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Frequently Asked Questions

Please check here first for answers to your questions.  We encourage you to Download the documents that may be applicable to your product.

If you don't find the answer you are looking for here, send us an e-mail with your inquiry info@dc-johnson.com.

Q:  My "Johnson Box" doesn't look exactly like the one in your pictures, (or it has a different name on it).  Did D.C. Johnson and Associates Inc. also make or license them under a different name?

A: NO:  There were a number of unauthorized counterfeits made though.  Some counterfeits had a circuit board that was an exact copy, some had the same circuit with a different layout (perhaps even a sub standard single sided PCB).    If the circuit design was significantly different, it is not technically a counterfeit.  While a number of competitive products to the original D.C. Johnson and Associates Inc. designs emerged, most were counterfeit copies and none were produced in comparable numbers.

NOTE:  Obviously, dc-johnson.com cannot provide detailed technical assistance for products that were not produced by D.C. Johnson and Associates Inc.  However, our technical documentation can serve as an effective reference, regardless of the origin of the equipment you may actually have.

Q: Someone recommended that I get rid of or disable the "Johnson Box".  I have heard it called "Junk" or have been told that they never actually worked.  What is the response of dc-johnson.com?

A: If you own a "Grey Market" vehicle that was "Federalized" (Certified to meet FEDERAL emissions regulations) with a "Johnson Box", and the unit is subsequently disabled or removed, it may not be legal to operate it on public roads depending on the laws of the State in which it is registered.  Selling such a vehicle can raise additional legal issues, possibly including Federal legal issues. Therefore, it is strongly recommended to maintain the emissions system and ensure it is fully functional.

As for concerns of quality or functionality, tens of thousands of genuine D.C. Johnson and Associates Inc. emissions control units were produced and installed. These installations were subject to 100% testing at Accredited Certification Laboratories in order to be granted Federal Certification (a more rigorous standard than any volume auto manufacturer must meet).  Many units are still operating after over 30 years in service.  This record speaks for itself. 

On some vehicles the emissions control system may have been subsequently disabled or damaged. There is no reason that a deficient or damaged installation cannot be restored to full function.

Q:  Doesn't this emissions control stuff hurt the performance?

A: When an emissions control system is properly designed and installed, performance will not be adversely affected.  Common mistakes include installing undersized catalysts, and failing to connect or properly adjust the switches for full throttle and low manifold vacuum (indicating heavy load).

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