Hello, I just purchased an old (1994) GMC pickup that was apparently converted to run 'Dual-Fuel' . It has a CNG tank in the bed and a plaque on the dashboard that proclaims its clean burn ability. It also has a button that reads "push to read fuel level". This was a Michigan Department of Transportation vehicle. Although I don't plan to run it on CNG because of the lack of availability in my area, I would like to find out as much as I can about the conversion. There seems to be an excessive amount of spark knock running on regular gasoline. There is a part under the hood labeled EDO and another with ANGI. There is a module on the firewall called "GM timing optimizer" but google searches turn up precious little. Can anyone help Identify?
Thanks
Thanks
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