Post by JLantz on Dec 14, 2004 21:35:42 GMT -5
My 91 4wd FI Justy is a daily driver of around 60 miles a day. I experience power loss while cruising on the freeway very rarely. Usually it lasts for a few seconds, I cuss under my breath, downshift, mash the accelerator a few times and it goes back to normal.
It didn't go away the last time that I drove.
Here are the symptoms and the diagnostics I have performed. I am stumped at this point and would be grateful for some third party advice.
Symptoms:
-Major power loss; Hills I would burn up in 5th at 4000rpm are now struggling in 4th at 4000rpm.
-Idle is rougher than normal and causes lots of vibration.
-More light grayish smoke out of the exhaust than is normal for my engine. Not white (coolant) or black (too rich). My engine has high oil consumption, so it always smokes a little bit. This is due to the rings; the head was rebuilt 9000 miles ago.
So this sounds like a cylinder isn't firing.
Diagnostics:
-Pulled the spark plug wires while engine is running; removing #2 produces no effect, removing #1 or #2 kills engine. I can here the spark when I hold the wire boot just off of the #2 plug, so the wires seem good (they're fairly new).
-Removed #2 plug and started the engine. Plug sparks when grounded.
-Cleaned terminals in the distributor cap and rotor. Seems to run smoother.
Maybe its not getting fuel:
-Listened for the injectors to fire with the stethoscope. #1 and #3 are loud and clear, but #2 seems faint. Could be placebo effect, though.
-Swapped #1 injector with #2 hoping to isolate bad injector. No result, so the injectors are fine (I had them serviced 10000miles ago).
-Checked for continuity between the ground wire of the injector wiring harness connector and the engine block. Good.
-Checked the voltage at positive wire of injector wiring harness connector with ignition on, engine not running. 14v.
-Checked voltage between positive and negative terminals of the injector wiring harness connector. My multimeter read the pulsing voltage, but due to my mistake in reading the scale I don’t have the exact value. I will retest this in the morning.
Mechanical?
-Removed the valve cover and rotated the engine through to check if a valve was sticking open. Nope.
-I could do a compression test on #2, but it seems unlikely that the rings would have totally failed. I know they’re worn, but not to the point of completely failing to produce power. Also, if the rings had failed, all the blow-by would come out the crankcase breather, which it isn’t.
Here are some ideas I ruled out because they would affect all cylinders:
-Clogged cats or muffler
-Clogged fuel pump
-Clogged intake
-Bad coil
-Slipped timing belt
WTF?
It didn't go away the last time that I drove.
Here are the symptoms and the diagnostics I have performed. I am stumped at this point and would be grateful for some third party advice.
Symptoms:
-Major power loss; Hills I would burn up in 5th at 4000rpm are now struggling in 4th at 4000rpm.
-Idle is rougher than normal and causes lots of vibration.
-More light grayish smoke out of the exhaust than is normal for my engine. Not white (coolant) or black (too rich). My engine has high oil consumption, so it always smokes a little bit. This is due to the rings; the head was rebuilt 9000 miles ago.
So this sounds like a cylinder isn't firing.
Diagnostics:
-Pulled the spark plug wires while engine is running; removing #2 produces no effect, removing #1 or #2 kills engine. I can here the spark when I hold the wire boot just off of the #2 plug, so the wires seem good (they're fairly new).
-Removed #2 plug and started the engine. Plug sparks when grounded.
-Cleaned terminals in the distributor cap and rotor. Seems to run smoother.
Maybe its not getting fuel:
-Listened for the injectors to fire with the stethoscope. #1 and #3 are loud and clear, but #2 seems faint. Could be placebo effect, though.
-Swapped #1 injector with #2 hoping to isolate bad injector. No result, so the injectors are fine (I had them serviced 10000miles ago).
-Checked for continuity between the ground wire of the injector wiring harness connector and the engine block. Good.
-Checked the voltage at positive wire of injector wiring harness connector with ignition on, engine not running. 14v.
-Checked voltage between positive and negative terminals of the injector wiring harness connector. My multimeter read the pulsing voltage, but due to my mistake in reading the scale I don’t have the exact value. I will retest this in the morning.
Mechanical?
-Removed the valve cover and rotated the engine through to check if a valve was sticking open. Nope.
-I could do a compression test on #2, but it seems unlikely that the rings would have totally failed. I know they’re worn, but not to the point of completely failing to produce power. Also, if the rings had failed, all the blow-by would come out the crankcase breather, which it isn’t.
Here are some ideas I ruled out because they would affect all cylinders:
-Clogged cats or muffler
-Clogged fuel pump
-Clogged intake
-Bad coil
-Slipped timing belt
WTF?