO
code scanner says my 02 sensors are in 'open loop'
should i replace 02 sensors again?
recently I had replaced my upstream or downstream, i cant remember, and it started throwing a code so i put the old 02 sensors back in and that CEL code went away. (although p0171:running lean stayed)

someone somewhere said "its cause you bought bosch sesnsors and half of them fail"
ima order two new ones, only 75 bucks. should i get denso sensors this time?
 
i am still confused as to what is
CCO,
+VENT SOL V,
CAN
i was able to google all the other terms .
I also noticed the vacuum diagram leads to the fuel pump assembly. could the vacuum leak possibly be from fuel pump replacement by a sloppy mechanic? after he replaced my fuel pump 3 years ago, i got a check engine light for a leaking hose between my gas cap and fuel pump.

ALSO, what is this big ball thingy? could this be a source of vacuum leak

I am novice mechanic trying to teach myself how to do this :0
The vacuum line runs to the vapor management valve -VMV- not to the fuel pump. The VMV is likely on the frame near the tank. Any vacuum leaks could set lean codes, if you have one loose fitting hose I'd check the rest. The "downstream O2" is actually the catalyst monitor, PO171 would be coming from the O2 ahead of the cat. You can check the O2 ground easily and without spending a dime, we had an independent garage bring us an F150 with a lean code after he'd replaced the O2 five times. The tech fixed it in minutes by cleaning the corrosion off the O2 ground.
 
You can check the O2 ground easily and without spending a dime,

i found this guide from
it reads

  1. You will need a 10-megaohm impedance digital voltmeter for testing the o2 sensor. You should set it to the millivolt (mV) DC scale.
  2. Now start the car and let it run until it reaches operating temperature. This may take up to 20 minutes.
  3. Once you have reached operating temperature, turn off the engine. Now connect the red probe to the o2 sensor’s signal wire and the black probe to a good ground. Please use caution when connecting the probes as the engine and exhaust system will be extremely hot.
  4. To perform the actual test, start the car again and check the voltmeter’s voltage readings. The o2 sensor’s voltage should fluctuate within the 100mV – 900mV (0.10V to 0.90V) range. If it is within this range, the o2 sensor is operating normally and you can stop testing. In case it is not within range, there is either an engine problem (loose hose) or the o2 sensor is bad. If it appears to be bad, continue with the next steps.

is this the ground test you are referring too?
 
No, one of the wires from the O2 should attach to the engine as a ground. Usually a lean code means it's lean, not that the O2 has failed. Think of PO171/O2 lean as a symptom, not a diagnosis.
 
No, one of the wires from the O2 should attach to the engine as a ground.
sooooooo...... check the (probably black) ground wire at
1. where it connects to the sensor
2. both ends of the connecting harness
3. at the end where it connects to the ecu somehow?
do i need to find a wiring diagram to follow it all the way up to the ecu?
gonna go look at the pins and wires rt now.... its getting dark o00ooo00o0oo

***EDIT**
yeah there was a black wire coming out of the upstream o2 sensor which looks to be a couple years new.
the pins on the sensor end of the harness look fine

but i could not inspect the other end of the harness cuase it is way back and feels like it is held in place by something that feels like the litle plastic screw bit in the attatched picture.
can i just yank the harness off the holder without damaging it, or is there a technique for removal so i can inspect the wire harness that my o2 sensor plugs into.

also the threads on my o2 sensor seemed dry. it was easy to remove but felt dry upon re-installation. is this fine?

ALSO my obdii reader torque app reads something about
"Fuel System status
Closed loop, using O2 sensor for fuel mix
Secondary Air status
-
"
is this a clue as to my 'p0171: bank 1 running lean' issue?
 
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