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Car Forum / Ford / Ford Trucks / October 20061995 F150 Help - Can not fix!
I have a 1995 F150 4X4 with a 5.0 Automatic. It runs fine sometimes but then it will bog under part throttle, pop back and run crappy until wide open throttle then it takes off and runs great. Always runs great at wide open throttle. Occasionally it will stumble at an idle but most of the time it idles perfect. It gives a lean code but as it is obd 1(stupid as I call it) no data stream. Here is what I have done so far. A lot of this is as it is my sons first truck and I just want it all ready as soon as he gets his license in the next month. New plugs, wires, cap, rotor & distributor Changed computer - same exact symptoms as the original one Fuel pressure test while driving on two tanks all is fine New mass air New fuel filter New throttle position sensor Cat is punched out O2 sensor was replaced before I got it Cleaned all grounds It doesn't skip or run bad on any cylinder but just like something is not telling the injectors to open all of the way until you hit wide open throttle then it goes great. It is worse up a hill but will do it on the flat also. The check engine light will cycle on and off but only shows the lean bank 1 code. I am hoping the different computer may come up with a new code. Thanks in advance for all of your suggestions!  SignatureWhy just do a job when you can OVERKILL it! >I have a 1995 F150 4X4 with a 5.0 Automatic. It runs fine sometimes but >then it will bog under part throttle, pop back and run crappy until wide [quoted text clipped - 23 lines] > > Thanks in advance for all of your suggestions! Sounds like the timing is way off. Spdloader The timing has been set at 10 BTDC when the new distributor was installed. SignatureWhy just do a job when you can OVERKILL it! > >>I have a 1995 F150 4X4 with a 5.0 Automatic. It runs fine sometimes but [quoted text clipped - 27 lines] > Sounds like the timing is way off. > Spdloader > The timing has been set at 10 BTDC when the new distributor was installed. > [quoted text clipped - 28 lines] >> Sounds like the timing is way off. >> Spdloader > The timing has been set at 10 BTDC when the new distributor was installed. Even so, the new distributor may not be working properly. Also, was the timing set with the pigtail to the distributor unplugged? Then, plugged back in? Spdloader Yes the pitail was removed and reinstalled after timing. SignatureWhy just do a job when you can OVERKILL it! > >> The timing has been set at 10 BTDC when the new distributor was [quoted text clipped - 39 lines] > > Spdloader > I have a 1995 F150 4X4 with a 5.0 Automatic. It runs fine sometimes but then > it will bog under part throttle, pop back and run crappy until wide open [quoted text clipped - 4 lines] > my sons first truck and I just want it all ready as soon as he gets his > license in the next month. Lean is lean. I'd be careful if it is truly having trouble with a cylinder as you could fry an exhaust valve or a piston if the cylinder isn't getting enough fuel. Have you got a code scanner? Have you run the cylinder balance test to check for a weak cylinder? Beyond that, understand that at WOT, the engine computer goes into open loop mode where it basically ignores the oxygen sensor input and just uses some tables it stores and just pushes fuel out the injectors like crazy. Try wot in a building and you'll smell the unburned fuel. So if this is at part throttle, it would lead me to think perhaps an issue related to computer control. I would recommend making sure that the cooling system is functioning properly and that the sensors that check coolant temperature are working. This is an input to the computer. I'd try running with the MAF sensor disconnected to see how it does and if the behavior changes any. Without the maf sensor you'll get a check engine code but the computer will use defaults and should run o.k. After that you have to consider a possible issue like a bad distributor or worn distributor allowing too much movement. tp s >I have a 1995 F150 4X4 with a 5.0 Automatic. It runs fine sometimes but >then it will bog under part throttle, pop back and run crappy until wide [quoted text clipped - 23 lines] > > Thanks in advance for all of your suggestions! I have already replaced the tps and no change. SignatureWhy just do a job when you can OVERKILL it! > tp > [quoted text clipped - 27 lines] >> >> Thanks in advance for all of your suggestions! "LOOK2X" wrote: 1995 F150 4X4 5.0 Automatic. Runs fine then will bog under part throttle, pop back and run crappy, always runs great with WOT. Occasional stumble at an idle but most of the time idles perfect. Gives a lean code (OBD-I). Here is what I have done: New plugs, wires, cap, rotor & distributor Changed computer - same exact symptoms as the original one Fuel pressure test while driving on two tanks all is fine New mass air New fuel filter New throttle position sensor Cat is punched out O2 sensor was replaced before I got it Cleaned all grounds _______________________________________________ Possibly loose bolts holding throttle body, or sticking IAC. Good luck. Rodan. > "LOOK2X" wrote: 1995 F150 4X4 5.0 Automatic. > > Cat is punched out Punched out cat can affect exhaust temp, which is what an O2 sensor measures. Its nothing more than thermocouple like on a hot water heater. If the exhaust is to cool its voltage out put will be low which tells the ecm its running rich, so the ecm leans out the fuel mix, which raises combustion temps which can cause back fires. WOT, the O2 is ignored. How many O2's on this model? Whitelightning >> "LOOK2X" wrote: 1995 F150 4X4 5.0 Automatic. >> [quoted text clipped - 3 lines] > O2 sensor measures. Its nothing more than thermocouple > like on a hot water heater. That is not correct. The O2 sensor measures the presense of oxygen via an electrochemical reaction on a ceramic element. It is not a thermocouple. http://patft.uspto.gov/netahtml/PTO/srchnum.htm Patent # 3933028 SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 24 days 10:17 > That is not correct. The O2 sensor measures the presense of oxygen > via an electrochemical reaction on a ceramic element. It is not > a thermocouple. > > http://patft.uspto.gov/netahtml/PTO/srchnum.htm > Patent # 3933028 How do you bench test a O2 sensor? Whitelightning >> That is not correct. The O2 sensor measures the presense of oxygen >> via an electrochemical reaction on a ceramic element. It is not [quoted text clipped - 6 lines] > > Whitelightning I haven't tried this, but the theory says that since the chemical reaction doesn't occur unless it's hot, you would have to heat it with a propane torch, or something like that. When it was in the flame, it should indicate rich, or centered (since the propane was consuming the oxygen) and out of the flame, it should indicate lean (lower voltage) until it cools off, then it would read nothing. YMMV SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 24 days 18:28 >>> That is not correct. The O2 sensor measures the presense of oxygen >>> via an electrochemical reaction on a ceramic element. It is not >>> a thermocouple. >>> >>> http://patft.uspto.gov/netahtml/PTO/srchnum.htm >>> Patent # 3933028 PS, you left out your statement from earlier: On Sun, 22 Oct 2006 02:08:36 +0000, Whitelightning rearranged some electrons to form: Punched out cat can affect exhaust temp, which is what an O2 sensor measures. Its nothing more than thermocouple like on a hot water heater. >> How do you bench test a O2 sensor? >> [quoted text clipped - 8 lines] > > YMMV SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 24 days 18:44 > >> How do you bench test a O2 sensor? > >> [quoted text clipped - 6 lines] > > and out of the flame, it should indicate lean (lower voltage) until it > > cools off, then it would read nothing. You can do the same thing with an electric heat gun, such as a paint stripper, which has no flame. Whitelightning >> >> How do you bench test a O2 sensor? >> >> [quoted text clipped - 13 lines] > > Whitelightning Perhaps, but you're original statement is still wrong. >On Sun, 22 Oct 2006 02:08:36 +0000, Whitelightning rearranged some >electrons to form: > > Punched out cat can affect exhaust temp, which is what an > O2 sensor measures. Its nothing more than thermocouple > like on a hot water heater. An O2 sensor is *not* a temperature sensor. It measures the partial pressure of oxygen. It requires heat for the chemical reaction to occur between the oxygen and the ceramic element. At a given temperature, it will output a different voltage based on the oxygen content of the gas around it. If you heated it with a heat gun, the voltage will drop as the sensor cools off, as the chemical reaction stops... thus the reason that most O2 sensors have a built-in heater so they will come up to temperature quickly. Don't believe me? Read it yourself: http://auto.howstuffworks.com/question257.htm A thermocouple is a junction of dissimlar metals, which generates a very small voltage (millivolts) based on temperature based on the Seebeck effect. The presence or absence of oxygen has no effect on a thermocouple. http://en.wikipedia.org/wiki/Thermocouple There are many more references out there, if you'll take the time to search. SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 25 days 17:04 >>> >> How do you bench test a O2 sensor? >>> >> [quoted text clipped - 44 lines] > There are many more references out there, if you'll take the time to > search. Here's some more: http://www.omega.com/thermocouples.html http://www.boschautoparts.com/FAQs/default.htm (select oxygen sensors) SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 25 days 17:29 I concede the point that they are 'different" devices. I can learn and admit when I am wrong. However, if the temperature isn't correct it is going to read wrong. What is hard to understand here is the bank one lean error code. If there is only one O2 sensor, how can the system determine a lean bank? Whitelightning > What is hard to understand here is the bank one lean error code. > If there is only one O2 sensor, how can the system determine > a lean bank? > > Whitelightning Some of those trucks had two O2 sensors, one in each downpipe, (one from each bank(head)) just before they entered the converter. Maybe that's how. Spdloader > I concede the point that they are 'different" devices. I can learn > and admit when I am wrong. > However, if the temperature isn't correct it is going to read wrong. Correct, that's why they have a built-in heater to get them up to temperature quickly. Older ones didn't have the heater and thus ran open-loop until the engine warmed up, spewing a lot of unburned fuel. I can't remember the exact number, but a model from this decade (2000's) has something like 100 times cleaner emissions than something from 20 years ago. > What is hard to understand here is the bank one lean error code. If > there is only one O2 sensor, how can the system determine a lean bank? > > Whitelightning It probably has more than one sensor. My OBD-II '98 has four. I haven't had to change them (yet) after 123k on the clock. I've replaced the one on the wife's '94 Jeep twice in the past 12 years, though. Go figure. SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 26 days 16:55 It only has one o2 sensor. Lean bank1 is the default language for lean exhaust which is all it knows with only one o2 sensor. The truck is now fixed. With the computer replaced we were able to get a data stream, and from that we could see that the new o2 sensor was bad and only going from full rich to full lean. Replaced the o2 sensor and all is well again. Thanks for all of your input! SignatureWhy just do a job when you can OVERKILL it! > >> I concede the point that they are 'different" devices. I can learn [quoted text clipped - 17 lines] > I've replaced the one on the wife's '94 Jeep twice in the past 12 years, > though. Go figure. ... > It probably has more than one sensor. My OBD-II '98 has four. > I haven't had to change them (yet) after 123k on the clock. > I've replaced the one on the wife's '94 Jeep twice in the past 12 years, > though. Go figure. OBB I - 1 sensor per converter per bank. So two banks, but one converter, one oxy sensor. Two banks and two converters, two oxy sensors. OBD II - 2 sensors per converter per bank. Oxy sensors check exhaust ahead of the converter and then after the converter. Thus the efficiency of the converter can be validated and if a problem is detected a check engine light is lit. did you pull the timing advanceplug before timing? loose timing chain? http://www.minibite.com/america/malone.htm |
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