Bear with me because this is a tough one to explain without being able to show. Recently I've had a problem with the tii where it kind of sounds/feels like its running on 3 cylinders, even though most of the power is still there. I checked the wires and they all worked so I thought it may be worn plugs, well I just changed those and they didn't really fix anything. The car runs smooth at idle and the problem only occurs under load, it kind of sounds like the Boxer engines in the WRX's or STI's if any of you are familiar with Subarus. It still cruises fine in the freeway though you can hear the problem but not feel it which is probably because I'm just cruising. The car will backfire from the exhaust occasionally at idle and under acceleration, during one of its backfiring sprees (at idle) I decided to pull the plug wires again (don't ask why) and found out that the backfiring would stop when I pulled the #4 plug. Now I'm new at this stuff so that's why I'm turning to you guys. I'm also thinking fuel injector pump maybe, but I wouldn't take anything I say too seriously. Anyway hope you guys can help, thanks.
I'm leaning toward injector pump not delivering enough fuel. Can you tell if the plug is fouled or too lean?
Have you checked the distributor cap? If you're a true 2002-er you must have a spare in the car Clean it with solvent and decarbon it with some gentle emery cloth until nice and shiny (and the rotor too)
The only time I've had back-firing in 29 years of '02ing was due to a loose spade connector on the wire to the condenser on my '70. You can't imagine what we went through to find that!
Make sure the valve stem/cam clearance is at least .01...damn... forget what I used to tune mine to.. a little more clearance for the exhaust valves... remove the valve/cam cover & use a long wrench connecting to the nut on the front crank pulley to turn over the engine and check the clearance at the low side of the cam lobe - you could have an exhaust valve hanging open, or a burnt valve )~: sometimes a spark plug will go bad, or the porcelain may crack - I used to keep a couple of good but used plugs around in case a newer plug went bad; make sure your head is torqued down to spec (you will need a torque wrench for that), you may have a head gasket leaking (in that case the hot gases of the cylinders 'talking to each other' can erode a channel in the head...); get a compression tester, to check the pressure, you'll need a remote starter switch - run the engine to operating temp', connect the remote starter switch from the battery + to the power connection on the starter motor, remove all spark plugs and while turning the motor over with the remote starter switch (of course withthe ignition off) stick the compression tester into the spark plug hole of each of the cylinders (you have to be sure to release the pressure via the tire type valve in the head of the compression tester) - all cylinders should read about the same - any that are low have a compression problem, which can be 1) a valve hanging open, 2) a burnt or bad valve 3) a head gasket leak --- check the spark plugs first, second, but part or routine maintenance, make sure you have the same (or very close, more for exhaust valves) valve stem/cam clearance on all valves and if all checks out.. then test compression and let me know how things turn out... (I had a '74 tii.. ran it up to 240k... damn smart little machine...)
... yah and of course like someone already mentioned, the distributor cap... that can do it, a hairline crack and winter road salt or some road salt alone (make sure the rubber seals are clean and firmly on... ) can draw away some current - like I said about keeping spare plugs, I would keep almost spare everything because it assists greatly in diagnosing problems.... wires, pvc valves, rotor, condenser... keep a box of spare everything that is routinely replaced... and carry spare belts...
I had something similar happen to me once - weirdly enough one of the sparks finally blew itself out of the engine. No crossthreading or anything and yet it felt like it was in there - not loose at all. just to suggest something ridiculously simple.
