lelandEOD
SILVER Star
Fellow 3FE compatriots,
I’m running into a stubborn problem with a freshly rebuilt 3FE I’ve installed in a '73 FJ40 and want this thread to serve as a case study on the diagnostic tests illustrated in the Toyota 3FE Engine Supplement.
Brief backstory-
The engine I’m working on is the second 3FE I’ve had for this truck. The first was just a runner I picked up at a swapmeet. Since it made good compression, I made the decision to clean up and run it while I sourced a second 3FE that would go under the knife for a proper rebuild. I ran that first engine for almost two years and had constant problems with occasional pinging, suspected lean-running, smelly exhaust, etc. In September 2016, it blew a head gasket as I literally coasted into my driveway. I had pulled my hair out up to that point, trying in vain to figure out what was going on. The exhaust smell always made me think it was running fat, but a spark plug inspection always yielded white looking plugs. I went through several sets of O2 sensors too as I thought it was a sensor-related problem for the longest time. I also changed my fuel delivery system to better supply fuel under load, but nothing solved the smelly exhaust and the dead spot in the mid-rpm band.
After the head gasket popped, I convinced myself the problem was due to excessive oil consumption - it did burn a quart or so between changes and the engine had over 260k on it. My thought was that if the valve guides and/or seals were toast the motor was sucking too much oil into the combustion chamber. I theorized this excess oil was flooding the exhaust with excess hydrocarbons and confusing and/or damaging the O2 sensors. I further theorized that this explained the white spark plugs as the ECU might be trying to compensate by leaning out the mixture – exacerbating the problem and killing the head gasket. (Spoiler Alert: I don’t think this was the case)
Why you ask? Because I now have a completely rebuilt and reconditioned 3FE sitting in the truck and things are not well. I used all new Toyota parts (ever try sourcing NOS "T" marked bearings for a 3FE? - loads of fun). Literally, a full-retard rebuild: all rotating parts magnafluxed, polished, and balanced. Toyota bearings, Toyota rings, Toyota oil pump, Toyota cam gears… The head received new Toyota valves, new seats, guides, and springs by a very reputable ‘cruiser shop. Also, since I had gone through so much frustration troubleshooting the old engine issues, I also installed a fuel pressure sender on the fuel rail and a wideband O2 sensor/controller (downstream from the factory sensors) to make future troubleshooting efforts easier.
Last week, I topped off the oil, double-checked my connections, solved a ground-fault in the AFM circuit and fired it up - only to discover that it is running EXACTLY like the old engine <Heartbreaking>. It has the same very slight sputter in the exhaust at idle; the exhaust fumes are pungent and very noxious hot or cold and I can hear a slight miss when warm (at idle as well as when it revs). Following the instructions in the FSM, I’ve re-adjusted the valves on a warm engine and set the timing according to the specified procedure.
The engine starts easily. I think I can hear it go from closed loop to reading off the O2s as it warms up and the idle drops. That’s when I can really start to hear the miss in the exhaust pipe. I’ve only driven it up and down the highway a couple times. As I accelerate, I can feel what I would describe as a slight dead spot in the 1,800-2,500 rpm range. Fuel pressure at idle is steady at 34 psi at idle and increases to about 40 psi while accelerating. Also, the Innovative wideband O2 sensor is averaging 15.5:1 air/fuel at warm idle so it is running slightly lean. DANG! The A/F ratio fluctuates while under acceleration but I can say it appears to be rich (~10:1 under acceleration) and goes full lean when I let off (~22:1) before returning to about 15.5-16:1. Double DANG.
This brings us up to now. I’ve decided I need to go back to basics, start from scratch, and begin troubleshooting all over.
Let the Battle of Wits Begin.
I’m running into a stubborn problem with a freshly rebuilt 3FE I’ve installed in a '73 FJ40 and want this thread to serve as a case study on the diagnostic tests illustrated in the Toyota 3FE Engine Supplement.
Brief backstory-
The engine I’m working on is the second 3FE I’ve had for this truck. The first was just a runner I picked up at a swapmeet. Since it made good compression, I made the decision to clean up and run it while I sourced a second 3FE that would go under the knife for a proper rebuild. I ran that first engine for almost two years and had constant problems with occasional pinging, suspected lean-running, smelly exhaust, etc. In September 2016, it blew a head gasket as I literally coasted into my driveway. I had pulled my hair out up to that point, trying in vain to figure out what was going on. The exhaust smell always made me think it was running fat, but a spark plug inspection always yielded white looking plugs. I went through several sets of O2 sensors too as I thought it was a sensor-related problem for the longest time. I also changed my fuel delivery system to better supply fuel under load, but nothing solved the smelly exhaust and the dead spot in the mid-rpm band.
After the head gasket popped, I convinced myself the problem was due to excessive oil consumption - it did burn a quart or so between changes and the engine had over 260k on it. My thought was that if the valve guides and/or seals were toast the motor was sucking too much oil into the combustion chamber. I theorized this excess oil was flooding the exhaust with excess hydrocarbons and confusing and/or damaging the O2 sensors. I further theorized that this explained the white spark plugs as the ECU might be trying to compensate by leaning out the mixture – exacerbating the problem and killing the head gasket. (Spoiler Alert: I don’t think this was the case)
Why you ask? Because I now have a completely rebuilt and reconditioned 3FE sitting in the truck and things are not well. I used all new Toyota parts (ever try sourcing NOS "T" marked bearings for a 3FE? - loads of fun). Literally, a full-retard rebuild: all rotating parts magnafluxed, polished, and balanced. Toyota bearings, Toyota rings, Toyota oil pump, Toyota cam gears… The head received new Toyota valves, new seats, guides, and springs by a very reputable ‘cruiser shop. Also, since I had gone through so much frustration troubleshooting the old engine issues, I also installed a fuel pressure sender on the fuel rail and a wideband O2 sensor/controller (downstream from the factory sensors) to make future troubleshooting efforts easier.
Last week, I topped off the oil, double-checked my connections, solved a ground-fault in the AFM circuit and fired it up - only to discover that it is running EXACTLY like the old engine <Heartbreaking>. It has the same very slight sputter in the exhaust at idle; the exhaust fumes are pungent and very noxious hot or cold and I can hear a slight miss when warm (at idle as well as when it revs). Following the instructions in the FSM, I’ve re-adjusted the valves on a warm engine and set the timing according to the specified procedure.
The engine starts easily. I think I can hear it go from closed loop to reading off the O2s as it warms up and the idle drops. That’s when I can really start to hear the miss in the exhaust pipe. I’ve only driven it up and down the highway a couple times. As I accelerate, I can feel what I would describe as a slight dead spot in the 1,800-2,500 rpm range. Fuel pressure at idle is steady at 34 psi at idle and increases to about 40 psi while accelerating. Also, the Innovative wideband O2 sensor is averaging 15.5:1 air/fuel at warm idle so it is running slightly lean. DANG! The A/F ratio fluctuates while under acceleration but I can say it appears to be rich (~10:1 under acceleration) and goes full lean when I let off (~22:1) before returning to about 15.5-16:1. Double DANG.
This brings us up to now. I’ve decided I need to go back to basics, start from scratch, and begin troubleshooting all over.
Let the Battle of Wits Begin.
