2.9 Runs bad when warm
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2.9 Runs bad when warm
So here it is...
88 ranger 2.9L about 120k miles
pulled the codes with a test light and,
KOEO - 41
Memory - 41
KOER - 11
I've been looking through the other threads for a similar problem
but havent found the same, they are all a bit different...
Any sugesstions would be greatly appreciated...
Oh yes, cap, rotor, wires, plugs are all brand new...
Thanks
88 ranger 2.9L about 120k miles
pulled the codes with a test light and,
KOEO - 41
Memory - 41
KOER - 11
I've been looking through the other threads for a similar problem
but havent found the same, they are all a bit different...
Any sugesstions would be greatly appreciated...
Oh yes, cap, rotor, wires, plugs are all brand new...
Thanks
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
A 41 can't be a KOEO code; the engine can't test the O2 sensor when the engine isn't running.
That said, it appears you have an intermittent O2 sensor fault (the code shows up in CM, but not during the KOER test). 1st step would be to check the wiring between the O2 sensor and the computer to make sure there are no loose connections. From there you need to check fuel pressure, O2 sensor output, MAP signal and a whole host of other things. Be sure to recognize that we are dealing with a somewhat intermittent fault, so you'll need to adjust your diagnosis accordingly.
That said, it appears you have an intermittent O2 sensor fault (the code shows up in CM, but not during the KOER test). 1st step would be to check the wiring between the O2 sensor and the computer to make sure there are no loose connections. From there you need to check fuel pressure, O2 sensor output, MAP signal and a whole host of other things. Be sure to recognize that we are dealing with a somewhat intermittent fault, so you'll need to adjust your diagnosis accordingly.
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Well it's been a while since i've gotten a chance to look a the ranger...
but today I checked the wiring to the O2 senser, looked good, checked the
fuel pressure, looked good, but when i did a voltage test on the
MAP sensor, it read a constant ~2.25 volts... unless i am mistaken,
it should read 3.5-4.5 KOEO, and 1.5-2.5 when it's at a warm idle...
also when i touch the MAP out lead to the block, the engine acts similar
to when i am driving it... could a bad MAP sensor be it possibly???
but today I checked the wiring to the O2 senser, looked good, checked the
fuel pressure, looked good, but when i did a voltage test on the
MAP sensor, it read a constant ~2.25 volts... unless i am mistaken,
it should read 3.5-4.5 KOEO, and 1.5-2.5 when it's at a warm idle...
also when i touch the MAP out lead to the block, the engine acts similar
to when i am driving it... could a bad MAP sensor be it possibly???
Postmaster
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From: UT
A bad MAP sensor could cause an O2 sensor code. However, unless you have the special MAP tester, voltage isn't the proper way to test a Ford MAP sensor. Your MAP sensor's output is actually frequency. Ford's MAP tester converts the frequency to a voltage that you can measure, or you can measure the MAP output directly if you have a multimeter with a good frequency function. My MAP sensor output is .11 (high vacuum) to 0.16 (ambient pressure. note that I'm about 5000 ft above sea level) kHz.
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It seems like years between my posts...
I started in on my truck again, taking into consideration the last post
(thanks mrshorty)...
the Map sensor has open loop ~.162 kHz
closed loop(hot engine) ~ .105 kHz
the fuel pressure at the rail is about 33 psi, and it does vary a bit when the
engine is dying out... the only thing i can think now is the O2 sensor, or
possibly the injectors are so clogged with junk they aren't operating
correctly... if you have any ideas please let me know...
I started in on my truck again, taking into consideration the last post
(thanks mrshorty)...
the Map sensor has open loop ~.162 kHz
closed loop(hot engine) ~ .105 kHz
the fuel pressure at the rail is about 33 psi, and it does vary a bit when the
engine is dying out... the only thing i can think now is the O2 sensor, or
possibly the injectors are so clogged with junk they aren't operating
correctly... if you have any ideas please let me know...
Postmaster
Joined: Dec 2001
Posts: 3,742
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From: UT
In what way does the fuel pressure vary as the engine dies out? How much does it vary? With the vacuum line connected to the FPR, it will vary some, because engine vacuum effects the pressure the FPR sets, and the engine vacuum will fluctuate as the engine stumbles. You might try the same thing, only this time unhook the vacuum line to the FPR and plug the line, so the FPR isn't effected.
Another thought. Have you ever cleared the CM codes and see if the 41 comes back consistently? That might be an interesting little test.
Have you put your voltmeter on the O2 signal wire to see what the O2 sensor is outputting?
Another thought. Have you ever cleared the CM codes and see if the 41 comes back consistently? That might be an interesting little test.
Have you put your voltmeter on the O2 signal wire to see what the O2 sensor is outputting?
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I will try plugging the line going into the FPR today along with the
output voltage from the o2 sensor... one question, i read somewhere that
the o2 sensor has an isolated ground, so would this mean that i could
not ground to the block for testing the lead? or is grounding to the
block an acceptable ground spot...
output voltage from the o2 sensor... one question, i read somewhere that
the o2 sensor has an isolated ground, so would this mean that i could
not ground to the block for testing the lead? or is grounding to the
block an acceptable ground spot...
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89 ford ranger xlt
Im having the exact same problem with my ranger.I get a code 41 when it warms up. I replaced many parts and sensors but have not found the problem . Hope somebody out there knows what is causing it.
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From: UT
29leroylane: Can you be more specific about what you've done? A lean O2 sensor code can be one of the more difficult codes to diagnose, and you've given next to no information. Is it a KOER or CM 41 or both? Have you checked the fuel pressure? The wires leading to the O2 sensor? Computer grounds?
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So far I have replaced the fuel pump, fuel filter, fuel regulator, oxygen sensor,throttle position sensor,checked ground for ecm, checked wiring for oxygen sensor, checked manifolds for cracks.After driving for awhile the check engine light comes on & exhaust has black soot on tailpipe.Truck does not have alot of power on the highway. Compression test showed all cylinders around 190 psi. KOEO test shows code 41. What should I do next to determine the cause of the problem?Thanks
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From: UT
You've done a lot of replacing. What is your fuel pressure (with all the new parts)? Can you backprobe the O2 sensor circuit and see what the sensor output is doing? Is your MAP output reasonable (note that you need a frequency counter or special MAP tester to test)? Is it misfiring?
At this point, you've already thrown a lot of money in parts at it. If you get in above your skill level, it might be worth the ~$60 diagnostic fee to have a shop look at it.
At this point, you've already thrown a lot of money in parts at it. If you get in above your skill level, it might be worth the ~$60 diagnostic fee to have a shop look at it.
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I have had the truck diagnosed with the code 41 at a mechanic shop. They replaced the fuel pump, filter and regulator.I still had the same problem afterwards. Seems most shops like to throw parts at the problem anyway .I picked up the rest of the parts I replaced myself very cheap.Can a good Mechanic pinpoint the exact problem without replacing alot of parts?
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