Customer Experiences

Dennis LaGrua - Decarbonizing Kit Tester

I own several Fieros including an 85GT with 97K miles. Last month I noticed that performance had been a bit sluggish so I decided a major tune up was in order. The engine was running way rich due to a defective 02 sensor and a tuneup was also needed. After doing the major tune up and replacing the sensor, a significant performance improvement was noticed but it still seemed like the engine was not operating at full potential. After checking and rechecking all adjustments, cylinder leakdown, hoses etc. nothing unusual turned up. Since the engine had some miles on it and it ran rich for a while, I theorized that carbon buildup in the intake system, combustion chambers and dirt in the injectors may be the problem. A neighbor of mine who is a tool, die and mold maker has access to a $3000 fiber optic camera and often inspected his engines with it. When I told him of my theory he suggested that we do some checks. He volunteered to help me with an engine inspection and suggested that we start by looking inside the cylinders and see how they looked.

We removed three spark plugs,inserted the probe and looked around in each cylinder.... they were filthy - black piston tops, thick carbon deposits on the head and deposits on the valves. I guess this is par for an engine this old as oil seals begin to harden and seep, rings begin to wear a bit, sensors age and carbon from EGR function begins to accumulate. Before spending a day taking the heads and intake apart to clean everything, I decided to try a quick and easy decarbonizing. There are many chemical decarbonizers that you can buy at local auto parts places but I have not had good luck with them nor with the water method some owners have endorsed. On Ed Parks recommendation, I purchased a three component decarbonizing kit made for professional applications that he carries. One chemical is used to clean the injectors, the other cleans the throttle body and plenum and the third cleans the combustion chamber. Ed swears by this stuff and one guy in my club already used this kit with excellent results.

Following the instructions and the recommended procedure, last Tuesday we applied the chemicals. We since drove the car about 170 miles. The results of the decarbonizing was a much smoother running engine with improved throttle response and restored power. The decarbonizing kit apparently worked well but I wanted to know to what extent. We removed several plugs and a call to my neighbor with the inspection camera again brought the necessary equipment. We inspected several cylinders and noticed that the carbon was gone entirely. The cylinders were now perfectly clean. Ed Parks has apparently found the right stuff to clean Fiero engines internally and the results certainly proved that he knows what he is talking about.

From having used it and having tested it scientifically I can truthfully say that the decarbonizing kit sold by the Fiero Factory works like no other that I've used. Be advised that this 3 can kit is priced a bit higher that the average bottle of "cure-it-all" additives sold at the local auto parts stores but the best always costs more. It's available through Ed Parks at the Fiero Factory at

In short, this stuff works. * * * * *.

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