Impco System Update....Post updated 12/20/13

I bought this truck in September.  I noticed that as the temperature dropped over the next two months, I would sometimes have trouble when operating in CNG mode.  The engine would sometimes miss.  Sometimes it was barely noticeable, and sometimes it was so severe that it I had to switch it over to gasoline.  Once on gasoline, it ran fine.  I contacted Impco Technologies and after some discussion with their automotive technical support department as well as emailing photos of engine components it was ascertained that there is an update to the CNG system on this truck that had not yet been done.




There are fuel rails on the Impco system.  Systems installed prior to 2012 had an issue with cold weather and Ford injectors.  I cannot find any reports of this problem with other makes of vehicles.  As the temperature drops, it creates a problem delivering CNG to the engine.  The solution to the problem is to install fuel rails with heaters along with some other items and a re-calibration of the system.  This update corrects the issue that I was experiencing.  I ran into a problem initially with Impco because the period of time for them to cover the update at no charge had expired, and the retail cost would have been around $1,600.  After explaining my situation to their customer service representative, she was willing to appeal the denial of warranty to the management at Impco and they ended up covering it at no charge to me.  Chevyland in Shreveport is the only approved Impco service center at this time.  I was able to get the vehicle into their service department and have the update installed without any further issues.  The CNG technician at Chevyland had prior experience with this update. Jimmy Granger Ford was again kind enough to provide a vehicle for me to drive while this update was installed.  It ended up not costing a dime, which I am very thankful for, but again it was a hassle that I would not have experienced had I simply just bought a gasoline powered vehicle.

Below is a photo of the updated fuel rail which is attached above and to the front of the engine.  This photo was taken from the passenger side of the engine compartment.

Below is a photo of the underhood components of the IMPCO system since the update.

I do not know the specifics of exactly what was done in the process of updating the Impco System, but I notice a few differences as I drive.  In an earlier post I discussed the fact that the vehicle operates on gasoline until the system switches over to CNG.  The Impco system makes this decision when certain vehicle parameters are met.  It switches to CNG much quicker when the vehicle is already warm, but first thing in the morning, it takes some time to heat up.  Prior to the update, this usually happened about one mile from my home.  Since the update, it switches over after about 1.5 miles.

Prior to the update, I noticed a very brief engine miss anytime the vehicle switched to CNG from gasoline.  It never created an issue or caused me to become alarmed, but it was still there.  Since the update I cannot detect when it switches to CNG when the vehicle is warm.  There is a slight miss sometimes when it first switches in the morning, but once it is warmed up I don't notice at all.

I also notice that the vehicles estimation of miles per gallon is more realistic that it previously reported when operating on CNG.  When I first drove this truck it indicated that I was getting around 20 mpg on CNG.  I didn't see that as anywhere near realistic since CNG cannot be more efficient than gasoline.  As it the temperature has cooled, it has dropped to around 12, sometimes 10.  Again, not realistic but MPG is not relevant when talking about CNG efficiency which is expressed in dollars per mile so I ended up really not caring about the MPG discrepancy.  I will compare this information with the data collected as I travel and update you on the accuracy of the current display.

There was also another benefit of getting the update.  In 2010 Impco attempted to have the vehicle's gasoline gauge synchronize with the CNG system and display the amount of CNG left in the tank.  The idea was that you would be able to know how much CNG and gasoline were on board simply by pressing the BRC button.  The problem was that for reasons unknown to me, this wasn't an instantaneous change of the needle.  The needle moved agonizingly slow, so slow that it never reflected the accurate amount of gasoline on board before the Impco system switched over to CNG.  In order to know the amount of gasoline on board, you would have to run the vehicle on gasoline for a greater period of time.  To me this would be a waste of money, because the idea is to run CNG as much as possible.  While operating on CNG, the gasoline gauge would fall very quickly to between 1/2 and 1/4th full.  Then it would slowly move to empty, once it got close to empty it would sound an alarm, even though the CNG wasn't actually nearing empty.  My lack of knowledge on this issue combined with my ability to see a catastrophe around every corner nearly led me to pass on buying this vehicle because I didn't want to experience this issue a couple of times per week.  I did resolve my questions by filling up with CNG and driving the vehicle continuously for 240 miles to discover that the vehicle gauge signaled empty within about 10 miles of the Impco system switching over to gasoline from CNG because the pressure was too low.  In the end Impco abandoned this effort at gauge synchronization on subsequent CNG  conversion systems so if you are considering an Impco system you won't have to worry about this issue.  I had accepted this as annoying but ultimately not relevant and was prepared to just keep on driving.  Happily, the update corrected this issue and now the gasoline gauge reflects gasoline only, and the smiley face gauge represents CNG only...no more annoying "dings"!

I am impressed with the performance of the vehicle since the update.  It seems to run smoother at lower RPMs and maybe has a little more power.  I will update this entry if I am able to capture data which reflects a change in efficiency or make other observations.

12/20/13

After the update was installed, I noticed sometimes while the vehicle was stationary that I could smell natural gas.  This wasn't constant, but it did lead me to return the vehicle to Chevyland for service.  They were able to correct the problem with no charge.  This was my second experience with the CNG section of the Chevyland service department.  Jeremy is their certified CNG tech, and a really nice guy to visit with.  I was able to glean that they are busy enough that Chevyland has hired someone to assist him in keeping up with the CNG related work.

In this example we have two local guys who are able to go to work everyday and earn a living.  They pay taxes and then spend those earnings maintaining their lives locally.  Those earnings were generated from a resource that is produced locally. In this region we have an amazing possibility....but it will be very difficult to make real.