FuzzFace2 Posted December 22, 2017 Share Posted December 22, 2017 Thanks Gary! It is a mystery. I know far, far less than you about this stuff. It is my first go around.. An interesting point about the O2 sensor, I believe it is on the passenger side exhaust. The smoke issue is mainly on the drivers side. The suspect injector is on the driver side too. Doesn’t really help anything but it is an interesting observation.. I will keep muddling through, anything I note I will post here incase someone reads it and can help 😀 nor me an expert, but I did stay in a.....sorry My take on this, if the oil & coolant levels are staying the same, getting no codes, and as you pointed out the so called issue could be on the side with out the O2 it may not be picked up by the computer and show codes. I would put a can or 2 of Sea Foam thru it again then 2 or more tanks of straight fuel and then pull the plugs to see what they have to tell you. If all the plugs look good and everything else stays as it is I would just drive it. A little puff of oil smoke at start up I would call normal and condensate smoke till up to temp normal also. Now if motor is up to temp, gone down the road 5 to 10 miles and you stop and it smokes, unless it is cold out I would say it is not normal. But that is going by what I have seen in person and it is hard to say what this is over the internet like now. Dave ---- Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 22, 2017 Share Posted December 22, 2017 nor me an expert, but I did stay in a.....sorry My take on this, if the oil & coolant levels are staying the same, getting no codes, and as you pointed out the so called issue could be on the side with out the O2 it may not be picked up by the computer and show codes. I would put a can or 2 of Sea Foam thru it again then 2 or more tanks of straight fuel and then pull the plugs to see what they have to tell you. If all the plugs look good and everything else stays as it is I would just drive it. A little puff of oil smoke at start up I would call normal and condensate smoke till up to temp normal also. Now if motor is up to temp, gone down the road 5 to 10 miles and you stop and it smokes, unless it is cold out I would say it is not normal. But that is going by what I have seen in person and it is hard to say what this is over the internet like now. Dave ---- If the O2 sensor in on one leg and the problem is on the other then it wouldn't catch it. But, here's another thought - worn valve guides and seals. With the engine off oil will run down the valve stem and with bad seals/guides some will get through into the combustion chamber. So it'll smoke on startup. But, probably the only other time it may smoke is in high-vacuum situations, like coasting with the throttle closed. And, it won't use enough oil to be noticed. Link to comment Share on other sites More sharing options...
Gsmblue Posted January 17, 2018 Author Share Posted January 17, 2018 If the O2 sensor in on one leg and the problem is on the other then it wouldn't catch it. But, here's another thought - worn valve guides and seals. With the engine off oil will run down the valve stem and with bad seals/guides some will get through into the combustion chamber. So it'll smoke on startup. But, probably the only other time it may smoke is in high-vacuum situations, like coasting with the throttle closed. And, it won't use enough oil to be noticed. So the truck has been running ok, but I am still not happy with the smoke. I did not have much time today but I decided to try a couple of things. 1. pulled the cable off the #8 cylinder injector. - No difference in running at all. lumpy idle about 800-900rpm. 2. pulled the spark plug lead on #8 cylinder, injector unplugged. - lots of surging up and down between 1100 and 1300rpm. - very lumpy. So it is fair to say their could be a problem with the #8 injector? Link to comment Share on other sites More sharing options...
PetesPonies Posted January 17, 2018 Share Posted January 17, 2018 So the truck has been running ok, but I am still not happy with the smoke. I did not have much time today but I decided to try a couple of things. 1. pulled the cable off the #8 cylinder injector. - No difference in running at all. lumpy idle about 800-900rpm. 2. pulled the spark plug lead on #8 cylinder, injector unplugged. - lots of surging up and down between 1100 and 1300rpm. - very lumpy. So it is fair to say their could be a problem with the #8 injector? In both instances, you killed the #8 cylinder. Should be no difference. Link to comment Share on other sites More sharing options...
Gsmblue Posted January 17, 2018 Author Share Posted January 17, 2018 In both instances, you killed the #8 cylinder. Should be no difference. My thinking here is the injector is allowing gas into the cylinder no matter what. So the difference is when there is a spark the cylinder is kind of working, without spark the cylinder is dead. Does that make sense? I think the injector is allowimg gas through it no matter what the signal to the injector is. I will pull the spark plug and see how it looks too at some point.. Link to comment Share on other sites More sharing options...
NotEnoughTrucks Posted January 17, 2018 Share Posted January 17, 2018 My thinking here is the injector is allowing gas into the cylinder no matter what. So the difference is when there is a spark the cylinder is kind of working, without spark the cylinder is dead. Does that make sense? I think the injector is allowimg gas through it no matter what the signal to the injector is. I will pull the spark plug and see how it looks too at some point.. Keep in mind that these are batch fire injection. I don't know if killing an injector would positively kill the cylinder as there are other injectors firing and even if the affected cylinder would be leaned considerably, there may just be enough residual fuel fulled in with the charge that it would still appear to idle? Now, pulling the plug wire is another matter. You have proven that the cylinder is contributing. I think this will turn out to be valves and guides. How many miles are on this engine? How do the spark plugs look? Link to comment Share on other sites More sharing options...
Gsmblue Posted January 17, 2018 Author Share Posted January 17, 2018 Keep in mind that these are batch fire injection. I don't know if killing an injector would positively kill the cylinder as there are other injectors firing and even if the affected cylinder would be leaned considerably, there may just be enough residual fuel fulled in with the charge that it would still appear to idle? Now, pulling the plug wire is another matter. You have proven that the cylinder is contributing. I think this will turn out to be valves and guides. How many miles are on this engine? How do the spark plugs look? Interesting. I did not consider that. The engine has 118k miles on it... Link to comment Share on other sites More sharing options...
PetesPonies Posted January 18, 2018 Share Posted January 18, 2018 Interesting. I did not consider that. The engine has 118k miles on it... If you're talking about SPFI, then each injector is fired separately.And with the wire disconnected from the injector, it doesn't open. It works magnetically. No power, no electromagnet inside. No magnet, no opening. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 18, 2018 Share Posted January 18, 2018 If you're talking about SPFI, then each injector is fired separately.And with the wire disconnected from the injector, it doesn't open. It works magnetically. No power, no electromagnet inside. No magnet, no opening. Ray is correct - in speed density EFI systems, like used on the 1985 302, the injection was bank or batch-fired, meaning that injectors 1-4 were fired at the same time, and then 5-7 were fired. And, from what I can tell, 1-4 fired each time a cylinder on the passenger's side was ready to pull in fuel, and the same for the driver's side. (You can prove this by looking at the wire color to the injectors - there's only one color for each side.) So, there will be fuel in the intake manifold for each side that could make its way into another cylinder on that side even with one injector being disconnected. No, it wouldn't be nearly as much fuel as was needed to make that cylinder run properly. In fact, all four cylinders would be running on less fuel than they were supposed to have, although the ECU would try to compensate to some extent. But, since there's only one O2 sensor for the whole engine in the speed density system there's no way for the ECU to correctly compensate, and the engine will run poorly. Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 18, 2018 Share Posted January 18, 2018 Ray is correct - in speed density EFI systems, like used on the 1985 302, the injection was bank or batch-fired, meaning that injectors 1-4 were fired at the same time, and then 5-7 were fired. And, from what I can tell, 1-4 fired each time a cylinder on the passenger's side was ready to pull in fuel, and the same for the driver's side. (You can prove this by looking at the wire color to the injectors - there's only one color for each side.) So, there will be fuel in the intake manifold for each side that could make its way into another cylinder on that side even with one injector being disconnected. No, it wouldn't be nearly as much fuel as was needed to make that cylinder run properly. In fact, all four cylinders would be running on less fuel than they were supposed to have, although the ECU would try to compensate to some extent. But, since there's only one O2 sensor for the whole engine in the speed density system there's no way for the ECU to correctly compensate, and the engine will run poorly. Gary, all 8 cyl bank fired truck EFI systems are grouped 4 end and 4 center cyls. So Injector 1 circuit is 1,4,5,8, injector 2 circuit is 2,3,5,6. If he has a leaking #8 injector the O2 sensor on the 1985-86 302 will not detect it as it monitors 1-4 only (right side). That is why starting in 1987 Ford moved the sensor to beyond the Y in the exhaust. The 1985-86 O2 sensors are not heated so have to be close to the exhaust ports. Link to comment Share on other sites More sharing options...
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