Fiat Marea Weekend 1.6 ELX '98 LPG 190.000 km

I'm trying to determine if my oxygen sensor is shot. The car sometimes starts to "stutter" at medium to high speed, I'm able to hold speed, but any acceleration is in vain, the engine starts to vibrate and refuses to cough up more power. Unless I crank the accelerator. Then all is well, and it gives you a nice "pat in the back". But then I'd be going 185 kph in the end, which is expensive to say the least

And lately it's been running real bad on petrol (An LPG car runs on petrol the first minute or so).

So am I right to assume the oxygen sensor is at fault, but is ignored at full throttle?

FYI, to ensure service temperature of the O2 sensor. the probe is equipped with electrical resistance supplied by the battery. The heater and probe resistance may be measured by disconnecting the connector and connecting an ohmmeter: (4 wire sensor)

Heater resistance = 4.3 to 4.7 ohm
Probe resistance = 5K ohm
Operation of the 02 sensor should be checked at 45,000 and 90,000km .

subija

If you car runs on lpg make sure theres not a fault on that first, possibly trying to run on both

Originally posted by FiatExpert
If you car runs on lpg make sure theres not a fault on that first, possibly trying to run on both

Click to expand...

Hmm, I don't believe that's the case. The car runs perfectly on lpg, and the switchover is as it's ever been. Injector cleaner did some good, but I'm not sure on its behaviour at high speed. It glitches very briefly - as brief as a piston misfire - irregularly, once every few minutes or so. It's been doing this for more than 6 months.

Could there be a damaged wire of the heater part of the O2 sensor?

And do you happen to know why the engine runs fine at full throttle, and which sensors are ignored?

Regards,
Joris.

At full throttle the idle control valve is effectively "off" (throttle fully open). That is a sort of sensor unit.

Maybe that helps?

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<font color="maroon">'98 Marea Weekend ELX (1.8 16v).</font id="maroon"></font id="Verdana">

and it runs fine on lpg?
sounds like one of the fuel injectors is on the way out or allready dead, most common running fault on a 1.6.
if you want too test them they should all be about 14 ohm ish, a faulty one will be alot less.

Originally posted by kebab
and it runs fine on lpg?
sounds like one of the fuel injectors is on the way out or allready dead, most common running fault on a 1.6.
if you want too test them they should all be about 14 ohm ish, a faulty one will be alot less.

Click to expand...

Well I'll say this: last summer on vacation in Norway it intermittently started to show the problem. We drove about 2/3 of the total distance of 5000 km on petrol and the rest on gas. But it has shown the problem on gas, just much less frequently.

I added injector cleaner, which solved the idle problem, and this week the sensor was tested (obligatory car check, dunno what it's called in UK) and approved, but they had to drive the car for 1/2 hour to get to pass.

So I have my answer. The sensor is OK.

Thanks to everyone who offered help.