bad idle
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bad idle
hi i got a 97 f150 4.2l from my neighbor. he takes good care of his vehicles. he sold it to me cuz it started to idle very rough like a misfire. it is hard to start when cold spits sputters and pops. once started idles like it wants to stall, then will idle normally then back to rough. back and forth like that. runs like a champ when going down the road . check engine light was on took it to auto store they checked codes . said bad o2 sensors so i changed them. still same issue. neighbor changed coil packs checked spark plugs and wire. every thing fires good. i changed iac. still didn't fix problem. could this be a bad egr valve or sensor? if so how can i diagnose this? he also thought was a clogged cat and bored it out. tight budget can't afford to take it to a mechanic. so any help or suggestions would be greatly appreciated.
was told spray carb cleaner spray around engine to check for leaks that did nothing at all...
was told spray carb cleaner spray around engine to check for leaks that did nothing at all...
Last edited by Allan Paulley Sr.; Jan 2, 2015 at 09:11 PM. Reason: adding more
Trailering
Joined: May 2011
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Apparently there is a common issue with the V6, as I am having the same problem. Put my scanner on it and got lean codes P0171 and P0174 on both banks. The problem (according to the place that did my emissions test) is a collapsed or leaking PCV fitting. I'm going to try fixing it tomorrow, if the dealer has the replacement part.
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You should have gotten the codes so we know what is going on.
Otherwise everybody you got advise from was wrong because they could not interpret the codes or just guessed..
My bet is an air leak in the intake system.
The system is hunting for a good idle it cannot attain due to the excess air..
Get the codes and post them
Good luck
Otherwise everybody you got advise from was wrong because they could not interpret the codes or just guessed..
My bet is an air leak in the intake system.
The system is hunting for a good idle it cannot attain due to the excess air..
Get the codes and post them
Good luck
Trailering
Joined: May 2011
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Just finished the fix. 
$15.00 part from the dealer problem solved. On the right rear (passenger) side of the upper intake there is an elbow that goes to the PCV located in the valve cover. Common problem with this model, this elbow collapses or just dry rots and breaks. You will need to disconnect the neg. batt. terminal and remove the two screws that secure the power distribution bracket to the firewall otherwise you will be working completely blind (you may need to disconnect two of the power supply cables attached to it). Once you remove this (actually you are just moving it down and out of your way, you do NOT have to remove it completely) you will be able to see the elbow coming off the manifold. There is a small diameter hose just in front and above it with a spring loaded clamp on it. This is a coolant line, disconnect this hose, (you won't lose more than a few ounces of coolant, just don't remove the coolant reservoir cap.) remove the old PCV elbow and replace it with the new one Ford #F65Z-6762-CA
Reconnect the coolant line and clamp, re-install the power distribution bracket and reconnect all the power connections and negative battery cable.
Problem should be solved, you may have to go in and clear the CEL if it is still on after you've finished.
$15.00 part from the dealer problem solved. On the right rear (passenger) side of the upper intake there is an elbow that goes to the PCV located in the valve cover. Common problem with this model, this elbow collapses or just dry rots and breaks. You will need to disconnect the neg. batt. terminal and remove the two screws that secure the power distribution bracket to the firewall otherwise you will be working completely blind (you may need to disconnect two of the power supply cables attached to it). Once you remove this (actually you are just moving it down and out of your way, you do NOT have to remove it completely) you will be able to see the elbow coming off the manifold. There is a small diameter hose just in front and above it with a spring loaded clamp on it. This is a coolant line, disconnect this hose, (you won't lose more than a few ounces of coolant, just don't remove the coolant reservoir cap.) remove the old PCV elbow and replace it with the new one Ford #F65Z-6762-CAReconnect the coolant line and clamp, re-install the power distribution bracket and reconnect all the power connections and negative battery cable.
Problem should be solved, you may have to go in and clear the CEL if it is still on after you've finished.
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bad idle
ok i changed the iac valve o2 sensors on both sides pre cat. i had to change starter so i disconnected battery. this was a few days ago. i went today to start it is very cold - temps. hesitated to start but started up and ran and idled fine. no check engine light. ran awhile . idled fine for the most part. drove home from garage i am using. check engine light came back. i got a scanner checked codes.
p0136
p0141
p0156
p0136
it also said 02 htr
egr
runs a slight bit off on idle but there is a exhaust leak just after the 02 sensor above the cat. could this be reason for it to be alittle off on idle now? nothing concerning, other then it doesn't idle as smooth as it should .
p0136
p0141
p0156
p0136
it also said 02 htr
egr
runs a slight bit off on idle but there is a exhaust leak just after the 02 sensor above the cat. could this be reason for it to be alittle off on idle now? nothing concerning, other then it doesn't idle as smooth as it should .
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Lead Driver
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Hi Allen,
....Your codes 136,141,156 indicate the Ox sensor heater circuits are in trouble.
....Are you sure you plugged them up solid all the way or there is harness/ connection issues? Check all 4 sensor plugs.
....The 1131, 1141 came is delayed because the computer sees both banks as lean. After a system power down these codes take time to show because the fuel tables have to shift out of limits to set these codes.
....I would correct the Ox sensor issues first, then see if the 1131/1141 codes are still showing after one or more drive cycles because the Ox sensors could report a false indication. You won't know this until they are repaired.
....Then if the 1131/1141 is still set you have an air leak in the intake system at some point leaning the A/F ratio to the point the Ox sensors are detecting such.
Good luck.
....Your codes 136,141,156 indicate the Ox sensor heater circuits are in trouble.
....Are you sure you plugged them up solid all the way or there is harness/ connection issues? Check all 4 sensor plugs.
....The 1131, 1141 came is delayed because the computer sees both banks as lean. After a system power down these codes take time to show because the fuel tables have to shift out of limits to set these codes.
....I would correct the Ox sensor issues first, then see if the 1131/1141 codes are still showing after one or more drive cycles because the Ox sensors could report a false indication. You won't know this until they are repaired.
....Then if the 1131/1141 is still set you have an air leak in the intake system at some point leaning the A/F ratio to the point the Ox sensors are detecting such.
Good luck.
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bad idle
they read bad in the first place so i changed the 2 by the manifold which i guessing is called the pre-cat ones. i find it highly doubtful that i changed them and put faulty or bad ones in. i did take the pcv out and inspected it and cleaned it up and put it back now i have those new codes. but seems to idle some what better then it did
Lead Driver
Joined: Sep 2006
Posts: 7,907
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Allen, I'm not sure were on the same page so to speak.
How did you come to 'read the front sensors bad'?
The 136/141 codes are for the heater circuits on the <rear> "rear" #2 Ox sensors.</rear>
You have to pay attention the code descriptions.
Are you seeing the differences?
You have to service for the codes first, then what is left over for drivability issues.
If you ignore this sequence you won't get repairs unless you have a lot of luck.
Good luck.
How did you come to 'read the front sensors bad'?
The 136/141 codes are for the heater circuits on the <rear> "rear" #2 Ox sensors.</rear>
You have to pay attention the code descriptions.
Are you seeing the differences?
You have to service for the codes first, then what is left over for drivability issues.
If you ignore this sequence you won't get repairs unless you have a lot of luck.
Good luck.
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bad idle
nope we weren't lmao. so my back 02 sensors are bad it is saying? ok will have to get those now i guess.
thank you for being patient i learning as we speaking about what and where these parts are.
thank you for being patient i learning as we speaking about what and where these parts are.
Lead Driver
Joined: Sep 2006
Posts: 7,907
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Allen, slow down a bit.
The codes are not necessarily telling you the sensors are faulty.
The codes 136/141 are for both banks.
I doubt they would both be faulty at the same time for the same fault.
Using a proper code description source, it tells you the sensor heater circuits are in fault. I repeat...sensor heater circuits.
Possibly your not understanding the sensors have two circuits each.
One is the heating element, the other is the Oxygen sensor detector.
This is why there are 4 leads to it, two for each function.
The heater function only is what the codes address for both sides.
Boiled down it's likely a harness issue of some sort.
Changing those sensors would not repair for the codes in that case.
You must pay attention to the specifics of the code descriptions so they don't miss-lead you by in attention to the detail in the descriptions..
Good luck.
The codes are not necessarily telling you the sensors are faulty.
The codes 136/141 are for both banks.
I doubt they would both be faulty at the same time for the same fault.
Using a proper code description source, it tells you the sensor heater circuits are in fault. I repeat...sensor heater circuits.
Possibly your not understanding the sensors have two circuits each.
One is the heating element, the other is the Oxygen sensor detector.
This is why there are 4 leads to it, two for each function.
The heater function only is what the codes address for both sides.
Boiled down it's likely a harness issue of some sort.
Changing those sensors would not repair for the codes in that case.
You must pay attention to the specifics of the code descriptions so they don't miss-lead you by in attention to the detail in the descriptions..
Good luck.
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bad idle
ok i am no mechanic by any means. don't know what or where any of the parts are on a vehicle for the most part. common stuff yes. so i am trying. i don't know what you mean about the tempature sensor/circuit. but i did have another egr valve and the sensor and pcv valve and boot. was going to change these things see if it fixes the issue. as i said i am no mechanic. so i open the hood looking at maf for some unknown reason. i see a big rubber boot looking thing on bottom of maf. it had 2 wires running throu it and rubber boot was not up into the maf where it was supposed to be, i put it back in. went to try to see if truck started and it fired right up been running good since. this was yesterday. now my tempature gauge sensor on engine is bad doesn't work. didn't work for a while. before i bought the truck from neighbor. i still smell a funny gas smell in my exhaust. please speak in dumb terms so i understand what it is your saying. lol as i said i am no mechanic and not rich to be able to take cars to garages .