Welcome Visitor! Please take a few seconds and - Joined
- Aug 15, 2007
- Messages
- 1,613
- Reaction score
- 46
- Points
- 48
- Location
- toenails of foothills NW of Atlanta
- Vehicle Year
- 1985
- Make / Model
- ford
- Engine Type
- 2.3 (4 Cylinder)
- Engine Size
- lima bean
- Transmission
- Manual
- 2WD / 4WD
- 2WD
- My credo
- vertical and above ground
Since O2 sensors seem to be the thought for the day, how about using a VOM to measure the signal coming out of the O2 heading to the computer? I understand it should flicker back and forth between .1v and ~.9v, more or less. It will not work until it is hot enough, and the computer will work in 'open loop' until then. Once heated, it goes into 'closed loop' where the feedback from the O2 is used to help tune the engine injection parameters.
Does the engine seem to have the same power that it had previously? Any sort of hesitation or other performance issue?
Since your truck is a 1997, it should have OBD-II, and a reader/scanner should be able to tell you what is going on temp/fuel/spark, etc. I would hook up to a scanner and look at the long & short term fuel trims, the 'reported' coolant temperature, and so on.
If you think about this, the engine itself, valves, cylinders, etc, are the same as 'yesterday', so it is a fuel/timing/ignition condition that is different. The things changed are the plugs/wires/thermostat, water pump, and timing belt, more or less. The things that can make the most difference are the plugs & wires, and the stat. Plugs & wires would cause misfire, the stat low or slow warmup. If the 'rubber' gasket on the stat did not seal to the inside of the housing, you'll get leakage past the stat, slower warmup, and perhaps lower operating temperature.
I have removed the throttle body on mine, to change the cam cover gasket, and when putting it back together, used the old gasket. I can 'feel' the TB fit into the depressions on the gasket, and hold it there while tightening the weird nuts. If you have an air leak on one of the intake gaskets, you'd be getting a 'lean' condition from the O2's, yet the MAF would report only X.x liters of air coming in... Misfire in one cylinder can feed the O2's again a 'lean' condition, because there are O2 molecules that have not been consumed by combustion, so the computer will again add fuel to ALL cylinders to try to get rid of the 'lean'. EGR ports in the 3.8 are in the bottom of the intake, directly opposite the intake valves. They can clog, and then all the EGR gas is fed to the most open port... and causes misfire due to the gas, leading to excess O2's in the exhaust ... again telling the computer HEY!!! richen it up, I have extra O2s coming by, I can burn more fuel.... and produce a cleaner exhaust... So, one problem can lead to another completely off track, so to speak.
Pull the plugs and see if they look good. Nice, clean, slightly tan in color, with no oil or carbon 'fluff' deposits. If they differ, from that or one to the others, it may be an indicator of what's going on.
Some plug wires need to have the metal conductor closed up a bit to make good, continuous contact with the plug terminal. You do that by squeezing the boot, or by pushing the wire further onto the boot so the connector is exposed. (I prefer just the squeeze as plug wire is sort of delicate, being just fiber mixed with a carbon conductor)
If you have a high speed misfire, you may not be able to detect it without instruments.
tom
Does the engine seem to have the same power that it had previously? Any sort of hesitation or other performance issue?
Since your truck is a 1997, it should have OBD-II, and a reader/scanner should be able to tell you what is going on temp/fuel/spark, etc. I would hook up to a scanner and look at the long & short term fuel trims, the 'reported' coolant temperature, and so on.
If you think about this, the engine itself, valves, cylinders, etc, are the same as 'yesterday', so it is a fuel/timing/ignition condition that is different. The things changed are the plugs/wires/thermostat, water pump, and timing belt, more or less. The things that can make the most difference are the plugs & wires, and the stat. Plugs & wires would cause misfire, the stat low or slow warmup. If the 'rubber' gasket on the stat did not seal to the inside of the housing, you'll get leakage past the stat, slower warmup, and perhaps lower operating temperature.
I have removed the throttle body on mine, to change the cam cover gasket, and when putting it back together, used the old gasket. I can 'feel' the TB fit into the depressions on the gasket, and hold it there while tightening the weird nuts. If you have an air leak on one of the intake gaskets, you'd be getting a 'lean' condition from the O2's, yet the MAF would report only X.x liters of air coming in... Misfire in one cylinder can feed the O2's again a 'lean' condition, because there are O2 molecules that have not been consumed by combustion, so the computer will again add fuel to ALL cylinders to try to get rid of the 'lean'. EGR ports in the 3.8 are in the bottom of the intake, directly opposite the intake valves. They can clog, and then all the EGR gas is fed to the most open port... and causes misfire due to the gas, leading to excess O2's in the exhaust ... again telling the computer HEY!!! richen it up, I have extra O2s coming by, I can burn more fuel.... and produce a cleaner exhaust... So, one problem can lead to another completely off track, so to speak.
Pull the plugs and see if they look good. Nice, clean, slightly tan in color, with no oil or carbon 'fluff' deposits. If they differ, from that or one to the others, it may be an indicator of what's going on.
Some plug wires need to have the metal conductor closed up a bit to make good, continuous contact with the plug terminal. You do that by squeezing the boot, or by pushing the wire further onto the boot so the connector is exposed. (I prefer just the squeeze as plug wire is sort of delicate, being just fiber mixed with a carbon conductor)
If you have a high speed misfire, you may not be able to detect it without instruments.
tom
