Is it the oxygen sensor?

Get the code read. Low grade as in octane? Makes no diff, 87 octane is all you need for your engines compression ratio.

If you dont check your wires with an OHM Meter then you never know what you got. Look your plugs over again as well.

Check out fuel pressure. Whens the last time you changed your fuel filter? The fuel pump runs for 2 seconds after the key is turned to run. You might be waiting for fuel pressure to make it past your fuel filter.

25,000 miles Should be everyones limit on fuel filters. If you starve electric fuel pumps of fuel or restrict the flow of fuel you will no doubt damage electric fuel pumps.

O2 sensors dont usually go bad on their own but a bad running engine will take them out.

Fuel filter 15 bucks US. Fuel Pump 200-400 bucks US. Filling up before your tank goes below 1 quarter, Priceless.

The O2 sensor has no impact on the start-up. In fact, the computer doesn't even use its output until the engine is warmed up. The start problems sounds more like a fuel pressure problem. When you turn the key, the fuel pump only runs for a very breif period unless the engine starts. If the pump is weak, or the the system isn't holding pressure when the engine is turned off, then there might not be sufficient fuel available to start the engine during the breif period of fuel pump operation during the start sequence. Going through the starrt sequence a second (or third or fourth) time gives you another shot of fuel. Since you got one shot of fuel from the first start attempt, the second (or further) attempts can provide enough fuel to start the car. Another fuel system problem that can cause start problems is a leaky injector. These can hurt in two ways -1), a leaky injector(s) allow the fuel system pressure to bleed off, causing the problem discussed above, usually after a long period of the car setting, and 2) they can casue one cylinder to be flooded out - usually after a shorther period of setting and followed with a black cloud of smoke when the car actually starts.

I suggest that you need to have your fuel pressure checked. If the pump is going bad, you can have insufficient pressure, leading to hard starting, and a lean mixture.

Regards,

Ed White

It's either a fuel pronblem (see other p;osts), or maybe a flakey ignition module (I've had this on other cars). It's NOT the O2 sensor. The O2 sensor doesn't do anything until the car's warmed up, the computer's decided it's waited long enough, the signal's in range, and your foot's on the gas.

Don't guess. Spring for a diagnostic from the dealer and it will pay for itself if it prevents you from buying one part you don't need.

Lane [ l a n e @ p a i r . c o m ]