Cavalier Runs bad on CNG

[Tom Johnson]

I filled the CNG tank the other day and the car runs terrible now. Ran fine before filling. It backfires and misses, seems to run better at higher RPM. Runs great on gasoline. Can you buy bad natural gas?

[CH-4]

Re: Cavalier Runs bad on CNG

Yes. It sounds like water in your system. Contact your nearest cng service center to have the system flushed; hopefully there's no damage to the components.

[freedml]

Re: Cavalier Runs bad on CNG

It's possible. Did you pull the fuse to make it run on gasoline to compare?

[Tom Johnson]

Re: Cavalier Runs bad on CNG

I had trouble starting the car after it had stalled. It started on gasoline and ran fine. Only has trouble running on CNG.

[kirkbenge]

Re: Cavalier Runs bad on CNG

Start with you plugs and wires. CNG is much more sensitive to bad plugs/wires than is gasoline. You may not notice any problems on gasoline, but on CNG, a single slightly burned plug will cause rough idle and backfires.

[larrycng]

Re: Cavalier Runs bad on CNG

You might want the composition of the fuel from the supplier; get an inferred mass gas spectrometer breakdown, I should have a minimum of 88% methane. Watch out for levels of N2 and CO2 above 1% and with other gases. Either that or a "load of oil" in the CNG

I can dream can't I

Larrycng

[CH-4]

Re: Cavalier Runs bad on CNG

Start with you plugs and wires. CNG is much more sensitive to bad plugs/wires than is gasoline. You may not notice any problems on gasoline, but on CNG, a single slightly burned plug will cause rough idle and backfires.

Stop already with the plug wires, if it runs on gasoline then its the alternate fuel not the ignition.

[Highmarker]

Re: Cavalier Runs bad on CNG

Tom,

I notice that you are in Utah. Which station did you fill up at? I believe that Questar does not use dryers during compression. It could be possible that your filter(s) are plugged. You may want to look into that.

[Tom Johnson]

Re: Cavalier Runs bad on CNG

Thank's I'm in Cedar City only one station here. i have takled to others who also run CNG they have had no problem. Seems to eliminate the bad gas theroy. I will check the filters and replace the plugs and wires. Thanks for the help

[siai47]

Re: Cavalier Runs bad on CNG

What year is your Cavalier? Pre 2003 models only have a small filter in the HPR, later models have a paper style element also. If it was a plugged filter, it would most likely run OK at idle and low speeds and start having problems as more load is applied to the engine---opposite of what you are seeing.

[Tom Johnson]

Re: Cavalier Runs bad on CNG

Hey I changed the spark plugs and the car runs great. There must be a big difference in the way gasoline burns compared to CNG. It ran fine on gasoline but would barely run on GNG, but now it runs great on both. Thanks so much for the help.

Happy Camper
Tom

[catfish]

Re: Cavalier Runs bad on CNG

Ok I have a 2001 Cavalier that seems to have issues starting in heat sometimes. Or if it does not start the first time I turn it over, I have to try again and it takes around 5 seconds to start. Does this seem common, also is this hard on the starter or am I being over concerned?

Plus someone had mentioned something about filters for this year, do they need to be changed often, where can i find them, and how much do they cost?

I have had this car since 2005 and just wondering if the issues are just beginning to start?