Is it the oxygen sensor?

Needing a coroboration of opinions here...

200,000km/120,000Mi. on a 97 SL1 which has had amazingly little trouble.

But the "Service Engine Soon" light is now lit steadily and I haven't driven
it through a puddle and it's the same low grade gas I've been using for the
last few years.

The plugs were changed 15,000Km ago when it started to sputter going up
minor hills and PCV valve too was changed then. Wires are the same
Mangacore ones that I put in at 100,000Km ago.

Starts have been funny over the last few months in that it doesn't necearily
start on the first turn and I could hold the key there for a while and get
nothing, but if I let go and try it again, it starts immediately.

Also, if it did start after holding it for a while, the start is kinda rough
and sputtery.

From my RC airplane days, that was always a sign of too rich a mixture.
Hence I'm guessing O2 sensor.

Also, anyone know a rough estimate on cost for one of these things?

Cheers

 

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.

 

Hence I'm guessing O2 sensor.

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 ]