Jeep cherokee 2004
Hi All...I have a 2004 Jeep Cherokee with lpg conversion...This vehicle has to be started on petrol then switched over to gas once driven a mile or two...The problem is..is it's really struggling to start using petrol lately and can take up to 15mins to start up...diagnostics show co2 sensor defective...I dont believe this because if it was the sensor would it just not start?...once it starts (eventually) I switch to gas and it runs beautifully...any Ideas...as I suspect its more likely be the petrol fuel pump

 

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JeepKJ, jeepforum and lostjeeps have forums specifically for the Liberty/KJ, if thats what you have. If you have a Grand Cherokee, youre in the right place.

 

Yes Grand Cherokee..thanks...Ps...I'm in the Uk (England)

 

if the sensor is sending high levels of co readings to the PCM(powertrain control module) it will not start. PCM will shut down the injectors, unplug the sensor it will default to a lower number, the PCM will respond by going into limp mode and the vehicle should start, also...is this a liquid injection propane setup or evaporator system?

 

Thaks so much for reply "doc"...it's liquid injection propane...What confuses me is, as you say.. If sensor issue.. the PCM will shut down the injectors... Surely that means the engine wont start at all..but it does start eventually and once I swich to LPG it all works fine

 

there are two co sensors if I remember correctly, unplug the upstream sensor, and see if the bloody thing pops to life faster...........also have you run any additives to the petrol tank to keep the injectors free of gummy deposits caused by the propane?

 

the reason this system requires the petrol to start it is because the cylinders need to be at a certain temperature in order to achieve a clean burn from the propane, much like diesel but without the need for higher compression ratios

 

Again..thanks so much for help..I will give your suggestions a try...and let you know how it goes.