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[steven morrison]

Hi,
  OK I have a 98 zj with lpg conversion and 95,000 on the clock, OBD fault codes 0132 - 0138. (new TPS, plugs and battery) If I disconnect the 02 sensor it runs fine on petrol but not at all on LPG. So do I need a new sensor? Are universal ones any good? Do I have to buy a mopar one, thinking of the expense? lastly where can I purchase one from?

    Is this a jeep thing?
Dodgy sensor disconnect, runs without it.
Dodgy transfer case, remove and discard front prop, it'll run without it
Horrible incoherent nagging noises coming from the passenger seat, remove and discard?

   Any help appreciated
     Steve

[Jonny Jeep]

When on petrol disconnecting the upstream sensor forces the Jeep computer (PCM) to use it's programmed fuel tables. If the sensor is bad the engine can run rough with the sensor connected and will run fine with it disconnected. The downstream sensor is there to monitor cat performance.

I'm not sure how LPG systems use the O2 sensor info and what other sensors, if any, are monitored to control LPG operation. If the O2 sensor output  is required by the LPG system it makes sense that it wouldn't work without it.

As far as replacement is concerned, NTK are OEM supplier. You can get them via rockauto.com, or the UK site http://www.rockauto.co.uk on the UK site you can click include VAT in prices and in the basket you will see the shipped cost. Last O2 sensor I got from them was around £50. I think somebody bought one recently from lighthouse and said it was £70. Not sure what brand that was though. If you google rockauto discount you'll find a 5% off code easily enough too.

Regards the noise from the passenger seat, have you considered leaving it at home, rather than discarding completely? Perhaps chained to the kitchen sink so it doesn't go missing?

[Bandit]

Single point lpg systems that are ecu controlled do require the o2 sensor as this is what it uses to adjust the stepper motor valve, if its multipoint then the system uses the injection pulses and the o2 sensor input is purely for medicinal purposes only as in diagnostics, it seems that you probably have a single point system.

As im totally bunged up with a head cold, again, I havent looked up the codes, what are they for ??

[Jonny Jeep]

The codes are for both O2 sensors being high voltage.

[Bandit]

Any exhaust leaks around the manifold or down pipe area ??

The jeep ecu as previously said will default to basic if a fault is detected however the lpg system wont, if thats not working efficiently its possible the o2 sensors have maxed out for more than a few seconds which could throw a fault code in the jeep ecu, it may not be an o2 sensor at fault but just look like it, you could try a system reset and run on petrol alone just to see if it still shows a code or perform an o2 diagnostic with a volt meter to see what the o2 sensors are doing.

[steven morrison]

Hi
 Thanks all for the advice, working fine with disconnected o2 sensor on petrol, so new one ordered and on its way from Rockautos (express delivery for a NTK a tad over £50 not bad)
1/ No leaks around the manifold/exhaust.
2/  I'm a LPG noobie but the system is Sequential Gas Injection. Does that mean multipoint?
3/ Both codes point to o2 sensors, but what do you mean "being high voltage" (sorry not just a noobie bit of a thicko too!)
4/ Thanks for the Rockauto 5% code
5/ Thanks
 Let you know how I get on with the new 02 when I get it.

Steve

[Bandit]

Yes sequential is a multipoint, looking at the engine you should see an array of 6 lpg injectors with small rubber feed pipes going to 6 individual nozzles drilled into the inlet manifold somewhere near the face of the head, a single point has one big mixer ring that fits on top of the throttle body, the multipoint gets its timed injection from the petrol injectors and its ecu will add extra firing times to compensate for the extra lpg fuel needed to equal that of petrol, your o2 sensor will almost certainly be a 0-1v sensor 0v very lean and 1v being very rich, the petrol ecu will read that sensor along with others to finely tune the fuel delivery, if it fails then the ecu will default to preset so the multipoint may not function correctly, the o2 maybe connected to the lpg system and it set to use it other than diagnostic.

One thing to remember is lpg will seriously highlight any problems within the ignition system which are well hidden whilst running on petrol, so keep the ignition side up to scratch and you should be fine on lpg.