gas mass sensor for chevy silverado

[merlin1977]

does anyone have a wiring diagram or tech info or testing procedures for the gas mass sensor on a Factory Impco cng system on a 98 chevy silverado?

[clay]

Re: gas mass sensor for chevy silverado

I've tried to find out the same info now going on two weeks with no luck! I have talked to Impco, Quantum, GM and the Internet all with not luck. No one wants to admit that they have the schematics for these CNG components, but I know that all three have them because they have all participated in the design and manufacturing, and servicing of this equipment. I wish you luck and if you do find out anything please post it so we can all know.

Thanks again Clay

[mrpsycho1]

Re: gas mass sensor for chevy silverado

If you are in the Tulsa area, I would let you swap it out with mine. This would only serve to "shotgun" your system to determine if it is at fault or not. Those 97-98 Impco systems are rugged with the gas mass sensor being the weak link. The meter half is durable but the sensor is weak. Is it dying when it switches to NG or running rough? Any DTCs from the PCM? Anyway, I have one in stock if you want to try it, but due to the cost of the CNG parts, I would ensure all the GM parts are good first. O2 sensors (esp. fronts), MAP and MAF sensors, TPS and temp sensors. Even a knock sensor can cause too much retardation when running CNG. You might then direcly power the HPL and LPL to ensure they manipulate. If you have a pressure gauge between the HPL and LPR you are half done. It would be well worth paying a dealer or trusted mech to hook up to a computer. If you are in the Tulsa area, I can check these for you. Most GM dealerships have no idea what to do with NGVs. Ken