A Typically, the flashing "check engine/service engine soon" light points toward multiple misfires and a significant amount of excess unburned fuel reaching the catalytic converter -- enough to potentially damage the converter. With no fault codes stored, start with a back-pressure test of the exhaust system to determine if the converter may be clogged and/or the exhaust system restricted. This test involves removing the front oxygen sensor, installing a pressure gauge and running the engine. More than about 2 pounds per square inch (p.s.i.) back-pressure could indicate some type of restriction.
The intermittent nature of your misfire might also point to a possible ignition problem. Since you had new plugs and wires installed, the coil packs may be suspect. Also, my ALLDATA database pulled up a Nissan recall in 2003 that called for upgraded crankshaft and camshaft position sensors in certain Nissan engines from that year. It might be worth checking with the dealership to see if your vehicle was included and whether the updated parts have been installed.
Q A lot of water got in my '98 Jimmy's gas tank. I drained the tank and pumped out the water. It will run if I pour gas in the throttle body but quits when I stop pouring gas in. It will not stay running. Please help!
A Can you hear the fuel pump run for 2 seconds when you first turn the key to the "on" position before cranking the engine? If not, check its relay. Also, look for a green unconnected wire near the driver's side inner fender that is used to prime the fuel injection at the factory. It's possible to apply battery voltage to this wire -- make sure you identify the correct wire! -- to test-operate the fuel pump. And, finally, debris may be clogging the sock filter on the fuel pickup inside the tank.
Q It may be a bit late in the year to ask this, but I have a couple of cars that sit outside all winter and I cringe when heavy weather rolls in. Are there any car covers available that actually protect your car from hail damage?
A This is sort of a good news/bad news question. A car cover made of heavy fabric or plastic might protect from hail damage, but would potentially damage the finish from abrasion.
For decades I've parked cars outside and intentionally left them uncovered. Maybe I've just been lucky, but I've never had any damage from rain, snow or hail.
The "garage in a box" concept -- a light metal framework with a vinyl covering and zip-up "door" -- would protect the vehicle from hail and heavy storms. These are portable garages, so to speak, and typically sell at home improvement stores for less than $500. The heavier metal framed steel-roofed garages are somewhat more expensive but obviously more protective and durable and would be a better choice for more permanent outside storage.