Gas Mass Sensor - Service

[kgibson]

I am looking to purchase my first cng vehicle and found a cavalier that says the cng does not work right and they THINK it is the gas mass sensor?

So two questions spawn from that 1.Any ideas how much it would cost to replace the gas mass sensor in an 01 cavalier? 2. Where in Utah do you go to get service on these vehicles in case it is not the gas mass sensor and for future cng issues if they arise?


Thanks,
kg.

[Highmarker]

Re: Gas Mass Sensor - Service

Is this the Cavalier in Ogden that is on KSL?

If it is the Gas Mass Sensor, they are available at Young Chevrolet in Layton. They run about $1800. The Gas Mass Sensor is the black box on top of the motor to the right of the circular piece (low pressure regulator). Rick Oliver at Sno-Motion in Salt Lake City is an authorized CNG conversion specialist.

You might want to check with Young Chevrolet on who they would recommend on fixing it. If you do end up getting this vehicle, make sure you get the old high pressure regulator that was replaced. I'm not sure if they replaced the high pressure regulator thinking that was the problem or not.

[kgibson]

Re: Gas Mass Sensor - Service

Thanks for the response I wondered if just any old chevy dealer would be able to service these for me? 1800 bucks is pretty steep and that is just a guess on what it might be.

yes it is.. I think with the right info I could lowball him and explain my reasoning.

I have been watching others in the area and just trying to make up my mind on what I want to purchase.

I have had a few cavaliers as rental cars (i travel a lot) and I have never been impressed but I am just looking for a commuter back and forth to SLC so it might be just the thing.

What do you drive? any recommendations that aren't a 20,000 dollar civic..

[Highmarker]

Re: Gas Mass Sensor - Service

kgibson,

I drive a 2001 Cavalier with 70k miles on it. I love it to death. I would stay away from the Ford Contours. I've heard they are problematic. I'm sure you'll find somebody that says that the Contours are nice cars, but they have their share of problems. Oddly enough, most of the problems with the Contours are not CNG related. Engine mounts breaking, transmissions going out, that sort of stuff. The main problem with the Cavaliers are the low pressure regulator and the gas mass sensor. You may want to do shopping around, I bet you can find the gas mass sensor cheaper online. I'm not sure if the gas mass sensor was made by Impco or not. You may want to check out www.impco.ws and see if you can find it.

As far as commuter CNG cars, the cavalier, the contour, and the GX are your only selections. Unless, you want to buy a Ford F150, or a Chevy truck/SUV that has been converted.

[Highmarker]

Re: Gas Mass Sensor - Service

I live in Roy, if you'd like to come look at my car.

[kgibson]

Re: Gas Mass Sensor - Service

cool thanks again I think I have narrowed it down to 3.

First choice being a cavalier
Second maybe a crown vic
third an f150

I will keep my eye out.

Kevin

[kgibson]

Re: Gas Mass Sensor - Service

Thanks I live in bountiful so I might take you up on that.

What more can you tell me about your cavalier?
What size tanks do they have in them?
What range do you get?
How long does it take to fill?
Anything else that a total noob might find interesting?

Thanks,
kg.

[Highmarker]

Re: Gas Mass Sensor - Service

kg,

Okay here we go:

Chevy made the CNG option on the Cavalier from 1998 to 2004. 1998-1999 models have a 3 speed transmission. 2000 and up have a 4 speed transmission. 2003-2004 models actually "drain" the CNG tank to a lower pressure than earlier models before switching over to gasoline. For example, my 2001 will go down to about 400 psi before it kicks over to gasoline, but my wife's grandmother's 2003 will go down to about 250 psi before it kicks over. 2003-2004 models have a little bit more power under the hood as well. All Cavalier have the same size of tank - about 6 GGE tank. In the winter you can sometimes get 6 GGE on a fillup while in the summer you are lucky to get 5 GGE, due to the temperature. It takes about the same amount of time to fillup with CNG as it does to fillup with gasoline - this is of course with a fast-fill. Slow fills (out of you house) usually take all night. I range from 130-140 miles per fillup. However, with a 2003 or 2004 you can get 150-160 miles.

Any other questions?

[kgibson]

Re: Gas Mass Sensor - Service

very informative.

THANK YOU!

[tallan]

Re: Gas Mass Sensor - Service

I drive a 2001 Cavalier with 122k miles on it. It's been a great car. I agree that the main problem with the Cavaliers are the low pressure regulator and the gas mass sensor. I have rebuilt the low pressure regulator on mine with no problem. I have also tried to find the gas mass sensor cheaper online with no success.

My friend purchased the Cavalier in Ogden that was on KSL and the problem is the GMS/MCV Assembly. Snow-Motion replaced the high pressure regulator thinking that was the problem, they had no idea. Snow-Motion said it was the GMS, after charging the costumer $1100. Then they wanted the customer to spend over $2000 to try something else. Does Snow-Motion really know what they are doing? This is not the first time I have heard problems with them. It's not hard to check and see if the HPR is working or not. Snow-Motions should have put the old HPR back and not charge the $1100.

The gas mass sensor was made by Impco but the division that built it is no longer part of IMPCO, they are Quantum Technologies. there tech number is 1-800-816-8691.

I took apart the GMS and found the problem, it took me about 2 hours to find and repair the PC board, now the GMS is in my Cavalier for testing and my GMS is in his car and running fine, so far his is running fine in my car. The Cavalier is a great running car and the IMPCO system is not a hard system to maintain or fix.

[Highmarker]

Re: Gas Mass Sensor - Service

tallan,

You seem to be very knowledgable on the Cavalier CNG parts. I have a buddy who has a '99 Cavalier that stalls out on him while driving. He thinks its the GMS. I told him about the '02 Cavalier in a recent thread that is having the same problem and the owner thinks its the LPR. What are your thoughts? If it is the GMS, maybe we could hook and up and repair it. Let me know. Thanks.

[cngbuck]

Re: Gas Mass Sensor - Service

In most cases the GMS can be diagnosed at a GM dealer that is familiar with CNG. They have all the proper diagnostic equipment for the GM/Impco system.