I have a 95 Ford F350 with the 460 motor. It started running fine when cold but after it warms up it starts to run rough, lose power, and runs REAL rich. I'm only getting a little more than 2mpg.

"I would start by looking for a temperature sensor. You may have 2, with 1 being for the dash and the other being for the engine controls. You want to replace the temperature sensor for the Engine controls." I found 2 sensors on top of the intake and when I unplug either of them the check engine light comes on but the truck sounds the same and smells the same for either one I unplug. I cannot seem to find the one i need for the engine controls. Its a 460 7.5L "I would start by looking for a temperature sensor. You may have 2, with 1 being for the dash and the other being for the engine controls. You want to replace the temperature sensor for the Engine controls." I found 2 sensors on top of the intake and when I unplug either of them the check engine light comes on but the truck sounds the same and smells the same for either one I unplug. I cannot seem to find the one i need for the engine controls. Its a 460 7.5L

You have found both of them. If the dash gauge at any temperature above the cold mark drops to cold when the sensor is unplugged, then it is the dash gauge sensor. The other control snesor should send the temperature signal to the ECM. If you unplug the sensors and it generates a "check light" then a scanner should give a Code for that disconnected sensor. If you need a free scan, the Autoparts stores will do them. To help you find the right wires, Autozone.com offers free wiring and fusebox diagrams when you register on their site. Check your fuel pressure. Check your brakes for dragging. The strange thing about your problem is that by telling me a "CHECK LIGHT" is working, means your onboard computer must be working. Any problem severe enough to get you 2MPG should be generating more problem Codes. This would mean the problem is in an area that the Onboard computer does not monitor. That is why I mentioned Brakes. But if the engine is running that rich, the O2 sensors should be screaming about the problem and they are not. So even if the timing jumped, which probably would be missed by the onboard computer, the O2's should be signalling a rich mix. Try disconnecting the O2 harness to each sensor and see if the onboard computer notices. Then clear the computer and do the same with each sensor, letting it identify the individual O2 sensor by clearing the check light each time. The Dealers have a more powerful computer, I think it is called an Odessey which is installed for a ROAD TEST. It tells everything. You have found both of them. If the dash gauge at any temperature above the cold mark drops to cold when the sensor is unplugged, then it is the dash gauge sensor. The other control snesor should send the temperature signal to the ECM. If you unplug the sensors and it generates a "check light" then a scanner should give a Code for that disconnected sensor. If you need a free scan, the Autoparts stores will do them. To help you find the right wires, Autozone.com offers free wiring and fusebox diagrams when you register on their site. Check your fuel pressure. Check your brakes for dragging. The strange thing about your problem is that by telling me a "CHECK LIGHT" is working, means your onboard computer must be working. Any problem severe enough to get you 2MPG should be generating more problem Codes. This would mean the problem is in an area that the Onboard computer does not monitor. That is why I mentioned Brakes. But if the engine is running that rich, the O2 sensors should be screaming about the problem and they are not. So even if the timing jumped, which probably would be missed by the onboard computer, the O2's should be signalling a rich mix. Try disconnecting the O2 harness to each sensor and see if the onboard computer notices. Then clear the computer and do the same with each sensor, letting it identify the individual O2 sensor by clearing the check light each time. The Dealers have a more powerful computer, I think it is called an Odessey which is installed for a ROAD TEST. It tells everything.

I will try that in a while. I have noticed that the catallitic converter is rattling from the inside real bad so I guess I need to replace that also. The truck is on my last nerve right now so I am taking a few days off from it before I break other things with a hammer. lol I also noticed that when I rev it up alot it looks like fibers or something comming out the tail pipe, and it keeps blowing the Exhaust Manifold gasket in the same spot. I just put a new one in a little over a week ago and it blew it out again 4 days later. The parts stores will not check my truck because its a 95' OBD1. They only check OBD2 but I have a friend that has a scanner so I'm good there. I will try that in a while. I have noticed that the catallitic converter is rattling from the inside real bad so I guess I need to replace that also. The truck is on my last nerve right now so I am taking a few days off from it before I break other things with a hammer. lol I also noticed that when I rev it up alot it looks like fibers or something comming out the tail pipe, and it keeps blowing the Exhaust Manifold gasket in the same spot. I just put a new one in a little over a week ago and it blew it out again 4 days later. The parts stores will not check my truck because its a 95' OBD1. They only check OBD2 but I have a friend that has a scanner so I'm good there.

The Catalytic and the bad gasket are definitely signs of extreme Backpressure. But there is no explanation why the Onboard computer is not picking up a Distress call from the O2 sensors. Besides overheating problems in the exhaust, the O2 should notice the flow between the O2 sensors are uneven. Heat and flow are 2 things sensors should pick up. I can't remember now if the OBD1 can be read on the dash. The original systems on some Makes would blink a Code number on the dash "check" light if you jumped the connector terminals in a certain manner. Basically the switch on the OBD1 scanner does that job inside the machine when you switch on some of the butttons. But what you would still need to know what the Codes meant. The Catalytic and the bad gasket are definitely signs of extreme Backpressure. But there is no explanation why the Onboard computer is not picking up a Distress call from the O2 sensors. Besides overheating problems in the exhaust, the O2 should notice the flow between the O2 sensors are uneven. Heat and flow are 2 things sensors should pick up. I can't remember now if the OBD1 can be read on the dash. The original systems on some Makes would blink a Code number on the dash "check" light if you jumped the connector terminals in a certain manner. Basically the switch on the OBD1 scanner does that job inside the machine when you switch on some of the butttons. But what you would still need to know what the Codes meant.

There is only 1 oxygen sensor that I can find right under the assenger seat and that Autozone brings up. I unplugged it fron the harness, started the truck and let it run for a little bit. I even drove it around the block and the Check Engine light never turned on. I unplugged another sensor just to check the light and it came on so I guess my computer is screwed up or something. There is only 1 oxygen sensor that I can find right under the assenger seat and that Autozone brings up. I unplugged it fron the harness, started the truck and let it run for a little bit. I even drove it around the block and the Check Engine light never turned on. I unplugged another sensor just to check the light and it came on so I guess my computer is screwed up or something.

Also after I unplugged the sensor and drove it nothing changed. Still rich as hell and rough idle for about a minute then smothes out then goes back to rough. All vacuum lines are good, no leaks in fuel lines, front tankes pump is a lttle noisy but nothing changes when I switch to back tank. Also after I unplugged the sensor and drove it nothing changed. Still rich as hell and rough idle for about a minute then smothes out then goes back to rough. All vacuum lines are good, no leaks in fuel lines, front tankes pump is a lttle noisy but nothing changes when I switch to back tank.

The system should recognize that you have unplugged the O2 sensor. This would mean the computer is not even looking at the O2 when setting the engine parameters. Autozone.com will give wiring diagrams free when you register on their site as well as alldatadiy.com. This should enable you to follow the O2 wire back to the box where they connect. Check the connector plug, but I think a better scanner at a Dealer would test the PCM to see if it has a burned-out circuit. The basic handheld scanner varies from $70 to $5000 and some require updates at $1000 a crack, twice a year. Few Repair shops will spend that kind of money. You have little left to check. I may have mentioned extreme fuel pressure, clogged injectors, a stuck "cold start routine", but if you have proved the onboard computer does not know when the O2 sensor is disconnected, it kinda points to the PCM. But for the price and how long you have tried to fix this yourself, you may need to go beyond the PCM. Rather than hit or miss with expensive, nonreturnable, easily damaged parts, I would shop for a Repair place with superior diagnostics. After all, you can replace what they find and just get the diagnostics. But if it is more than 1 part, you may get a half way repair without letting them put in a PCM and continue testing. Also if you look at my second sentence in the original answer, I told you the O2 is not telling you a thing. You have found that out by unplugging it. Would like to know what was found to be the problem. The system should recognize that you have unplugged the O2 sensor. This would mean the computer is not even looking at the O2 when setting the engine parameters. Autozone.com will give wiring diagrams free when you register on their site as well as alldatadiy.com. This should enable you to follow the O2 wire back to the box where they connect. Check the connector plug, but I think a better scanner at a Dealer would test the PCM to see if it has a burned-out circuit. The basic handheld scanner varies from $70 to $5000 and some require updates at $1000 a crack, twice a year. Few Repair shops will spend that kind of money. You have little left to check. I may have mentioned extreme fuel pressure, clogged injectors, a stuck "cold start routine", but if you have proved the onboard computer does not know when the O2 sensor is disconnected, it kinda points to the PCM. But for the price and how long you have tried to fix this yourself, you may need to go beyond the PCM. Rather than hit or miss with expensive, nonreturnable, easily damaged parts, I would shop for a Repair place with superior diagnostics. After all, you can replace what they find and just get the diagnostics. But if it is more than 1 part, you may get a half way repair without letting them put in a PCM and continue testing. Also if you look at my second sentence in the original answer, I told you the O2 is not telling you a thing. You have found that out by unplugging it. Would like to know what was found to be the problem.

I appreciate all your help. I'm not good at these computer stuff on cars. That's why I like older vehicles better lol. I'm going to call the dealership tomorrow to see how much for their diagnostic test. After I get it done I will let you know what they found out. While I was under the truck undoing the O2 sensor, I unplugged a speed sensor to check the Check Engine light and it came on. Went off after I plugged the sensor back in so for some reason the O2 sensor is the only thing its not picking up. Like I said after I get the diagnostic done then I will let you know just incase you see someone with the same problem so you can tell them. While trying to fix this truck my 99 Nissan Frontier blew the dam Rear Main Seal. I'm gonna start drinking again lol. I appreciate all your help. I'm not good at these computer stuff on cars. That's why I like older vehicles better lol. I'm going to call the dealership tomorrow to see how much for their diagnostic test. After I get it done I will let you know what they found out. While I was under the truck undoing the O2 sensor, I unplugged a speed sensor to check the Check Engine light and it came on. Went off after I plugged the sensor back in so for some reason the O2 sensor is the only thing its not picking up. Like I said after I get the diagnostic done then I will let you know just incase you see someone with the same problem so you can tell them. While trying to fix this truck my 99 Nissan Frontier blew the dam Rear Main Seal. I'm gonna start drinking again lol.

When you go to the Dealer make sure they understand that you want the better test that Autozone,Oreilys. or Advance does for free. Tell them you have scanned the system with a handheld unit and are not paying for what you can get FREE at Autozone. You want the test that goes beyond the basic test because the other scanners have not picked up the problem. Since you are going there for the O2 problem, after Repair have them check the whole thing to insure you do better than 2MPG. As for Frontier, you may want to check Aboutautomobile.com and follow the Format to look up common problems and resolutions. For giggles you could check the F350 info too, but I doubt many people would get 2MPG and not be screaming for a Recall. When you go to the Dealer make sure they understand that you want the better test that Autozone,Oreilys. or Advance does for free. Tell them you have scanned the system with a handheld unit and are not paying for what you can get FREE at Autozone. You want the test that goes beyond the basic test because the other scanners have not picked up the problem. Since you are going there for the O2 problem, after Repair have them check the whole thing to insure you do better than 2MPG. As for Frontier, you may want to check Aboutautomobile.com and follow the Format to look up common problems and resolutions. For giggles you could check the F350 info too, but I doubt many people would get 2MPG and not be screaming for a Recall.