89 xj 4.0 renix manual
southern california, mid december 2011
about 190,000 miles
failed smog in every category except 25 mph NOX
besides failing smog, engine was hard to start hot and always smelled a little too gassy. never felt very peppy.
tested inlet and outlet temps of catalytic converter. outlet was significantly higher than inlet (indicating it works to some extent)
compression on all cylinders is 140 to 150 psi.
spark plugs look great with no fouling and they must have about 20k miles on them.
passed smog 2 years ago.
connected DRB II and ran engine test. returned with fault 1065 , which is O2 sensor running rich. the troubleshooting chart for that fault involves disconnecting the o2 sensor, and then monitoring the o2 sensor voltage while shorting various terminals on the harness. im not sure if i was doing this wrong, but my drb ii never showed anything but 0V (shorted or not) during this test, even when the actual pins on the harness measured 5V (not shorted).
i measured the voltage for the heater of the o2 sensor, and found it was 0V. This is because its only 12-14V for about A SECOND after you turn the key on. once i discovered this, i found the voltage to be about 12V for the o2 heater.
while running, the O2 sensor voltage (monitored via DRB 2) clearly swang between 1 and 4V like it should. it appeared to be working.
so now I began to believe the fault 1065 was real, and there was something causing the system to run rich at some point during the engine test, and the O2 sensor was probably working ok.
measured fuel rail pressure. 33psi at idle with vac hose, 40psi idle without vac hose. if engine is shut off, loses pressure at about 1 psi every 7 seconds.
removed fuel rail to observe injectors for leaking. noticed that tons of fuel would leak if i moved injectors around. it was leaking past the fuel rail orings. the intake manifold orings looked okay, but the fuel rail orings were hard as rocks. replaced all. now the leak was fixed, so i could actually observe the injectors outputs for leaks. none seen. suddenly i noticed that there was fuel dribbling out of the fuel pressure regulator vacuum line nipple.
so I'm assuming that was the whole problem. the intake manifold was sucking gobs of fuel through the fuel pressure regulator because of some internal leak. note that i observed the leak while the engine was off. im not sure if the dribbling would occur with the engine running. although it seems like it would.
if only i had tested for this first i could have skipped everything above...although it was good i found those old orings on the injectors. all you need to do is disconnect the vac line from the regulator and look for fuel dribbling.
southern california, mid december 2011
about 190,000 miles
failed smog in every category except 25 mph NOX
besides failing smog, engine was hard to start hot and always smelled a little too gassy. never felt very peppy.
tested inlet and outlet temps of catalytic converter. outlet was significantly higher than inlet (indicating it works to some extent)
compression on all cylinders is 140 to 150 psi.
spark plugs look great with no fouling and they must have about 20k miles on them.
passed smog 2 years ago.
connected DRB II and ran engine test. returned with fault 1065 , which is O2 sensor running rich. the troubleshooting chart for that fault involves disconnecting the o2 sensor, and then monitoring the o2 sensor voltage while shorting various terminals on the harness. im not sure if i was doing this wrong, but my drb ii never showed anything but 0V (shorted or not) during this test, even when the actual pins on the harness measured 5V (not shorted).
i measured the voltage for the heater of the o2 sensor, and found it was 0V. This is because its only 12-14V for about A SECOND after you turn the key on. once i discovered this, i found the voltage to be about 12V for the o2 heater.
while running, the O2 sensor voltage (monitored via DRB 2) clearly swang between 1 and 4V like it should. it appeared to be working.
so now I began to believe the fault 1065 was real, and there was something causing the system to run rich at some point during the engine test, and the O2 sensor was probably working ok.
measured fuel rail pressure. 33psi at idle with vac hose, 40psi idle without vac hose. if engine is shut off, loses pressure at about 1 psi every 7 seconds.
removed fuel rail to observe injectors for leaking. noticed that tons of fuel would leak if i moved injectors around. it was leaking past the fuel rail orings. the intake manifold orings looked okay, but the fuel rail orings were hard as rocks. replaced all. now the leak was fixed, so i could actually observe the injectors outputs for leaks. none seen. suddenly i noticed that there was fuel dribbling out of the fuel pressure regulator vacuum line nipple.
so I'm assuming that was the whole problem. the intake manifold was sucking gobs of fuel through the fuel pressure regulator because of some internal leak. note that i observed the leak while the engine was off. im not sure if the dribbling would occur with the engine running. although it seems like it would.
if only i had tested for this first i could have skipped everything above...although it was good i found those old orings on the injectors. all you need to do is disconnect the vac line from the regulator and look for fuel dribbling.